2006, Jeri Thesis

SPATIAL ECOLOGY OF HATCHLING AND JUVENILE KOMODO DRAGONS (Varanus komodoensis) IN THE KOMODO NATIONAL PARK, INDONESIA

MUHAMAD JERI IMANSYAH

THESIS SUBMITTED IN PARTIAL FULFILMENT FOR THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

FACULTY OF SCIENCE AND TECHNOLOGY UNIVERSITI KEBANGSAAN MALAYSIA BANGI 2006

EKOLOGI SPATIAL TETASAN DAN ANAKAN BIAWAK KOMODO (Varanus komodoensis) DI TAMAN NEGARA KOMODO, INDONESIA

MUHAMAD JERI IMANSYAH

TESIS YANG DIKEMUKAKAN UNTUK MEMENUHI SEBAHAGIAN DARIPADA SYARAT MEMPEROLEH IJAZAH SARJANA SAINS

FAKULTI SAINS DAN TEKNOLOGI UNIVERSITI KEBANGSAAN MALAYSIA BANGI 2006

iii

DECLARATION

I hereby declare that the work in this thesis is my own except for quotations and summaries, which have been duly acknowledged

5 December 2006

MUHAMAD JERI IMANSYAH P28345

iv ACKNOWLEDGEMENTS I am grateful upon The Almighty and Merciful Allah S.W.T and his Prophet Muhammad S.A.W that by His will has bestowed me a good opportunity to explore one of the tinniest parts of nature’s secret. This thesis has benefited from the help of many people during all the stages of its maturation. Coming at the end of this work, I wish to list here all the contributions that made this work possible, by order of apparition; Special thanks to Prof. Dr. Zubaid Akbar Mukhtar Ahmad for thesis supervision and every scientific discussion. I particularly thank Dr. Tim Jessop, my co-supervisor his assistance in providing research funds and equipments, more over in directing my field research and scientific writing progress during it. Without their help, this work had probably not successfully merged. Special appreciations should be awarded to my fellow Research Officers at CRES Komodo Project; Deni Purwandana, Achmad Ariefiandy, and Ibrahim, for their great friendship, assistances and vigorous work in the field catching the dragons, and also developing data base for my scientific analysis. I would like also to appreciate my research assistants; Dimas, Aris, Niken for the hard work in the field tracking the dragons. I should be indebted Dr Claudio Ciofi (University of Florence, Itali) for his assistance in writing research-grant proposal for fundraising, and his scientific advices in data analysis and thesis writing. Particular thank to Dr. Joana Sumner (Australian National University, Australia) and Dr. Shukor Md. (Universiti Kebangsaan Malaysia, Malaysia) for their assistance in reviewing this thesis. Avery special thanks also should be given to my parents: Abdul Azid Muchtar and Aas Sadiah; and my younger brothers and sister: Oris Junisa, Atus Satriawan, Widia Putri Julika. Last, but not least, a special grateful and dedication should be awarded to the most amazing woman in my life, my beloved wife, Eva Fairus Balahmar. Their patience, passionate, and encouragements to kept lifting up my performance and through the hard time during the research and scientific writing. This work will not be done very well without their support. It is also should be acknowledged that this study is part of a long-term conservation and research project undertaken by CRES with the Komodo National Park (KNP). I would like to thank the KNP management for granting permission to work across Komodo National Park, providing field staff and accommodation. This study was funded by the Zoological Society of San Diego (ZSSD), the American Aquarium and Zoo Association (AAZA), the Komodo Species Survival Plan (Komodo SSP), and the Oriental Bird Club (OBC). Permission for this study was achieved from the Komodo National Park management. Administration assistance was provided by The Nature Conservancy (TNC) Bali Office through a MoU between TNC and ZSSD.

v ABSTRACT Radio-telemetry and mark-recapture techniques were used to investigate and compare patterns in the spatial ecology of hatchling and juvenile Komodo dragons (Varanus komodoensis) in the Komodo National Park (KNP), Indonesia. Radio-tracking was conducted in Loh Liang, Komodo Island, between March-July 2004 and 2005, while the mark-recapture study was conducted in 10 major coastal-deciduous-forests across four islands in KNP from 2003 to 2005. Estimated average daily distance moved by hatchlings was (32.62 ± 12.67 m/day) compared to juveniles (129.14 ± 41.71 m/day; t-test t1,9=-3.01, p=0.02). Minimum Convex Polygon analysis showed that hatchlings used significantly smaller activity areas as compared to juveniles, (3.02 ± 0.73 ha and 24.31 ± 8.38 ha; t-test; t1,9 = -3.66, p = 0.01). In five of six activity areas, the activity areas of juveniles overlapped with one (n = 4) or two (n = 1) conspecifics with the extent of overlap ranging from 4.84 – 91.01 %. With respect to habitat use hatchlings were almost entirely arboreal (97.70%) compared to juveniles which more terrestrial (71.0%) (Chi square test; x2 = 239.22, p ≤ 0.01). With respect to elevation there was a significant preference for hatchlings to be located in the lowest elevation class (< 25 m) as compared to juveniles dragons (25 – 50 m) (Chi square test; x2 = 25.127, p ≤ 0.01). There was a tendency for hatchlings to occupy Tamarindus indica trees (45.37 %) as shelter whilst juveniles predominantly used crevices under or among rocks (51.77% ± 5.72). There was also a significant correlation between long distance movement and area size of the valleys (Pearson correlation test; r = -0.125, p ≤ 0.01) and the degree of the slope (Spearman correlation test; r = -0.399, p ≤ 0.01). In contrast the long distance movement showed no significant correlation with vegetation types (Pearson correlation test; 0.659, p ≤ 0.01 and Spearman correlation test; r = 0.09 p = 0.58). This study suggested that limited movement of hatchlings and juveniles (inter-valley and inter-island) could impact gene flow among subpopulations. Managers should consider appropriate strategies in maintaining genetic variability source to prevent inbreeding of isolated populations.

vi ABSTRAK Tujuan daripada kajian ini ialah untuk menyelidiki pola-pola dalam ekologi spasial pada tetasan dan anak Biawak Komodo (Varanus komodoensis) di Taman Negara Komodo, Indonesia. Di dalam penyelidikan ini, kaedah Capture-Mark-Release and Recapture telah dijalankan di 10 lembah utama ke atas 4 pulau di TNK daripada 2003 sehingga 2005, manakala ‘radiotracking’ dijalankan di Loh Liang, pulau Komodo, antara bulan Mac sehingga Julai 2004 dan 2005. Didapati bahawa jarak perpindahan tetasan biawak Komodo lebih rendah (32.62 ± 12.67 m/hari) dari pada anakan (129.14 ± 41.71 m/hari; t-test t1,9=-3.014, p=0.015). Tetasan memiliki luasan Minimum Convex Polygon yang secara nyata lebih kecil (3.02 ± 0.73 ha) dari pada anakan (24.31 ± 8.38 ha; t-test; t1,9 = -3.658, p = 0.006). Terdapat 5 dari pada 6 kes overlap wilayah aktiviti (4.84 – 91.01 %). Tetasan bersifat arboreal (97.70%) dari pada anakan yang cenderung terestrial (71.0%) (Chi square test; x2 = 239.22, p ≤ 0.001). Tetasan lebih banyak teramati pada ketinggian yang rendah (> 25 m) dari pada anakan yang lebih banyak teramatai pada ketinggian (25 – 50 m; Chi square test; x2 = 25.127, p ≤ 0.001). Tetasan menunjukkan kecenderungan untuk menggunakan pohon asam Tamarindus indica tree (45.37 %) sebagai tempat berteduh, sedangkan anakan lebih memilih celah-celah diantara batu karang (51.77 %). Terdapat pula korelas yang nyata antara jarak perpindahan skala besar dengan luasan lembah (Pearson correlation test; r = -0.125, p ≤ 0.001) dan dengan tingkat kemiringan tebing (Spearman correlation test; r = -0.399, p = 0.007), akan tetapi terdapat korelasi yang tidak nyata dengan jenis vegetasi (Spearman correlation test; r = -0.399, p = 0.007). Daripada kajian ini menunjukkan bahawa sedikitnya perpindahan antara lembah mahupun antara pulau pada tetasan dan anakan biawak Komodo dapat berdampak kepada rendahnya pertukaran variasi gen pada populasi pulau. Pengurus mesti merancang strategi pengurusan tetasan dan anakan Biawak Komodo untuk menyokong pertukaran sumber variasi gen bagi populasi terisolasi.

vii CONTENTS

Page

DECLARATION

iii

ACKNOWLEDGEMENTS

iv

ABSTRACT

v

ABSTRAK

vi

CONTENTS

vii

LIST OF FIGURES

x

LIST OF TABLES

xi

CHAPTER I

GENERAL INTRODUCTION

1

CHAPTER II

LITERATURE REVIEW

2.1

Spatial Ecology Studies in Free Ranging Animals

4

2.2

Systematics and Distribution of the Komodo Dragons

5

2.3

Present Status of the Komodo Dragons

8

2.4

Biology, Ecology, and Reproduction of the Komodo Dragons

9

2.5

Biology and Ecology of Juveniles

11

2.6

Previous Ecological Studies on the Komodo Dragons

12

CHAPTER III

GENERAL METHODOLOGY

3.1

Study Site

14

3.1.1 Biogeographical setting 3.1.2 Selected study sites

14 16

Field Techniques

20

3.2.1 Juvenile classification 3.2.1 Radiotelemetry 3.2.3 Mark-recapture techniques 3.2.4 Baited box-trapping technique

20 21 22 23

3.2

viii

3.3

3.2.5 Baited Pipe-trapping technique 3.2.6 Noosing and Hand-capture technique 3.2.7 Nest enclosure traps

24 25 25

Data Analysis

26

3.3.1 Spatial movement and activity area 3.3.2 Habitat use 3.3.3 Long distance movement

26 27 27

CHAPTER IV

A COMPARISON OF DAILY MOVEMENT PATTERNS, ACTIVITY AREAS AND HABITAT USE BETWEEN HATCHLING AND JUVENILE KOMODO DRAGONS

4.1

Introduction

28

4.2

Materials and Methods

29

4.2.1 4.2.2 4.2.3 4.2.4 4.2.5

29 30 30 31 32

4.3

Study site Studied animals Radiotelemetry technique Habitat assessment Data analysis

Results

35

4.3.1 Patterns of movement 4.3.2 Size of activity areas 4.3.3 Patterns in habitat use 4.3.4 Shelter sites selection

35 40 40 42

4.4

Discussion

44

CHAPTER V

ASSESSING LONG DISTANCE MOVEMENT OF HATCHLING AND JUVENILE KOMODO DRAGONS

5.1

Introduction

49

5.2

Materials and Methods

51

5.2.1 Study sites and capture technique 5.2.2 Data analysis 5.2.3 Statistical analysis

51 53 54

5.3

Results

56

5.4

Discussion

57

ix CHAPTER VI

GENERAL DISCUSSION

6.1

General Discussion

62

6.2

Recommendations

63

CHAPTER VII

CONCLUSION

REFERENCES

68

x LIST OF FIGURES No. Figure 2.1

3.1

4.1

4.2 4.3

4.4

5.1

Page Distribution of Varanus komodoensis. Grey areas represent the current distribution; black areas represent areas that were identified as part of the distribution by Auffenberg (1981); Hatched areas indicated where V. komodoensis has been reported by villagers.

7

Study sites across the four islands of Komodo National Park. Numbers are dedicated to show the locations; 1. Loh Sebita; 2. Loh Liang; 3. Loh Lawi; 4. Loh Wau; 5. Loh Buaya; 6. Loh Baru; 7. Loh Tongker; 8. Loh Dasami; 9. Nusa Kode; 10. Gili Motang.

19

Movement patterns of hatchling Komodo dragons. Arrows indicate starting point and general direction of movements. Letter refers to hatchlings ID as follow; a) 64D4C0E, b) 63DFB2A, c) 64E4218, d) 63C1383.

37

Movement patterns of two juvenile Komodo dragons (a: 639E332, b: 63D9C4B). Circles indicate shelter sites.

38

Activity area overlaps of six juvenile Komodo dragons as calculated by MCP (a) and 50% Adaptive Kernell (b). Numbers refer to juvenile ID as follow: 1) 64CF2A0, 2) 639E332, 3) 64E761C, 4) 64E2E95, 5) 63DE6F1, 6) 63D9C4.

39

Differences in terrestrial and arboreal habitat use by hatchling and juvenile Komodo dragons (a). Figure b depicts the relationship between body size (SVL) and arboreal activity in the radio-tracked Komodo dragons.

41

Frequency of annual movement for hatchling (a), daily and annual movement for juvenile (b, c).

55

xi LIST OF TABLES Table

Page

2.1

Local names for Komodo dragon.

6

2.2

Average density of Varanus komodoensis in Komodo National Park (KNP) and Flores Island.

8

Size of each island within KNP and it’s vegetation cover (in km2).

15

Range of measurements applied in classifying hatchling and juvenile Varanus komodoensis in this study. Measurement data were obtained during the mark-recapture study (20032005).

21

Summary of SVL, weight, number of observations, and fixes of radio-tracking study in hatchling and juvenile Komodo dragons.

31

Detail of results on radio-tracking study of hatchling and juvenile Komodo dragons.

36

4.3

Percentages of overlap on activity areas in juveniles.

36

4.4

Frequency of elevation preferred by hatchling and juvenile (%).

43

4.5

Major tree preferences used by hatchling and juveniles (%).

43

4.6

Total number of tree species and mean values of tree parameters used, and animal position on tree.

43

5.1

Total number of tagged animals for each year.

52

5.2

Distance of movement of juvenile Komodo dragons (m)

58

5.3

Topographical barrier’s score of each study area.

58

5.4

Distance between islands in Komodo National Park.

58

3.1 3.2

4.1

4.2

CHAPTER I

GENERAL INTRODUCTION

The Komodo dragon (Varanus komodoensis) is the largest extant lizard in the world (King & Green 1999; Mattison 1992; Pough et al. 2001). This species lives in a relatively small range of distribution in the wild. Komodo dragons can be found on the islands of Komodo, Rinca, Nusa Kode, Gili Motang, and the western coast of Flores (Ciofi et al. 2002; Ciofi & de Boer 2004), and were previously known on Padar Island. Currently, four of these populations are located within the boundary of Komodo National Park (PHKA 2000). Flores is the largest island within the Komodo dragon’s distribution and contains two nature reserves: Wae Wuul on the west coast and Wolo Tado on the north coast (Sastrawan & Ciofi 2002). It is evident that the dragon populations in these parks are more secure than those outside of the parks, given that key threatening processes, including habitat loss, altered fire regimes and competition for key prey with humans, are largely absent within the park (Jessop et al. 2004). The range of the Komodo dragon has decreased significantly over the last 3 decades due to several threatening processes including the suspected decline of large prey, such as Timor deer (Cervus timorensis) and anthropic habitat fragmentation and disturbances (Ciofi et al. 2002; Ciofi & de Boer 2004). Degradation of the environment is considered to be a major threatening process that could influence the viability of the extant dragon populations (Jessop et al. 2004).

Due to its vulnerability and its restricted distribution in the wild, Varanus komodoensis is listed as “vulnerable” in the IUCN Red Data Book, and is on Appendix I of CITES (Ciofi et al. 2002). The Komodo dragon is also protected by

2 Indonesian law, including the need for a presidential decree to transfer any individuals of this charismatic species out of Indonesia.

There are a number of key research areas that require further investigation to facilitate Komodo dragon management and conservation. An important component of Komodo dragon management is to understand the spatial requirements and habits, including movement, activity area, behavior, and habitat use (Phillips 1995; Brill et al. 1995). These spatial aspects of an animal’s ecology are the key to understanding important processes such as dispersal, habitat partitioning and reproduction and how they influence population structure. Understanding these spatial aspects of dragon ecology is also invaluable in the conservation of this threatened species.

Studies in spatial ecology are often undertaken to calculate estimates of individual movement, home range, habitat utilization (i.e. Fitzgerald et al. 2002; Piepgras & Lang 2000), diet (Thompson & Thompson 2001; Whitaker & Shine, 2003), and responses to anthropic habitat changes (Pearson et al. 2005). Knowledge of an animal’s home range is also important for management purposes (Caley 1997). Boudjemad et al. (1999) related how habitat modification by anthropic causes could directly affected demography and movement capacity of wildlife. Further, habitat change can influence dispersal or foraging strategies (i.e. aspects of spatial ecology), which can have an impact on the fitness of individuals and, ultimately, the population as a whole (Greenwood & Swingland 1984).

A number of spatial studies have been conducted and have described activity, area size, movement, and behaviour of Varanid lizards (Ibrahim 2002; Thompson et al. 1999; Thompson 1992) is relation to patterns of physiology, reproduction and demography (Christian et al. 1995; Christian & Weavers 1994; James 1996; Phillips 1995). These spatial studies focused on adults, and thus little is known concerning juveniles and hatchlings. Spatial studies on Komodo dragons by Auffenberg (1981) and Sastrawan and Ciofi (2002) focused on the home ranges of adult dragons only.

3 In the present study, spatial ecology was defined as the interaction between young Komodo dragons with environmental conditions. It is hypothesized that environmental conditions will influence the spatial ecology of young Komodo dragons. The objectives of this study are to: 1) determine the patterns of daily movement and the activity areas; 2) identify patterns of habitat use; and 3) assess long distance movement ability in hatchling and juvenile Komodo dragons. Results of this research are anticipated to contribute valuable information on the biology of hatchling and juvenile Komodo Monitors, that can be of benefit to the management practices of the park, particularly for this species and its habitat.

CHAPTER II

LITERATURE REVIEW

2.1

SPATIAL ECOLOGY STUDIES IN FREE RANGING ANIMALS

Habitat loss and fragmentation are currently the most serious threats to wildlife worldwide, so it is important to understand how patterns and processes of landscape change will cause individual populations and species to respond to these broad-scale modifications (Blumstein & Fernandez-Juricic 2004; Collinge 2001). Spatial heterogeneity processes directly affect ecological systems (Gardner et al. 1989). The spatial arrangement of individuals within a population will reflect aspects of its behavior and ecology, and is important in determining population persistence and gene flow within and between sub-populations (Brown & Downhower 1988; Johnson 2000). Thus, the dynamics of an animal population depends not only on birth and death rates, but also on an animal’s ability to move into or out of a population (Dasmann 1964). Determining the number of individuals persisting in an area is a basic question in ecology, but it is more important to understand how an animal responds to changing landscape conditions, regardless of whether it is at the individual, population or community level (Lawson et al. 2006).

Krebs (1999) pointed out that spatial ecology as a science aims to understand the ecological processes that determine the location of individuals, which are rarely spread evenly over the landscape. Collinge (2001) concluded that spatial ecology is an ecological study, which centers upon understanding how landscape configurations influence the community and population dynamics of organisms. Spatial ecology is at the very core of the science of ecology (Boyce & McDonald 1999). Whitaker and Shine (2003) stated that studying spatial ecology can contribute at least three potential

5 benefits; first, a better understanding of movement and habitat selection by the animal, second, giving information regarding animal-human interactions, and third, as an aid in assessing the response and role of an animal in regards to their habitat. Collinge (2001) emphasized that empirical studies in spatial ecology beneficially links conservation biology research to practical mechanisms for species management and conservation planning. In studying spatial ecology, authors included studies of dispersal (e.g. Olsson & Shine 2003), movement and activity area, habitat use, activity patterns (Fitzgerald et al. 2002; Piepgras & Lang 2000), diets (Thompson & Thompson 2001; Whitaker & Shine 2003), and anthropic habitat changes (Pearson et al. 2005; Martin et al. 2001; Fitzgerald et al. 2002).

Dispersal is the movement of an individual from its natal area to an unoccupied and suitable area within which it is able to establish its own home range. Caughley and Sinclair (1994) emphasised that migration is not the equivalent of dispersal. Greenwood and Swingland (1984) described dispersal as being caused by the need for an individual to search for food sources. Lebreton et al. (2003) studied the importance of dispersal as a mechanism in reproduction.

It is essential in studying spatial ecology to investigate dispersal patterns. Dispersal is recognized as a key process in ecology, evolution, and conservation and it is important to understand the consequences to an animal’s behaviour as it responds to the habitat (van Dyck & Baguette 2005). Dispersal can affect the dynamics and persistence of populations, distribution and abundance, community structure, gene flow, local adaptation, speciation, and the evolution of life-history traits (Lebreton et al. 2003; Roper et al. 2003). Thus, dispersal is one of the most critical events in the life of most animals and one of the most important processes affecting the ecology and evolution of populations (Roper et al. 2003).

2.2

SYSTEMATICS

AND

DISTRIBUTION

OF

THE

KOMODO

DRAGONS

The Komodo dragon, Varanus komodoensis, was described for the first time by Major Peter A. Ouwen in 1912 (Auffenberg & Auffenberg 2002; Dunn 1927). This

6 giant lizard species was placed in the genus Varanus, family Varanidae, order Squamata, Class Reptiles (Mattison 1992). Varanus salvadorii from Southern New Guinea and V. varius from Southeastern and Eastern Australia are believed to be the sister groups of V. komodoensis (King et al. 2002; Molnar 2004). The closest congeneric species occupying the same region is the Monitor lizard, V. salvator salvator (Auffenberg 1981).

Auffenberg (1981) reported that this species was called the “Ora” by the local people of Komodo, Rinca, and West Manggarai. There are several local names described by Auffenberg (1981) from across its distribution in the Lesser Sunda region (see Table 2.1). The name “Komodo” was taken from the name of the island where the first specimens were taken, and which means “rats” (Dunn 1928).

Table 2.1 Local names for Komodo dragon Local name

Region

Ora (also hora, lawora) Manggarai Buaya darat (= land crocodile) Manggarai Rugu (= Ora) Si (also ugu; = lizard) Lio (also ugu, = large monitor) Pendugu (Grandfather of Ora) Mbou (= Ora)

Komodo, Rinca, West Komodo, Rinca, West Central Manggarai Central Manggarai Central Manggarai Central Manggarai Central Manggarai

Source: Auffenberg 1981 Even though the Komodo dragon is the largest lizard in the world, this species has the smallest range of any large carnivore (King & Green 1999; Mattison 1992; Pough et al. 2001). In the early studies of the Komodo dragon, this species was found in the heart of the Lesser Sunda region on the islands of Komodo, Rinca, Padar, Gili Motang, Gili Dasami (also known as Nusa Kode), and the Western coast of Flores Island (Dunn 1928; Fig. 2.1). Five of the islands are within the boundary of Komodo National Park (PHKA 2000; Fig 2.1). In studies conducted after 1991, this species could not be found on Padar Island (Ciofi & de Boer 2004; Jessop et al. 2004; Sastrawan & Ciofi 2002).

7

Figure 2.1

Distribution of Varanus komodoensis. Grey areas represent the current distribution; black areas represent areas that were identified as part of the distribution by Auffenberg (1981); hatched areas indicate where V. komodoensis have been reported by villagers.

Source: Redrawn from Sastrawan and Ciofi 2002.

8 2.3

PRESENT STATUS OF THE KOMODO DRAGONS

Based on population surveys conducted by the park authority, there were approximately 2405 Komodo dragons living within Komodo National Park in 1998 (PHKA 2000, unpublished report). Ciofi and de Boer (2004) estimated that the population density of dragons on Flores was more than 60% lower than that reported for Komodo National Park (Table 2.2.). Jessop et al. (2006 in press) estimated that the dragon population on Gili Motang Island has the lowest density of dragons of all the inhabited islands within the park (see Table 2.2).

The disappearance of resident Komodo dragons on Padar Island probably stemmed from the decline of Timor deer (Cervus timorensis) populations due to illegal hunting (Ciofi 1999; Ciofi & de Boer 2004). Pet and Subijanto (2001) reported that there were at least 3 cases (37.5 %) of deer hunting in Komodo National Park that had been sent to court during 2000-2001. Ciofi et al. (2002), Ciofi and de Boer (2004), and Primack (2004) stated that fragmentation and habitat disturbance as a result of the high population growth of humans are the main factors affecting Komodo dragon populations on Flores.

Table 2.2

Average density of Varanus komodoensis in Komodo National Park (KNP) and Flores Island.

Location

Population density

KNP Komodo Rinca Nusa Kode Gili Motang Flores

1 / 33.25 km 13.7 ± 1.67 / km 19.6 ± 3.13 / km 5.1 ± 0.61 / km 3.2 ± 0.23 / km 1 / 170.0 km

Number of sites 4

7

Source: Modified from Ciofi & de Boer 2004; Jessop et al. 2006 unpublished data. Even though the Komodo dragon is not threatened by the leather trade, like the congeneric Water Monitor (V. salvator), and is considered ‘dangerous’ to humans (King et al. 2002; Shine et al. 1996; Ellis 1998), hunting and trade in this species has

9 been occurring for a long time. Since the 1930’s Komodo dragons and their eggs have been hunted illegally for zoo collections and for traditional medicine (Primack et al. 1988). Hien (2003) reported that the local people of Riung, Northwest Flores, claimed that they once illegally caught 50 live specimens of the Komodo dragon for a foreigner. However, the widespread hunting and trading of other reptiles including varanids, for their skins and for food (e.g. Shine et al. 1996) should be considered a potential threat to the Komodo dragon.

The Komodo dragon is protected by international conventions; it is listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and is classified by the International Union for the Conservation of Nature Resources (IUCN) as “vulnerable” due to its demographic decline and limited distribution (Ciofi et al. 2002). The World Conservation Monitoring Center (WCMC) also listed the Komodo dragon as “Rare” due to it’s restricted distribution (Ellis 1998). This species is protected in Indonesia under Act no. 5, on Conservation of Biological Resources and Their Ecosystems,1990,; and Government regulation no. 7, on Protected Wild Flora and Fauna, 1998. Primack (2004) included the Komodo dragon in his discussion on “conservation priorities” as he considered that this species met all the criteria of distinctiveness, endangerment, and utility.

2.4

BIOLOGY, ECOLOGY, AND REPRODUCTION OF THE KOMODO DRAGONS

Compared to other species in the family Varanidae, Varanus komodoenis has an extremely large body size. Adults can reach up to 304 cm in total body length and weigh up to 81.5 kg (Jessop et al. 2006 unpublished data). Sastrawan and Ciofi (2002) recorded the largest Komodo dragon in their field study as being about 300 cm in length and weighing about 69 kg. Auffenberg (1981) recorded his largest specimen caught as being 260 cm in length and 54 kg in weight. This is similar in length to the largest specimens of its sister species, the Papuan monitor V. salvadorii, which reached about 265 cm in length (Horn 2004). Another large varanid species, occuring

10 on the islands of Java, Bali and throughout Lesser Sunda region, V. salvator may reach up to 218 cm in length and weigh up to 25 kg (Gaulke & Horn 2004; Horne & Gaulke 2004).

Hatchlings of V. komodoensis average 30.4 cm in total length and 0.08 kg in weight, and are considerably longer at hatching than other large varanid species (Auffenberg 1981). Ciofi (2004) recorded that hatchling V. komodoensis average 42 cm in total length and 0.10 kg in weight. Hatchling V. salvadorii possibly reach up to 49 cm in total length and 0.55 kg in weight (King & Green 1999).

Komodo dragons can be found from sea level up to about 800 meters in altitude, mainly in tropical dry and moist deciduous monsoon forests (Ciofi 2004). Indeed, this species is generally distributed over entire islands within KNP and western coastal on Flores but is rarely found above 500 meters (Auffenberg 1981).

All varanids are insectivores or carnivores. Unlike other varanids that rely on smaller prey species, Komodo dragons are able to feed on larger vertebrate species, such as the Timor Deer (Cervus timorensis), water buffalo (Bubalus bubalis), or small wild boars (Sus scrofa). Adult Komodo dragons mostly rely on a sit-and-wait hunting strategy to catch their prey (Auffenberg 1981; Green et al. 1990; King & Green 1999; Pough et al. 2001). Hatchlings and juveniles, however, feed on a diverse diet of insects, small lizards, snakes and birds, and use more active hunting strategies than adults (Auffenberg 1981; Ciofi 1999; Mattison 1992).

Female Komodo dragons are known to breed when they reach a body weight of around 20 kgs (King & Green 1999). Females begin nesting in August, as determined by the presence of recent digging activity on the nest, or by repeated observation of individuals in association with the nest during the nesting period. The nesting period is from August through November, with egg deposition occurring in September (Ciofi 1999; Jessop et al. 2004). Up to 38 hatchlings will emerge from the nest at the beginning of the dry season (Auffenberg 1981; Jessop et al. 2006

11 unpublished data). This early life-stage is dominated by high mortality. Cannibalism among Komodo dragons has been observed and was calculated to comprise 8% of adult dragon scats (Auffenberg 1981). Cannibalism has also been recorded in other Varanids, such as V. griseus, V. gouldii and V. gigantheus (King & Green 1999).

2.5

BIOLOGY AND ECOLOGY OF JUVENILES

Generally, mortality in lizards is highest during the first phase of their life because they are more vulnerable to predation (Mattison 1992). Poor maternal body condition and stress can decrease the dispersal tendency of juveniles (Meylan et al. 2002). Typically, natural populations show substantial variation, in locomotor performance and body size, which is related to offspring survivorship (Clobert et al. 2000). Thus, the growth and survivorship of offspring in reptiles is greatly affected by the animal’s environment (i.e. Brockelman 1975; Gans & Pough 1982).

Incubation temperature is known to contribute greatly to the quality of emerging hatchlings and affects their survivorship. Cold temperature during incubation can negatively effect hatchlings and hot temperatures can positively effect hatchlings (Elphick & Shine 1998; Phillips & Packard 1994; Qualls & Andrews 1998). This pattern is complex, however, as higher incubation temperature will result in earlier hatching but produce lighter and smaller hatchlings than lower temperature, which produce larger offspring that tend to survive better (King & Green 1999). Du and Ji (2003) reported that moderate temperatures produced optimum size, locomotor ability and success of hatchlings in soft-shelled turtle, while Ji and Du (2000) reported a similar pattern in colubrid snakes. In a further study on lizards, the only discernible influence on juvenile phenotypes was their rearing environment (Qualls & Shine, 2000). Brockelman (1975) found that a wide variety of factors can affect optimal body size and the ability to process energy effectively, and these were also affected by the process of competition, which the offspring must face before and during maturity.

12 Most juvenile reptiles leave the natal area in which they were born and move into new habitats that are not already occupied or to avoid cannibalism by adults (Pough et al. 2001). Greenwood (1984) noted that natal dispersal among juveniles is also considered as a mechanism to avoid future inbreeding. Heatwole (1976) and Sarno et al. (2003) described natal dispersal as being driven by the competition for food resources and territories with adult.

Dispersal is a mechanism for survival and is a consequence of permanent movement away from the natal site (Brown & Downhower 1988). Animals will exploit available resources once they are out of their natal sites (Greenwood & Swingland 1984). Pelletier et al. (2003) described how immature turtles immediately swam towards the ocean and steadily traveled long distances once released into the water. Hatchling of varanids tend to climb trees and spend most of their time in the upper strata of trees once they emerged from the underground nests (Auffenberg 1981; Bohme et al. 2004; Ciofi 2004; King & Green 1999).

2.6

PREVIOUS ECOLOGICAL STUDIES ON THE KOMODO DRAGONS

The first scientific study on the Komodo dragon was conducted by Major Peter A. Ouwen, director of the Zoological Museum in Buitenzorg (now Bogor), Java, in 1912 (Auffenberg & Auffenberg 2002). Ouwen described the species for the first time. Later, Dunn (1927 & 1928) conducted the first significant observations and gave the initial information on the habitat and distribution of Komodo dragons. Auffenberg (1981) contributed to the first comprehensive study on the ecology and behavior of this species. On the basis of 13 months of field observations, Auffenberg (1981) provided the base line information on aspects of the Komodo dragon’s ecology and behavior. The most recent field study on the Komodo dragon was conducted by Jessop et al. (2006 unpublished data). Since 2002, they undertook a broad scale investigation in the ecologyl and demography of the Komodo dragon, which has provided important information and instigated a program to monitor population trends. Although numerous field studies on the ecology of Komodo dragons have been conducted, yet there are no detailed studies on the ecology on juvenile Komodo dragons (Auffenberg & Auffenberg 2002). Walsh et al. (2002) studied growth in

13 juvenile Komodo dragons, whilst Lemm (2004) reported a relationship between growth and nutritional treatment in captivity.

Field and captive studies on this creature, including work on growth, chromosomes, physiology, genetics, ecology and social behaviour, parasites, microbiology, conservation and management, have provided valuable information to science and to ensure effective management of the species (Ciofi et al. 2002). The long-term management and conservation objectives underpinning survival of this species will be to maintain a genetically viable, self-sustaining, and free-living Komodo dragon population. Information on reproduction and broad scale ecology of this species is needed to support the management authority responsible to protect it, and, as pointed out by Jessop et al. (2004), information on offspring survivorship are vital for management planning to ensure the maintenance of this unique species in the wild.

CHAPTER III

GENERAL METHODOLOGY

3.1

STUDY SITE

3.1.1

Biogeographical Setting

The study was conducted within the Komodo National Park, East Nusa Tenggara, Indonesia, approximately 500 km east of Bali. The Park lies in the Lesser Sunda region between Flores Island and Sumbawa Island (8°35’40” S and 119°25’51”E), encompassing two main islands; Komodo and Rinca; three smaller islands, Padar, Gili Motang and Nusa Kode, and numerous smaller adjacent islands. Komodo National Park established by the government of Indonesia in 1980, enhancing its status from Wildlife Reserve in 1970. Before declared as national park, this park was declared as a Man and Biosphere Reserve by UNESCO in 1977. Further, in 1991 UNESCO designated this park as a World Heritage Site. The park was initially established to conserve the unique Komodo dragon (Varanus komodoensis) and was identified by both WWF and Conservation International as a global conservation priority area. This area is a transitional zone between the Australian and Asian fauna and flora, containing elements of both (PHKA 2000).

The park encompasses the extant distribution of the endangered species of the Komodo dragon and is approximately 1817 km2 in size encompassing both marine (1214 km2) and terrestrial (603 km2) habitat (PHKA 2000). Komodo and Rinca are the two largest island, followed by Padar, Gili Motang, and Nusa Kode. Most of the islands are mountainuous (the highest peak is

800 m asl on Komodo Island),

15

combining a mostly grass-covere rugged topography, with variuous size of flat valleys on the lower elevation (up to 50 m asl) (Dunn 1928; Monk et al. 1997).

Komodo Island is the largest island with the highest peak reaching 800 m asl and is mostly covered by grassy savanna habitat (59.38%) (Table 3.1). Rinca the second largest island is also predominantly covered by savanna habitat (55.02%) and the highest peak is 712.5 m. Padar, the third largest island, has the highest percentage cover of savanna habitat (93.48%) amongst other large islands. The other two main islands, Gili Motang and Nusa Kode are predominantly covered by open deciduous forest (79.96% and 84.33%, respectively). The other numerous small islands are predominantly covered by savanna grass.

There are four existing settlement within the park (PHKA 2000), namely Kampung Komodo (Komodo Island), Rinca, Kerora (Rinca Island), and Papagarang (Papagarang Island). The settlements were established prior to 1980, before the area declared as national park. Total population of these settlements was estimated approximately 2300 people in 1999. Table 3.1 Size of each island within KNP and it’s vegetation cover (in km2). Type of vegetation KOMODO cover (km2) 311.59 Island’s area 211.22 Beach Line 3.01 Mangrove Forest 185.02 Savanna Open Deciduous 79.29 Forest Closed Deciduous 38.63 Forest 8.65 Quasi Cloud Forest

14.09 36.16 0.40 13.17

GILI MOTANG 9.48 16.11 0.00 1.37

NUSA KODE 7.33 15.66 0.04 1.15

64.88

0.92

7.58

6.18

27.24 0.00

0.00 0.00

0.53 0.00

0.00 0.00

RINCA

PADAR

204.78 203.64 6.50 112.66

Source: Jessop et al. 2006 unpublished data.

The climate is dry and is influenced by monsoons and trade winds. Rainfall varies with the elevation, averaging less than 500 mm a year, with peak values between December and February (Monk et al. 1997). Jessop et al. (2006 unpublished

16

data) classified the vegetation cover of each island, with modifications based on classification by Auffenberg (1980) as shown in Table 3.1:

-

Mangrove Forest (MF) is a community of mangroves, flooded daily by tides, located along the shoreline. This habitat is dominated by Rhizophora sp. and Lumnitzera.

-

Savanna (SF) habitat covered more area of the largest islands of Komodo, Rinca, and Padar and mostly dominated the hilly areas. This habitat is dominated by the grass species Eulalia leschenaultiana. Common trees found at the lower altitude are Borassus filiformis, Zyzypus sp., and Tamarindus indica.

-

Open Deciduous Forest (ODF) is a tropical monsoon forest which is dominated by Tanarindus indicus, followed by Sterculia foetida. This forest mostly exists across the big valleys (i.e. Loh Liang, Loh Sebita). ODF is characterized by the more open canopy. Komodo dragons are mostly found within this type of forest.

-

Closed Deciduous Forest (CDF) is a tropical monsoon forest similar to the ODF but with a denser canopy. CDF mostly exists in the deeper parts of valleys and has higher elevation as compared to ODF.

-

Quasi Cloud Forest (QCF) is only found above 500 m asl. This forest has a moisture and cooler climate and is characterized by moss-covered rock, bamboo groves, and rattan.

3.1.2

Selected Study Sites

The overall study was conducted across 10 sites on four islands, but the radio telemetry study was only done in Loh Liang. The study sites are; Loh Sebita, Loh Liang, Loh Lawi, and Loh Wau on the Komodo Island, Loh Buaya, Loh Baru, Loh

17

Tongker, and Loh Dasami on Rinca Island, Nusa Kode Island, and Gili Motang Island. The description of each study site is as follows (Figure 3.1);

1) Loh Sebita (SB) (8º32’ N, 119 º32 E). This site is located on the east coast of Komodo Island. The valley is characterized by a dense mangrove forest stretching along the east coast of the valley. Towards the west, the topography increases gently from sea level to about 735 m asl, the second highest peak of the island. To the south uplifted rugged mountain stands delimit the valley with smoother hills to the north. Vegetation in Loh Sebita is dominated by the open deciduous forest type.

2) Loh Liang (LG) (8º34’ N, 119º29 E). This site is located at the north-east part of the island, approximately 6 km south of Loh Sebita. Loh Liang is a wide valley and is characterized by ODF. CDF exists along the northern to western parts. This valley is delimited by smoother hills to the west and north, which rise from sea level to the highest altitude of the island (800 m asl to the west and 740 m asl to the northwest). To the East, this valley is delimited by the rugged mountain stands. Vegetation in Loh Liang is dominated by the open deciduous forest type, except in the northern deeper valley, close dense forest exists.

3) Loh Lawi (LW) (8º36 N, 119º26 E). This site is located at the center of Komodo Island, approximately 7 km southern of Loh Liang. This valley is characterized by a long (approximate 6 km from the coast line) and narrow area, delimited by rugged mountatins to the south, west, and north. To the east, Loh Lawi is covered by a thick mangrove forest along the south coast. Across the valley, open deciduous forest is predominantly.

4) Loh Wau (WA) (8º41’ N, 119º26’ E). This site is located on the south of Komod Island, approximately 17 km from Loh Liang. The valley is delimited by rugged mountainous topography to the west and smoother hills to both the south and north. The close dense forest vegetation type is predominantly in this very small valley.

18

5) Loh Buaya (BY) (8º39’ N, 119º43’ E). This site is located on the northern part of Rinca Island. This valley has a smooth topography. Savanna is predominant in the valley with a small open deciduous forest to the middle of the valley.

6) Loh Baru (BR) (8º43’ N, 119º41’ E). This site is located to the east of the island, approximately 9 km south of Loh Buaya. The local people occupied this valley before the park was established. Later, the settlements moved to the nearest villages; Kerora and Rinca village. In Loh Baru agricultural crops predominantly in the valley, while to the deeper part of the valley open deciduous forest exists. The Loh Baru site also includes Loh Baru valley and Sok Niu valley, which is located 2 km north of Loh Baru. Komodo dragons are known to move reoutinely between these two valleys. To the west and south, Loh Baru is delimited by rugged mountains which lead to the highest peak altitude of the island (712.5 m asl).

7) Loh Tongker (TK) (8º45’ N, 119º43’ E). This site is located to the Southeastern of Rinca Island, approximately 12 km southern Loh Buaya. This small and narrow valley is predominantly covered by open deciduous forest. Loh Tongker is delimited by rugged and steep hills.

8) Loh Dasami (DS) (8º46’ N, 119º39’ E). This site is located on the southern part of Rinca Island, approximately 15 km southern Loh Buaya, and is characterized by a very closed dense forest. This small valley is delimited by a rugged mountainous terrain to the west, north and east, and the highest peak has an altitude of 712.5 m asl.

9) Nusa Kode (NK) (8º47’ N, 119º39’ E). This site is located as a small island is southern Rinca Island, approximately 1.5 km across Loh Dasami valley. Nusa Kode is a rugged mountainous island and has few small and narrow valleys. The island is predominantly covered by open deciduous forest from sea level to the peak (400 m asl). Savanna exists on the eastern side of the island.

19

BORNEO

KOMODO

1

2

3

5 4

PADAR

6

RINCA 8 7

N

0

Figure 3.1

5

10 Kilometers

9

10

Study sites across the four islands of Komodo National Park. Numbers are dedicated to show the locations; 1. Loh Sebita; 2. Loh Liang; 3. Loh Lawi; 4. Loh Wau; 5. Loh Buaya; 6. Loh Baru; 7. Loh Tongker; 8. Loh Dasami; 9. Nusa Kode; 10. Gili Motang.

20

10) Gili Motang (GM) (8º48’ N, 119º47’E). This mountainous island is located 8 km southeast off Rinca Island, and 3 km southwest off Flores. This isolated island is predominantly covered by open deciduous forest dominated by Schoutenia ovata. Along the western to the southern part of the island, savanna exists up to the peak (425 m asl) with small closed dense forest on the peak. This island has received less attention as compared to the other places within the park in regards to conservation management (Jessop et al. 2006 in press).

3.2

FIELD TECHNIQUES

3.2.1

Juvenile Classification

Hatchlings among species in Varanids vary greatly in size (King & Green 1999). They range from 18 grams in weight and approximately 17 cm in length in V. rosenbergi, 80 to 127 grams in weight and are about 30 cm in length in V. komodoensis. Auffenberg (1981) found that average total length of Komodo dragon hatchling was 30.4 cm in SVL and weight 80.3 grams, and were considerably longer and larger than the other large Varanid species.

The juvenile in Komodo dragon were estimated below maturity sexual age, which is estimated 5 years (King & Green 1999). Lemm et al. (2002) defined those juvenile Komodo dragons which less than three years had 38 – 40 cm in SVL and 0.75 – 1.30 kg in weight. Large Komodo dragons (>2.3 m in total length and >38 kg in weight) are likely to be males, but younger and smaller animals are difficult to sex (Jessop et al. 2006 unpublished data; Auffenberg 1981). Within this study, hatchling was defeined as recently hatched animal (below one year), while juvenile was above yearling animal. Animal thus met all of the measurements ranges as shown in table 3.2 below were classified either as hatchling or as juvenile.

21

Based on the studies by Auffenberg (1981) and Ciofi (2004) juvenile of Varanus komodoensis is categorized as follow;

-

Hatchling Hatchling has a brown pattern with large, distinct orange spots on the dorsal region. Yellow stripes present on it’s neck to the dorsal region. Light yellowish spot pattern found on its four legs from the temporal region to the front. Front legs are brown with white flecks disposed in round, horizontal circles. The ventral part of the body is light yellow with large dark spots. Tail has some light yellow strip circling.

-

Juvenile Juvenile pattern is gradually lost with age. They still show a lighter skin color, but have a darker brown pattern. Small light yellow spot pattern still exists on its four legs. Tail has lighter color (as compared to hatchlings) strip circling.

Table 3.2.

Range of measurement applied in classifying hatchling and juvenile of Varanus komodoensis within this study. Measurement data were obtained during the mark-recapture study (2003-2005). Head Length (cm)

SVL (cm)

Weight (kg)

Hatchlings min max

3.50 6.00

16.00 30.00

0.040 0.400

Juveniles min max

6.50 13.50

35.00 80.10

0.600 10.000

3.2.2

Radiotelemetry

Radiotelemetry was used to determined habitat utilization by hatchling and the juveniles. Samuel and Fuller (1996) confirmed that radiotelemetry is a good technique in acquiring detailed and unique information on animal ecology, physiological

22

process, and the proximate causes of mortality. White and Garrot (1990) emphasized the use of radiotelemetry to investigate habitat requirements, and demography. Similar techniques have been demonstrated in studying spatial ecology of reptiles (i.e. Fitzgerald et al. 2002; Sastrawan & Ciofi 2002; Webbs & Shine 1997).

This radiotelemetry study was conducted during two four-month periods in 2004 and 2005 in Loh Liang, Komodo island, where total of twelve Komodo dragon were radiotracked. This study was conducted after the hatchling period, which is usually between Februarys to March, when the transition of rainy to dry season, which is usually between March to June. AVM transmitters (G3-1V), AVM receivers (LA12-Q), and AF Antronics Yagi antennas were used in the study. The transmitters were glued to the base of the tail of selected animals and are considered the best site for placement. Attaching transmitters on juveniles by means a harness (Sastrawan & Ciofi 2002) was not feasible.

Individual were located either by direct observation or triangulation techniques (White & Garrot 1990). During tracking, certain parameters for habitat type or tree visited by animals recorded as follows; habitat type, tree species, breast height diameter, and tree height. To measure tree height Suunto clinometer was used. Radiotracked animals captured using capture techniques as described below.

3.2.3

Mark-recapture Techniques

To provide information on annual movements of the hatchling and juvenile Komodo dragons, this research employed the Capture Mark Release and Recapture (markrecapture) method (Krebs. 1999; Lancia et al. 1996; White & Clark 1996). Similar methods had been employed by Clobert et al. (2000); Limpus and Walter (1980), and Magnusson (1979) in their studies.

Mark-recapture studies were conducted every year during 2003-2005 across 10 study sites within the Komodo National Park (Figure 3.1). This research is part of the long-term annual population and ecology study of the Komodo dragon within the

23

Komodo National Park, which is being conducted by the Center for Conservation and Research of Endangered Species, Zoological Society of San Diego since 2002 (Jessop et al. 2006 unpublished data). Hatchling and juvenile Komodo dragons were captured using several techniques; including nest enclosure traps (using metal sheeting fence), baited (box and enclosed-pipe) traps, noose or by hand. Following capture, for safety reasons, captured Komodo dragons were restrained either by electric tape or by rope on its four legs and mouth taped. Capture and measuring processes were no more than 30 minutes. No anesthesia was used in handling the animals. To avoid injury to animals, physical restraint in handling the animals within this study was followed Friend et al. (1996).

Each captured animal was paint-marked using fluorescent paint as an external marker and permanently marked with Passive Integrated Transponder (PIT) tag (Trovan ID100a) before release at the point of capture within 30 minute of capture. The PIT tags are encased in glass, encoded with 10 digits of alphanumeric code, 8 X 2 mm in size and were implanted using a plastic syringe and 12-g needle. This technique is believed to be superior to most tagging methodologies for marking reptiles (Nietfield et al. 1996). Every captured Komodo dragon was measured before release. The following data were collected from each hatchling and juvenile and all the measurements were taken in centimeter (cm) and taken to the nearest 0.5 cm, while weight was in kilogram (kg).

- Head Length (HL), - Head Width (HW), - Snout-Vent Length (SVL), - Ventral Total Body Length (VTL), - Tail Length (TL), - Tail Circumference (TC), - Weight (W),

24

3.2.4

Baited Box-trapping Technique

This study employed baited-box-trapping (Jessop et al. 2006 in press) to capture juvenile Komodo dragons. Baited box-trapping is effective to catch individual above yearlings. Several previous researchers (Ciofi 2002; Sastrawan & Ciofi 2002; and Ciofi & De Boer 2004) captured Komodo dragon for genetic, home range, and distribution study employed similar trapping method (baited wood-box traps).

Each trap (300 X 60 X 60 cm) was constructed from alloy and aluminum metal sheets with two open-ends with sliding doors. Only one door (front side) was kept open to allow animals to enter the trap. The front door was connected by a metal wire with bait at the other end of the wire. Each trap was baited with goat-meat, where two or three pieces were placed on the floor to attract the juvenile to enter and approach the hanging bait. The front door would close whenever the hanging bait was pulled.

Eight traps were placed along a line transect with an interval of 250 - 450 meters between traps depends on the terrain and covered the valleys as much as possible. Traps were checked twice a day (morning and afternoon session) and moved for every three days to allow for sufficient production of the volatile oils that were released as the bait decomposed. Trap locations were marked by GPS (Garmin Etrex Summit). Recaptured and resighted animal within the same trapping session in each location were recorded and considered as Within Trip Recapture or Resight.

3.2.5

Baited Pipe-trapping Technique

To capture hatchling, this study was also employing enclosed PVC pipes 1m in length and 0.1 m in diameter where the bottom side is closed. To attract the hatchling, this trap was baited using meat. Similar techniques were implemented with other reptiles species as reported by Mathies et al. (2001) and Schemnitz (1996). Each pipe-trap was placed on a tree in 100 m line transects at a 5 m distance and approximately 1–2 meter above ground to attract hatchling and avoid disturbance by bigger Komodo dragon. Pipe-traps were placed near the active nests to anticipate escaping hatchlings and near

25

ranger station of station where occasionally hatchlings were found every hatchling seasons.

3.2.6 Noosing and Hand-capture Technique

The noosing technique has been demonstrated by many authors, such as Olsson and Madson (2001) and Wapstra and Swain (2001). The noosing technique required two persons and relies on a systematic search. Searching was conducted opportunistically by foot and covered almost entire the valley. Noosing technique employed one 2 meters of woody “Y” stick with lasso.

3.2.7

Nest Enclosure Traps

Female Komodo dragons are known to begin nesting in August, (Jessop et al. 2004), and lay eggs in September (Ciofi 1999). Up to 40 hatchlings will emerge from the nest at the beginning of dry season (February to March) and weigh between 60–130 grams and are about 20-60 cm in length (Auffenberg 1981; Ciofi 1999; King & Green 1999).

This study also employed fenced-nest technique to capture emerged-hatchlings from nest. This technique only possible to employed in Loh Liang, Loh Sebita (Komodo Island) and Loh Buaya (Rinca Island) where a number of active nests were monitored from survey in the previous year. Hatchlings were captured by hand within fenced nests. Metal sheeting with height of approximate 80cm from ground was used to circling the nest. Size of the area in which covered by the fence varying depending on the size of the nest. To avoid hatchlings escaping by digging the soil, 10 cm of the lower part of the metal sheeting was pushed into the ground. Each fence was covered by fishing nets to avoid predation by birds. Fenced-nests were monitored daily from early February to the end of March which is considered hatchling season. Hatchlings were captured by hand immediately on emergence and measured and PIT tagged before released.

26

3.3

DATA ANALYSIS

The spatial ecology of juvenile Komodo dragons was assessed based on following spatial parameters; spatial movement, activity areas, habitat use, daily activity patterns, and annual movement. These parameters were used by Fitzgerald, et al. (2002); Ibrahim (2002), Piepgrass and Lang (2000), and Olupot et al. (2001), in assessing spatial ecology in reptiles. Detailed descriptions of each analysis will be included in the relevant chapters.

3.3.1

Spatial Movement and Activity Area

Spatial movement of each size class was determined using data obtained from the radiotelemetry study of hatchlings and juveniles. Spatial movement is defined as a straight line moved between two consecutive points (Samuel & Fuler 1996). This measurement will provide a minimum distance that an animal could have traveled to reach the new location. This technique was also employed by Ibrahim (2002) and Fitzgerald et al. (2002). Spatial movement data will be calculated by means of a computer program ESRI ArcView 3.2 (ESRI 1999) with X Tools and Animal Movement program (Hooge et al. 1999).

In this study, activity area is defined as a particular area covered by an animal in it’s normal activities (Ibrahim 2002). Activity area was calculated using data obtained by means of radiotelemetry (Fitzgerald et al. 2002; and Sastrawan & Ciofi 2002). This study employed methods of Minimum Convex Polygon (MCP) and Adaptive Kernell as the most familiar methods in analyzing activity areas (Fitzgerald et al. 2002; Sastrawan & Ciofi 2002). This analysis employed computer programs of ESRI ArcView 3.2 (ESRI 1999) with X Tools and Animal Movement program (Hooge et al. 1999). Use of GIS methods will provide more accurate relocation mapping and more proportional calculation of activity areas (Kernohan et al. 1998).

27

3.3.2

Habitat Use

To investigate habitat utilization, following parameters used by hatchlings and juveniles were measured; shelter sites and tree preferences. The data were obtained from radiotelemetry study. Locations noted for each radiotracked animal where they occurred were classified as to the habitat type and were converted into the percentages of time each animal spent in a particular habitat type (White & Garrot 1990). To defined the type of habitat in which animal used, habitat type at the adjacent area where animal located was determined subjectively (Jessop et al. 2004)

3.3.3

Long Distance Movement

Long distance movement in Komodo dragons was analyzed using data obtained from the Mark-Recapture study (Husak & Fox 2003; Lancia et al. 1996; & Nietfield et al. 1996). This long distance movement is used to measure the ability of hatchling and juvenile Komodo dragons to move to adjacent valleys or adjacent island. Long distance movement ability was measured as a straight distance moved between two or more consecutive points (Samuel & Fuler 1996) between capture locations from subsequent days and years and were calculated by means of computer program of ESRI ArcView 3.2 (ESRI 1999) with X Tools and Animal Movement program (Hooge et al. 1999).

CHAPTER IV

COMPARISON OF DAILY MOVEMENT PATTERNS, ACTIVITY AREAS, AND HABITAT USE BETWEEN HATCHLING AND JUVENILE KOMODO DRAGONS

4.1

INTRODUCTION

An important aspect of wildlife management programs is the ability to understand spatial requirements and habitat use by animals (Brill et al. 1995; Fitzgerald et al. 2002; Phillips 1995; Piepgras & Lang 2000). The spatial requirement and habitat use are especially important for Komodo dragons inhabiting the Komodo National Park (Burghardt et al. 2002; Sastrawan & Ciofi 2002). Knowledge of inter and intra-island movements is, in fact, essential to understand meta-population dynamics. Several studies have been conducted to describe spatial activities, movement patterns and associated behavior of varanid lizards (e.g. Ibrahim 2002; Thompson 1992; Thompson et al. 2002). In addition, such studies have been conducted to assess interactions between spatial ecology and aspects of their physiology, reproduction and demography (i.e. Christian et al. 1995; Christian & Weavers 1994; James 1996; Phillips 1995). Previous study on Komodo dragons has focused on a preliminary description of movements and activity area size of Komodo dragons using footprint locations and sighting records (Auffenberg 1981). More recently, Sastrawan and Ciofi (2002) detailed the activity areas and movements on five adult Komodo dragons that varies in size between SVL 116 – 154 cm). On varanids, and in squamates generally, there is a distinct lack of knowledge pertaining to the aspects of spatial ecology of early life-history stages, including juveniles, and especially the post-natal or hatchling stage. For many animals, the period immediately following the departure from the natal area can be associated with

29 a period of pronounced dispersal prior to establishment of a more fixed usage of space and eventually establishment of a home range. To date, no study has provided quantitative data on hatchling and juvenile Komodo dragon movement patterns (Sastrawan & Ciofi 2002). To address this knowledge gap, a radio-telemetry study to estimate home range size and describe activity patterns of hatchling and juvenile Komodo dragon was conducted. This study was aimed at addressing three aspects of spatial ecology: (1) Determine dispersal patterns of hatchling following emergence from their nest. (2) Determine movement patterns and activity area size of hatchling and juvenile Komodo dragons, (3) Determine patterns of habitat use by hatchling and juvenile Komodo dragons. These three aspects of spatial ecology represent important facets of the ecology of Komodo dragons as they could provide insight into ontogenic transitions in spatial ecology.

In particular, the dispersal phase is one of the key events

associated with gene flow within or among populations and responsible for maintaining many population processes.

4.2

MATERIALS AND METHODS

4.2.1

Study Site

The study was conducted in the Loh Liang valley on Komodo Island, (8°33’40” S and 119°29’51”E) in Komodo National Park (KNP), East Nusa Tenggara, Indonesia. General descriptions on vegetation cover of KNP are described elsewhere (e.g. Auffenberg 1981; Jessop et al. 2006 unpublished data; Monk et al. 1999). Komodo Island is a rugged, mountainous island covered predominantly by savannah. Deciduous monsoon forest dominated by Tamarind tree (Tamarindus indica).are found in coastal valleys, while closed evergreen forest persists on hills above 500 m.

30 4.2.2

Studied Animals

Five hatchling Komodo dragons with a mean snout to vent length (SVL) of 20.16 ± 0.85 cm (SEM) (range 18.25 – 22.6 cm) and body mass of 0.11 ± 0.01 kg (range 0.095 – 0.135 kg) were captured following emergence from their nest. Hatchlings were captured by hand from fenced nests or using PVC pipe traps (10 cm diameter and 100 cm in length). Seven juvenile Komodo dragons (mean ± SEM of SVL 55.81 ± 2.97 cm and body mass of 3.03 ± 0.56, range 1.4 – 5.7 kg) were captured by hand or in goat meat baited box traps. Trapping methods are described in Chapter III in this thesis. Measurements of individual animals are summarized in Table 4.1.

4.2.3

Radiotelemetry Technique

This study was conducted between March 2004 and June 2005.

In 2004, two

hatchlings and four juveniles were radio-tracked, and in 2005 three hatchlings and four juveniles were followed. Telemetry equipment consisted of activity-sensitive AVM G31V transmitters (AVM Instruments Co. Ltd.), a AVM LA12Q receiver, and a three-element yagi antenna. Each transmitter was attached to the dragon’s base of tail using duct tapes. In 2004, 8 transmitters were attached to four hatchlings and four juveniles and in 2005, 6 transmitters were attached to three offspring and three juveniles. After the transmitters were attached, hatchlings and juveniles were immediately released at the point of captured. Each animal was radio-tracked for 7 – 56 days and comprised a total of 7 – 66 observation events. Each animal was recorded up to four times a day based on latitude and longitude measurement using a Garmin GPS. To increase independency of the data for each radio-tracked animal, individual daily observations were conducted in four sessions; separated by a minimum daily time interval of 2-3 hours (average). Daily observations were made from 0600 to 1800 hrs across 4 time periods of 06 – 09, 09 – 12, 12 – 15, and 15 - 18 hrs. Movement and activity area data were analyzed using 11 - 18 (mean ± SEM: 14.9 ± 0.71) temporally independent fixes over this period.

31 Table 4.1

Summary of SVL, weight and duration of radio-tracking for hatchling and juvenile Komodo dragons.

PIT tag ID Hatchling 64E4218 64CDC09 63DFB2A 64D4C0E 63C1383 Mean ± SEM Juveniles 64CF2AO 639E332 643761C 64E2E95 63DE6F1 63D9C4B 63DB3B7 Mean ± SEM

Year

Weight (kg)

Observations #

22.6 21.3 18.25 18.3 20.35

0.14 0.11 0.1 0.09 0.11

50 26 66 51 67

12 6* 11 18 14

20.16 ± 0.85

0.11 ± 0.01

52.00 ± 16.60

12.2 ± 1.96

61.85 68.35 58.05 55.45 51.15 44.45 51.35 55.81 ± 2.97

3.5 5.7 3.5 3.4 1.65 1.4 2.05 3.03 ± 0.56

18 39 18 14 57 44 7 28.14 ± 7.78

17 17 15 14 16 15 6* 14.29 ± 1.44

SVL (cm)

2004 2004 2005 2005 2005

2004 2004 2004 2004 2005 2005 2005

Positional

* Excluded from movement and activity area calculation due to lack of fixes. Fixes were collected by either direct observation or by triangulation. To calculate triangulation, bearings were taken using a compass from two or more receiving points (Samuel & Fuller 1996; Fitzgerald et al. 2002; Sastrawan & Ciofi 2002). The point at which the bearings crossed denoted the animal’s position. Typically, bearings were obtained within 3 minutes. Receiving points were located between 30-50 meters from the estimated lizard’s position. Level of triangulation reliability within this study was 83.2 ± 3.05 %. Fixes were recorded using a Global Positioning System (GPS; Garmin Etrex), then recorded into an Excel spreadsheet and visualized on to digital maps using ArcView 3.2 (ESRI).

4.2.4

Habitat Assessment

To quantify and compare the habitat use of juvenile and hatchling lizards, habitat and shelter site parameters concurrently with positional data of lizards were collected

32 during radio-tracking (Olupot & Waser 2001). Four parameters were measured and defined as follows; 1) Habitat strata Use of either terrestrial or arboreal strata 2) Habitat type The presence of lizards in one of three key habitat types: open deciduous forest, closed dense forest, and savannah grassland. These habitat types were readily distinguished by canopy closure and floristic composition. 3) Shelter site Included a description of resting or sleeping location based on the use of vegetation (identified to species), or substrate type. Further, with relation to vegetation, particularly trees, the tree diameter at breast-height (Dbh) and tree height were also recorded.

Tree Dbh was obtained by measuring the tree

circumference at breast-height and calculated using the formula circumference = 2πr (where: π = 3.14, 2r = diameter). Tree height and Komodo dragons’ position above ground was calculated using a Suunto Clinometer PM5 (Suunto, Finland). 4) Elevation Ground elevation at which a lizard was located was recorded alongside every fix locations.

4.2.5

Data Analysis

A)

Movement and Orientation

Directionality and tortuousity were analyzed to describe the pattern of path movement (linearity) of Komodo dragons (Nams & Bourgeois 2004). Directionality was analyzed by measuring the turning angle of movement on each point in a compass direction (Claussen et al. 1997). The turning angles indicate the movement angles between two consecutive points (Higham et al. 2001). Tortuosity was measured by

33 analyzing the fractal dimension (D) (Milne 1991), whose values range between 1-2: D = 1 the animals’ path of movement is straight; D = 2 (i.e. maximum) the animals path of movement is so tortuous as to completely cover a plane (Nams & Bourgeois 2004). To describe site fidelity, Site Fidelity Test was ran with 1000 replications to obtain the r2 value, the lower r2 value, the highest fidelity of the animal (Hooge & Eichenlaub 1997). Directionality and Site Fidelity were computed using the Animal Movement Program extension (Hooge et al. 1999) and X Tools of ArcVIew 3.2 (ESRI) while Fractal dimensions were computed using the computer program Fractal (Nams 2004a). Komodo dragon movement distances were calculated as the distance moved between two consecutive points (Samuel & Fuler 1996). This measurement estimates the minimum distance that an animal would have traveled between two locations. Mean daily movement distance was obtained by dividing the total distance of recorded movements by the total number of radio-tracking days. A similar method has been applied elsewhere in investigating reptile movements. (e.g. Ibrahim 2002; Fitzgerald et al. 2002; Whitaker & Shine 2003; Phillips 1995). These calculations were made using the Animal Movement Program (Hooge et al., 1999) and X Tools extension of ArcView 3.2 (ESRI). B)

Activity area

In this study, the activity area was defined as the area occupied by an animal during the study period. Core area was defined as the area in which studied animal mostly visited or occupied during the study period. Activity areas were calculated using three methods: the 100% Minimum Convex Polygon (MCP), 95% and 50% Adaptive Kernell Analysis (AK). MCP is the most common and simplest method used to estimate the activity area of animals by calculating the smallest possible convex polygon around the outermost animal locations (Kenward 1993; Samuel & Fuller 1996). Sastrawan & Ciofi (2002) applied MCP to measure adult Komodo dragon’s activity area size. However, MCP only uses a proportion of location data; it is sensitive to outliers and incorporates large areas that may have never been used by the animal (Melville & Swain 1999; White & Garrot 1990). The 95% AK is also suitable

34 to use in estimating activity areas of animals by calculating the distribution of 95% of the total fixes (Kernohan et al. 1996) by smoothing the location data (Kernohan et al. 1998). The 95% AK is believed to be a very effective method for estimating activity area (Katajisto & Moilanen 2005 in press; Pavey et al. 2003). The 50% AK method was used to determine core areas within the activity area of hatchling and juvenile Komodo dragons. The 50% AK has been widely used to determine the core area or habitat use in other reptiles (Whitaker & Shine 2003; Fitzgerald et al. 2002; Kernohan et al. 1998; Piepgras & Lang 2000; Smith et al. 1999). Overlaps were estimated by calculating the size of overlapped activity areas between individuals and compared to the total of activity area (Figure 4.3). To increase the quality of data, radio-tracking animals with less than 10 fixes (data for hatchling 64CDC09 and juvenile 6eDB3B7) were excluded. Daily movements and activity areas were analyzed based on data subset of four hatchlings and six juveniles with minimum 11 fixes. Activity area estimations were calculated using the Animal Movement Program (Hooge et al. 1999) and X Tools extension of ArcVIew 3.2 (ESRI). A similar technique for studying spatial ecology was applied by King and Gurnell (2004) and Piepgras and Lang (2000). C)

Habitat Use

Patterns in habitat use were analyzed by comparing the frequency of particular habitat types (arboreal and terrestrial), types of vegetation (closed forest, open forest, and savanna), elevation of location, shelter sites, tree species, tree DBH and tree height, and animal position above ground. To determine if Komodo dragons were using their habitat in a non-random fashion, their observed use of habitat was compared with a random selection of locations calculated using the program Ecological Methodology V. 6.1 (Krebs 1999; 2002) to generate 100 random latitude and longitudes positions within Loh Liang. These random locations were then assigned their habitat type and elevation drawn from digital topographic maps.

35 D)

Statistical Analysis

Prior to analysis all data was log transformed (Sutherland et al. 2000) to meet the assumptions of parametric tests (Zar 1999). Log transformed data that did not meet the assumptions was statistically analyzed using a nonparametric statistical procedures. All data is presented in tables and graphs of the means and standard error of the mean (SEM) of back-log transformed data. T-test, Chi square test and MannWhitney U tests were used to determine the in habitat types used (King & Gurnell 2005; Rheaney & Whiting 2003). Linear regression test and ANOVA was used to test differences in time spent on a tree between hatchlings and juveniles. For all statistical tests, significance was inferred at P < 0.05.

4.3

RESULTS

4.3.1 Patterns of movement During the study, hatchlings dispersed in a predominantly linear fashion with little movement over previously occupied areas (Figure 4.1). In contrast, juvenile dragons exhibited more tortuous movement paths reflecting increased movement over the same area (i.e. use of an activity area) (Figure 4.2). Fractal analysis indicated that the linearity of the movement paths undertaken by hatchlings D = 1.11 ± 0.01 was significantly more directed (i.e. strait) than that of juvenile dragons (D = 1.39 ± 0.05; Mann-Whitney U test; Z = -2.558, p = 0.01). The degree of site fidelity in hatchlings (r2 = 729502.69) was significantly lower than that in juveniles (r2 = 2729220.96; Ttest t1,9=-39.123.01, p < 0.001). Based on two estimates of daily movements, hatchlings were significantly less active than juvenile dragons and on average moved 32.62 ± 12.67 m/day compared to 129.137 ± 41.71 m/day (T-test t1,9 = -3.014, p = 0.015) (Table 4.2). Consistent with this the longest daily movements recorded by hatchling (163.99 ± 22.96 m/day) were significantly less than that of juvenile dragons (509.87 ± 73.32) (T-test t1,9 = -5.241, p < 0.001). Daily activity of hatchlings was significantly less than juvenile dragons

36 (Chi square test; x2 = 51.68, p < 0.001) based on an activity index calculated using the relative proportion of movement fixes compared to the proportion of stationary fixes. Tabel 4.2

Detail of results on radio-tracking study of hatchling and juvenile Komodo dragons. Maximum Overnight

Total Move (m)

Daily Move (m)

64E4218

4

983.4

70.24

191.19

4.83

20.12

4.74

63DFB2A

15

571.61

15.04

195.08

1.72

13.06

3.61

64D4C0E

4

692.91

23.1

96.63

1.96

13.48

2.51

63C1383

15

949.38

22.08

173.08

3.59

12.143

2.71

Mean Juveniles

9.5 ± 3.17

799.32 ± 99.82

32.61 ± 12.67

163.99 ± 22.96

3.02 ± 0.73

14.7 ± 1.83

3.39 ± 0.51

64CF2AO

6

2286.24

326.61

397.87

12.53

33.23

10.48

639E332

2

6308.96

143.38

791.59

32.37

16.34

2.33

643761C

2

350.72

43.84

334.35

4.02

5.49

0.56

64E2E95

5

2879.15

89.97

427.54

17.42

32.55

2.45

63DE6F1

2

5556.63

99.23

672.06

61.77

30.52

4.3

63D9C4B

2

3445.54

71.78

435.83

17.76

21.57

2.65

3.17 ± 0.75

3471.21 ± 892.46

129.14 ± 41.71

509.87 ± 73.32

24.31 ± 8.38

23.28 ± 4.49

3.79 ± 1.42

5.7 ± 5.1

2402.45 ± 676.16

90.53 ± 92.18

371.52 ± 71.08

15.8 ± 5.97

19.85 ± 3.02

3.63 ± 0.84

PIT tag

Longest move (m)

100% MCP (ha)

95% AK (ha)

50% AK (ha)

Hatchlings

Mean OVERALL Mean

Table 4.3

Percentages of overlap on activity area in juveniles

VK ID

MCP (ha)

OVERLAP (ha)

OVERLAP (% )

64CF2A0

12.53

2.55

20.34

OVERLAPPED VK ID 639E332

639E332

32.37

2.55

7.88

64CF2A0

643761C

4.02

3.66

91.01

64E2E95

64E2E95

17.42

6.65

38.20

63DE6F1

61.77

2.99

4.84

643761C / 63DE6F1 63DE6F1

37

#a

8ｰ33'55"

8ｰ33'05"

Latitude (South)

8ｰ34'00"

#c

#b

8ｰ34'05"

#d 8ｰ33'10" 8ｰ34'10"

8ｰ34'15" N

N

0

50

100 Meters

0

8ｰ33'15" 119ｰ29'45"

119ｰ29'50"

119ｰ29'55"

119ｰ30'00"

8ｰ34'20"

119ｰ29'50"

100

119ｰ29'55"

200 Meters

119ｰ30'00"

119ｰ30'05"

Longitude (East) Figure 4.1

Movement patterns of hatchling Komodo dragons. Arrows indicate starting point and general direction of movements. Letter refers to hatchlings ID as follow; a) 64D4C0E, b) 63DFB2A, c) 64E4218, d) 63C1383.

Latitude (South)

38

a

b

8ｰ33'10"

8ｰ33'50"

8ｰ33'15"

8ｰ33'55"

8ｰ33'20"

8ｰ34'00"

8ｰ33'25"

8ｰ34'05"

8ｰ33'30"

8ｰ34'10"

8ｰ34'15"

8ｰ33'35" N

N

0

8ｰ33'40"

100

200 Meters

0

100

200 Meters

8ｰ34'20"

119ｰ30'20"

119ｰ30'25"

119ｰ30'30"

119ｰ30'35"

119ｰ30'40"

119ｰ30'45"

119ｰ29'40"

119ｰ29'45"

119ｰ29'50"

119ｰ29'55"

119ｰ30'00"

Longitude (East) Figure 4.2

Movement patterns of two juvenile Komodo dragons (a: 639E332, b: 63D9C4B). Circles indicate shelter sites.

39

a

b

8ｰ32'45"

8ｰ32'45" #3

#4

#3

#5

#

8ｰ33'00"

8ｰ33'00"

#1 #5

#1

#4

8ｰ33'15"

8ｰ33'15"

#2

Latitude (South)

#2 8ｰ33'30"

8ｰ33'30" #5

8ｰ33'45"

8ｰ33'45" #6

8ｰ34'00"

8ｰ34'00" #6

8ｰ34'15"

8ｰ34'15"

N

N 0

500

500

1000 Meters

8ｰ34'30"

8ｰ34'30" 119ｰ29'30"

Figure 4.3

0

1000 Meters

119ｰ29'45"

119ｰ30'00" 119ｰ30'15" 119ｰ30'30"

a 119ｰ30'45"

b 119ｰ29'30" 119ｰ29'45" 119ｰ30'00" 119ｰ30'15" 119ｰ30'30" 119ｰ30'45"

Longitude (East)

Activity area overlaps of six juvenile Komodo dragons as calculated by MCP (a) and 50% Adaptive Kernell (b). Numbers refer to juvenile ID as follow: 1) 64CF2A0, 2) 639E332, 3) 64E761C, 4) 64E2E95, 5) 63DE6F1, 6) 63D9C4.

40 4.3.2 Size of Activity Areas Activity areas of hatchlings and juveniles ranged between 1.72 – 4.83 ha and 4.02 – 61.77 ha for MCP; 12.14 - 20.12 ha and 5.49 – 33.23 for 95% AK; and 2.51 – 4.74 and 0.56 – 10.48 ha for 50% AK (Table 4.2, Figure 4.3). Hatchlings used significantly smaller activity areas, of approximately 8 times less than juveniles for the 100% MCP (T-test; t1,9 = -3.66, p = 0.001). However, there was no significant differences in 95% AK (T-test t1,9 = -0.02, p = 0.18) and neither for 50% AK (T-test t1,9 = 0.396, p = 0.70). In five of six cases, the activity areas of juvenile dragons overlapped with one (n = 4) or two (n = 1) conspecifics. The extent of overlap of activity areas ranged from 4.84 – 91.01 % or 2.55-6.65 ha (Table 4.4; Figure 4.3.a).

4.3.3 Patterns in Habitat Use There was a significant difference between hatchlings and juveniles in several measured parameters of habitat use. All radio-tracked hatchlings were almost entirely arboreal (97.7%) compared to juveniles which more terrestrial (71.0%) (Chi square test; x2 = 239.22, p < 0.001) during the course of observation (Figure 4.4a). Hatchlings were remained on the same tree ranged from 4 to 15 days (mean 9.5 ± 3.17 days) before moving to the next tree (Table 4.2). Hatchlings were rarely observed on the ground, except during long distance movements between trees (> 30 m). There was an occasional arboreal movement whereby hatchlings were able to move between trees with overlapping canopy. In contrast, juveniles were significantly more terrestrial than arboreal (Figure 4.4a). However, they were still often encountered in trees. Juveniles, on the other hand, spent significantly less time on trees ranged from 2 to 6 days, (mean 3.17 ± 0.75; T-test t1,8=2.257, p = 0.038) (Table 4.2). However, body size, rather than age class was a better indicator of habitat use, as there was a highly significant negative linear relationship between body size and amount of arboreal activity (% Arboreal activity = -2.070 * SVL + 139.244, r = 0.965; ANOVA, F1,9 = 108.423, p < 0.001) (Figure 4.4b).

41

120 255

100

Frequency of Use (%)

a 80 Hatchling Juvenile

130

60

40 53

20 6

0 Terrestrial

Arboreal

Habitat Strata

Frequency of arboreal activity (%)

120 b

100 80 60 40 20 0

10

20

30

40

50

60

70

80

SVL cm

80

42

73

Frequency of Use (%)

c

60

Hatchling Juvenile

40

20

16 7

6 5 0 Closed Forest

Open Forest

Savanna

Habitat Type

Figure 4.4

Differences in terrestrial and arboreal habitat use by hatchling and juvenile Komodo dragons (a). Figure b depicts the relationship between body size (SVL) and arboreal activity in the radio tracked Komodo dragons.

42 With respect to habitat preferences, both hatchlings (Chi square test; x2 = 45.86, p < 0.001) and juveniles (Chi square test; x2 = 85.04, p < 0.001) were observed significantly more frequently in open deciduous forest, compared to either closed dense forest or savannah (Figure 4.4.c). There was no significant difference in the frequency of observed habitat preference use between hatchlings and juveniles (Chi square test; x2 = 1.891, p = 0.389; Figure 4.4c.). For both hatchlings (Chi square test; x2 = 14.206, p < 0.001) and juveniles (Chi square test; x2 = 16.205, p < 0.001) their habitat use preference was significantly different to that calculated for habitat types from randomly generated locations across the study sites. With respect to elevation there was a significant preference for hatchlings to be located in the lowest elevation class (54.54 % for < 25 m above sea level; Chi square test; x2 = 20.98, p < 0.001) (Table 4.4). Juvenile dragons (Chi square test; x2 = 9.26, p = 0.002) exhibited a significant preference for elevations between 25 – 50 m (36.17 %) above sea level (Table 4.4). These elevation preferences for hatchlings and juvenile dragons were significantly different (Chi square test; x2 = 25.127, p < 0.001). Further, both hatchlings (Chi square test; x2 = 53.707, p < 0.001) and Juveniles (Chi square test; x2 = 29.736, p < 0.001) elevations preferences differed significantly from random selection of elevations within their environment.

4.3.4

Shelter Sites Selection

Shelter sites were defined as those places used by hatchlings and juveniles for resting (also as sites between movements - for juveniles only) or as overnight refuges. Hatchlings used trees exclusively for shelter. They significantly used live (84.71 %) over dead trees (15.29 %; Chi square test; x2 = 122.859, p < 0.001) (Table 4.4). Amongst live trees (15 species recorded), there was a significant tendency for hatchlings to occupy Tamarindus indica tree (45.37 %) (Chi square test; x2 = 122.86, p < 0.001) (Table 4.5). Juveniles used predominantly crevices under or among rocks (51.77 %) as shelters. These shelters could be a part of a larger forested area with significant granitic exfoliation forming rocky fields or a clump of rocks associated

43 with trees. Trees (9 species recorded) were occasionally used by juveniles as locations for resting or basking (Table 4.5). With respect to arboreal habitat use, hatchlings used significantly thinner (tree DBH; T-test t1,10 = -2.634, p = 0.025) and shorter trees (T-test t1,4 = -2.915, p = 0.043) than juveniles (Table 4.6). However, there was no significant difference in tree elevation use between hatchlings and juveniles (T-test t1,4 = 2.23, p = 0.089). Table 4.4 Frequency of elevation preferred by hatchlings and juveniles (%) Elevation (m)

Hatchlings

Juveniles

< 25

54.54

24.47

25 – 50

40.00

36.17

50 – 75

5.45

14.89

75 – 100

0.00

21.28

>100

0.00

3.19

Table 4.5 Major tree preferences used by hatchlings and juveniles (%). Tree species

Hatchlings Juveniles

Tamarindus indica

44.61

70.93

Corypha utan

14.21

0.00

Saruga sp

4.73

1.67

Schleichera oleiosa

7.20

2.40

Dead/log

13.19

0.00

Other

16.06

25.00

Table 4.6 Total number of tree species, and mean values of tree parameters used, and animal position on tree. Parameters # Tree sp.

Hatchling

Juvenile 15

9

Tree DBH (cm)

43.22 ± 7.14

66.58 ± 5.42

Tree height (m)

12.51 ± 0.72

16.14 ± 1.01

VK height (m)

7.89 ± 0.85

5.47 ± 0.67

44 4.4

DISCUSSION

Hatchlings displayed several key differences with respect to their spatial ecology compared to juvenile Komodo dragons. In particular, their post-natal movements were essentially linear compared to those of juveniles that appeared to have already developed a defined area of established activity. This predominantly linear movement could possibly underpin a deliberate type of dispersal behavior that enables hatchlings to move as far as possible away from their nesting sites relative to the actual distance traveled. Based on the limited number of hatchlings radio-tracked, there was no indication that hatchlings were heading towards a consistent bearing similar to natal dispersal in other reptiles including hatchling Green sea turtles (Chelonia mydas) that display well-oriented post-emergence dispersal (Salmon & Wyneken 1987). Rather, the movement of hatchling dragons was similar to patterns of natal dispersal demonstrated by hatchlings of Blanding turtles (Emydoidea blandigii) (McNeil et al. 2000) and the Australian freshwater crocodile (Crocodylus johnstoni) (Tucker et al. 1997). Pough et al. (2001) described that lizard hatchlings moved out of their natal areas to find a suitable patches of habitat which are not already occupied by larger conspecifics or to avoid cannibalism by adults. As reported by Sarno et al. (2003), dispersal in juvenile Guanacos occurred in order to avoid conflict with adults. Cannibalism among Komodo dragons has been observed (Auffenberg 1981) as well as in other Varanids such as V. griseus, V. gouldii and V. gigantheus (King & Green 1999). This early life-stage is dominated by high mortality because hatchlings are particularly vulnerable to predation (Mattison 1992). Dispersal in threatened species is important for populations to enlarge their distribution and to maintain genetic variability as this is a critical component of population dynamics (Lebreton et al. 2003; Sutherland 2000; Trakhtenbrot et al. 2005). In reptiles, dispersal in hatchlings is correlated with rates of adult presence (Pough et al. 2001). Sutherland et al. (2000) reported that natal dispersal was positively correlated with body mass, where larger animals have larger dispersal distance.

45 From the data, hatchlings displayed a consistent pattern in habitat use. They were arboreal during their first stage of life. Following emergence, hatchlings immediately climbed the nearest tree (Auffenberg 1981). Their arboreal nature is presumably a strategy for avoiding their terrestrial based larger conspecifics and possibly aerial predators such as birds of prey (Auffenberg 1981; King & Green 1999). Thompson (1993) reported similar behaviour in V. caudolineatus. Hatchlings of Blanding’s turtles hide in vegetation soon after emergence (McNeil et al. 2000). Arboreal habits could provide advantages for hatchlings to test differences in escaping tactics from predators (Higham et al. 2001). Arboreal habitat also provides resources such as food and shelter (Reaney & Whiting 2003). Hatchlings were observed to feed on Gecko gecko (PIT tag ID 64E4218 and 64D4C0E) which are commonly on trees in Komodo island (Auffenberg 1980). Unfortunately, this study could not determine how long the hatchlings spent their life as being arboreal. Observations from KNP rangers suggest that hatchlings could lead an arboreal life for up to five years. Even thought juveniles were terrestrial, three out of six juveniles (SVL < 60 cm) were found occasionally on trees for overnight shelter. Auffenberg (1981) reported a similar arboreal characteristic on juveniles less than 70 cm in SVL. Arboreality in juvenile of other terrestrial Varanid species were also reported in V. doreamus (Bohme et al. 2004) and V. salvator (Gaulke & Horn 2004). The rate and distance moved by hatchlings within their natal valley was relatively slow and small compared to juveniles, suggesting that this early dispersal phase was not particularly important for the overall pattern of dispersal from natal sites. Movements in hatchlings were shorter than in juveniles. Mean juvenile daily movement was four times larger than that of hatchlings, but six times smaller than adults (Sastrawan & Ciofi 2002). As reported by Perry and Garland (2001), terrestrial lizards have larger movement and activity area size than arboreal individuals. In contrast, Pough et al (2001) noted that arboreal reptiles have a low movement pattern. King and Green (1999) noted that arboreal monitors such as V candolineatus and V. brevicauda showed a similar characteristics to Komodo dragons.

46 Movement in juvenile reptiles increase with age (McMaster & Herman 2000). The study indicated that the larger the animal, the larger the daily movement and the longer the movement. Sastrawan and Ciofi (2002) reported similarity in adult male and adult female Komodo dragons. Similar patterns in other species reptiles were also reported, such as in arboreal snakes (Fitzgerald et.al 2002; Pearson et al. 2005). Many authors defined activity areas as a portion of a particular area used during a defined period of time and will expand as over an extended period of time (King & Green 1999; Thompson et al. 2002). There was size variation in activity areas between hatchlings and juveniles. Juvenile mean activity areas were eight times larger than those of hatchlings were. This study also suggested that juveniles were able to explore and expand their foraging areas better than hatchlings, which had to familiarize with their new environment after emergence. Activity area size increased as Komodo dragons grew older. Average adult activity area is 19 times larger than in juveniles (see also Auffenberg 1981; Sastrawan & Ciofi 2002). Smith et al. (1999) reported that the adult Angonoka turtle Geochelone yniphora has a larger activity area size compared to juveniles. According to Pough et al. (2001) many authors reported a positive correlation between activity area size and body size in many species of reptiles. Christian and Waldschmidt (1984) demonstrated that the lizard’s body size and sex were significantly correlated to size of activity area. Perry and Garland (2002) also demonstrated that activity area is correlated with body size in different species of lizards. According to this study, both hatchlings and juveniles had small core activity areas. Komodo dragons used core areas as shelter sites rather than for foraging. Small core area sizes were also reported for the Massasauga (Johnson 2000). In hatchling Komodo dragons, the small size of the core area was probably due to less active behavior in this age class as far as exploration of their new environment concerned. Yet, juveniles preferred particular spots suitable to their needs. Although juveniles moved away from their overnight shelter, they returned to their shelter in the afternoon. Nevertheless, some juveniles remained at the same overnight shelter for a

47 few days (e.g. 639E332, and 63D9C4B). However, many authors reported that there is a significant correlation between age or sex class, activity and core area in other reptile species, such as snakes and turtles (e.g. Melville & Swain 1999; Piepgrass & Lang 2000; Whitaker & Shine 2003). King and Green (1999) suggested that core activity areas varied seasonally. In this study, however, it was not possible to investigate seasonal movements and seasonal activity areas. The importance of dispersal area for hatchlings is determined by the use of specific tree species during their early natal dispersal. For juveniles, the importance of their foraging area is highlighted by the 100% MCP overlap. These overlapping activity areas indicated that these areas provided sufficient resources that are probably shared by neighboring juveniles. Even thought there were some overlaps in activity areas among juveniles, there was no evidence of territoriality. Juveniles were solitary as none were found on the same tree at one time. As discussed previously in this chapter, it was shown that hatchlings remained arboreal during the first stage of their life. Most hatchling activities were carried out on a tree rather than on the ground. Hatchlings descended to the ground only to move to another tree even when tree canopy could provide a pathway for travel. Auffenberg (1981) noted that hatchling Komodo dragons were able to take a leap from branch to branch. During this study, two hatchlings (64D4C0E and 63DFB2A) were observed to move between trees using aerial paths, when canopies connected to each other. Fitzgerald et al. (2002) reported arboreal snakes to move preferentially on the ground. According to the author, canopy structure (especially physical connectivity between branches of adjacent trees) was not an important constraint to movement patterns. Both hatchlings and juveniles used trees as shelter. However, hatchlings showed a wider selection of tree species for sheltering than did juveniles (15 versus 9 tree species). A similar pattern was described for an arboreal phyton Morelia spilota in Australia (Pearson et al. 2005). Radio-telemetry suggested that juvenile Komodo dragons preferred to stay on bigger and higher trees than those chosen by hatchlings. This probably indicated that juveniles selected particular sites in relation to their body

48 size. Auffenberg (1981) described that since vegetation could limit the vision of adult Komodo dragons, it was important for small Komodo dragons to hide from the adults. Besides using the Tamarind tree, hatchlings were often found hiding on the Gebang tree (Corypa utan). Live Gebang trees contain dead branches at the base of their trunks that provide cover for hatchlings to hide, while dead Gebang tree provide holes at relatively high elevations above that ground. Blazquez and Rodriguez-Estrella (2001) in their study of Spiny-tailed iguanas, Ctenosaura hemilopha, reported that selected trees could allow hatchlings and juveniles to take shelter, to feed, basking in the morning, and minimize the risk of predation. In their early life stage, Komodo dragon showed their tendency to discover their new environments in order to find suitable and safest space from predators. Exploration was demonstrated by the increasing in size of movement and activity areas along with their age. McMaster and Herman (2000) documented that along with increasing of age, movement in juvenile reptiles become larger. Greenwood and Swingland (1984) noted that animals are out of their natal sites to exploit available resources. Immature Komodo dragons demonstrated their requirements of hidden places to avoid conflict with their conspecific or other predators, including adults, as noted by Mattison (1992) that mortality in lizards is highest during the early phase of their life because they are more vulnerable to predation. Further, long-term and comprehensive studies are important to investigate detail patterns in spatial use during early life stage of Komodo dragons.

CHAPTER V

ASSESSING LONG DISTANCE MOVEMENT OF HATCHLING AND JUVENILE KOMODO DRAGONS

5.1

INTRODUCTION

Movement of individuals through their habitat is a key process underpinning many population processes and in particular gene flow. Movements underpinning gene flow are typically classified as dispersal (Bohonak 1999). Dispersal is one of the most essential fitness events in the lives of most individual animals and in turn for important processes affecting the ecology and evolution of populations and of the most important part of conservation studies of endangered animal (Greenwood 1978; 1980; Koenig et al. 1996). There are three critical mechanisms for dispersal: (1) leaving the natal site (natal dispersal), (2) dispersing in terms of accession to breeding site (breeding dispersal), and (3) settling into a new home range (immigration) (Lebreton et al. 2003). Natal dispersal is the movement of individuals from their place of birth to their first breeding location (Greenwood 1980). According to Pough et al. (2001) hatchling reptiles move out of their natal areas to find suitable patches of habitat that are not already occupied by larger conspecifics. This allows access to specific resources and avoids cannibalism by adults. Greenwood (1980) also defined breeding dispersal as the movement of individuals between successive breeding sites, either within a breeding season or between breeding seasons. Bancroft and Smith (2005) demonstrated how movement into a new home range was correlated with a specific dispersal mechanism.

50 Dispersal is an essential key process that affects extended population structure, dynamics and gene flow (Blouin-Demers & Weatherhead 2002; Bowman et al. 2002; Bullock 2002; Hanski 1999). In term of metapopulation dynamics, movement among sub-populations is a key factor to survival, recruitment, emigration and immigration in sub-populations (Drake & Alisauskas 2004). Dispersal is also important for the evolutionary processes of the species (Lenormand 2002). Dispersal can also play an important role in the behavior and social systems of animals (Wolff 1999). Caro (1994) and Gompper (1996) suggested that dispersal could also contribute to increased foraging success and thus decreased competition among males. Female breeding dispersal is related to mate choice in order to improve mate quality and locate resources that facilitate offspring fitness (Otter & Ratcliffe 1996). Moving animals may contribute new genes to populations. Gene flow is strictly affected by movements of genes within or between populations (Ciofi 2002). Lenormand (2002) described that movement affects patterns in gene flow and the divergence of alleles. Movement of adult Black Rat Snakes was suggested as contribution to the out-breeding mechanism (Blouin-Demers & Weatherhead 2002). Drake and Alisauskus (2004) reported dispersal could contribute to the gene flow among sub-populations. Gompper et al. (1998) demonstrated that dispersal could influence genetic relationships amongst individuals of a social carnivore. Storz (2005) reported that trait diversification in great tits reflects the effects of dispersal and spatial selection. The absence of gene flow, on the other hand, increases inbreeding and genetic drift and, in small populations, the probability of extinction (Konuma et al. 2000; Madsen et al. 1996). Low genetic variability is generally correlated with inbreeding. Rosenfield and Bielefeld (1992) reported a relationship between low natal dispersal and high inbreeding incidence in Cooper’s hawk. Inbreeding can cause severe low fitness for small populations (Lande 1998).

51 Site fidelity is often characterized by events of philopatry (Reed & Oring 1993). Variability in site fidelity is influenced by habitat, resource distribution and includes mating and parental care systems (Emlen & Oring 1977; Powell 1989). The interaction of movement patterns and landscape features affects individual space-use, population dynamics and dispersion, gene flow, and the redistribution of nutrients and other materials (Johnson et al. 1992). To date, there has been no detailed study on the dispersal capacity of Komodo dragon (Auffenberg & Auffenberg 2002; Sastrawan & Ciofi 2002). The objective of this study is to investigate the dispersal capacity in immature Komodo Dragons (i.e. hatchlings and juveniles). Sutherland et al. (2000) suggested that movement from the natal site in the early life stage of an animal is important to the processes of demography, population dispersion, colonization, and gene flow. As parental care is rare on reptiles, it is suggested that post-natal or early life-phase dispersal should be common (Olson & Shine 2003; Shine 1988). This study aimed at measuring the movement capacity of hatchling and juvenile Komodo dragons at two different spatial scales that are thought to contribute to gene flow among; 1)

Movement between adjacent valleys within islands

2)

Movement between adjacent islands.

5.2

MATERIALS AND METHODS

5.2.1 Study Sites and Capture Technique The study was conducted over 10 sites across four islands in Komodo National Park. These four islands encompass the extant distribution of this species within Komodo National Park and include populations from Komodo (393.4 km2), Rinca (278.0 km2), Gili Motang (10.3 km2) and Nusa Kode (referred to as Gili Dasami) (9.6 km2). Study site description and area size of selected study sites and mark-recapture techniques were described in Chapter III.

52 Dispersal in animal can be measured using the dispersal rate (number of dispersers leaving their natal territory) and the expected distance moved by each disperser (Sutherland et al. 2000). The extent of gene flow between populations can be measured by means of movement data as a direct method or indirectly method in by using genetic markers (Blouin-Demers & Weatherhead 2002). Direct assessment of movements among populations is a valid approach for the interpretation of gene flow in the ecological context (Bohonak 1999; 2002; Bossart & Prowel 1998). Mark recapture is the most effective way to measure population parameters (Seber 1982). This method is also useful to obtain data on movement and population dynamics in animals (Claussen et al. 1997; Lancia et al. 1996; Lebreton et al. 2003; White & Clark 1996). Several authors have used mark recapture to measure movement in animals (e.g. Clobert et al. 2000; Limpus & Walter 1980; Magnusson 1979). A limitation of this method is that movements within and among populations vary in space and time (Schwartz & Arnason 1996) and detailed information on animal movement, such as frequency of movement, cannot be assessed. In practical, mark recapture methods require individual marking (Lancia et al. 1996). Koenig et al (1992) suggested that tagging using passive integrated transponders (PITs) is the most efficient method in mark recapture studies to investigate dispersal mechanism. During the study period a total of 149 hatchlings and 304 juveniles were captured and tagged (Table 5.1). Within three years of study, 1 hatchling and 76 juveniles were recaptured in the subsequent years. To increase the sample size for hatchlings, data on 1 recaptured hatchling from March 2006 was added. These recapture data were then analyzed for distance of movements (see below).

Table 5.1 Total number of tagged animals for each year. Year

Hatchling Juvenile

2003

51

131

2004

6

87

2005

92

86

Total

149

304

53 5.2.2

Data Analysis

Measures of dispersal capacity of hatchling and juvenile Komodo dragons were obtained by analyzing daily, annual, farthest daily, and farthest annual movements of animal. Daily movement (distance travelled by animal in a day) was calculated from Within Trip Recapture / Resight (WTR) data which was taken during the trapping session in one location. Annual movement (mean annual distance travelled by animal) was calculated as the mean of distance between the consecutive annual capture positions during the mark-recapture period (2003-2005). Farthest daily and farthest annual movement was calculated as the distance between the first locations of captured with the farthest location of recaptured. To measure the influence of terrestrial barriers on movement, geographical barriers were identified and scored depending on their potential effect on animal movement. Several measurements were taken on map of the Komodo National Park (BAKOSURTANAL 2000) as follow; elevation of the nearest highest peak elevation to the edge of the valley (h), distance to the nearest highest peak from edge of the valley (d), and degree of slope (s). Edge of the valley was depicted virtually by creating a poly-line along the elevation contour lines of 62.5 m on the map. Random points were placed along the virtual edge line using the Ecological Methodology computer program (Krebs 2002; see Krebs 1999). The number of points is a result of the total length of the virtual edge line (km) divided by 1 km (for example, total length of virtual edge line for Loh Sebita was 20.1 km, giving a total of 20 random points). Three random bearings between 0-180° were picked from each random point to measure each parameter of the barrier mentioned above. Along the bearing line, the nearest highest peak (h) and the distance (d) to the virtual edge line was taken. Degree of slope (s) was ranked between 1 – 10, which was calculated by dividing the highest peak elevation by the distance to the highest peak and multiplied by α , where

α value is 10 (Equation 5.1). Vegetation type was scored as 1 (closed forest), 2 (open forest), and 3 (savannah). Area size was calculated as the size of the valley by creating polygon along the elevation contour lines of 2.5 m and coastal line (0 m) on the map.

54

s=

h ×α d

(Equation 5.1)

To measure influence of marine barriers distance between islands was measured. Similar technique as employed to measure terrestrial barrier was employed also to measure marine barriers. A number of random points were placed along coastal line (0 m) on topographical map of the Komodo National Park (BAKOSURTANAL 2000). To obtain the number of random points, the total length of coastal line (island boundary) divided by 10 km. From each random point distance to the nearest adjacent island was measured. All distance of movements and barriers scaling were calculated using Animal Movement program (Hooge et al. 1999) and X Tools extension of Arc View 3.2. (ESRI).

5.2.3

Statistical Analysis

Prior to analysis all data were log transformed (Sutherland et al. 2000) to meet the assumption of parametric tests (Zar 1999). Log transformed data that did not meet the assumptions was statistically analyzed using nonparametric statistical procedures. All data is presented in tables and graphs of the means and standard error of the mean (SEM) of back-log transformed data. The Chi square test was used to determine differences among slope degree between valleys (King & Gurnell 2005; Rheaney & Whiting 2003).

Paired T-tests was used to determine differences in distance of

movement between WTR data and annual mark recapture data. Pearson correlation test was used to determine relationship between distances of movement with the size of the valley. For all statistical tests, significance was inferred at P < 0.05.

< 1 0 1 00 02 0 2 00 03 0 3 00 04 0 4 00 05 0 5 00 06 0 6 00 07 0 7 00 08 0 8 00 0 90 -9 0 0- 0 1 0 10 0 0 00 1 1 - 11 0 0 00 1 2 - 12 0 0 00 1 3 - 13 0 0 00 1 4 - 14 0 0 00 -1 50 >1 0 50 0

Frequency (%) < 10 10 0 020 200 030 300 040 400 050 500 060 600 070 700 080 800 090 90 0 0 10 -10 00 00 11 -11 00 00 12 -12 00 00 13 -13 00 00 14 -14 00 00 -1 50 >1 0 50 0

Frequency (%) < 10 10 0 020 200 030 300 040 400 050 500 060 600 070 700 080 800 0 90 -90 0- 0 10 10 00 00 1 1 -1 1 00 0 0 1 2 -1 2 00 0 0 1 3 -1 3 00 0 0 1 4 -1 4 00 0 0 -1 50 >1 0 50 0

Frequency (%)

55

60

25

25

Figure 5.1 a

50

40

30

20

10

0

Distance (m)

b

20

15

10

5

0

Distance (m)

c

20

15

10

5

0

Distance (m)

Frequency of annual movement for hatchling (a), daily and annual movement for juvenile (b, c).

56 5.3

RESULTS

The study showed a low number of recapture events for hatchlings. From the total of 149 tagged hatchlings only two hatchlings were recaptured. One hatchling of 2004 was recaptured in 2005 at the same location of its first capture in Loh Baru, Rinca. Another hatchling was recaptured a year (March 2006) after its emergence in 2005 approximately 1500 m from its initial capture location in Loh Buaya, Rinca (Figure 5.1a). On the contrary, juveniles showed a higher degree of recapture than hatchlings. From a total of 304 juveniles tagged, 74 of them were annually recaptured during the study period. Most juveniles displayed a very short distance of movement (< 100 m; Figure 5.1b, 5.1c). Twenty-two (28.95 %) individual juveniles were recaptured within the same locations of their first captured. Both hatchlings and juveniles showed no significant difference between daily and annual movement from WTR data and annual recapture data, respectively, (Paired T test; t 1,75 = -0.19, p = 0.85) (Table 5.2). However, there was a significant difference between farthest daily movement and farthest annual movement (Paired T test; t 1,75 = 2.05, p = 0.04) (Table 5.2). Annual distance and farthest annual movement in juveniles showed a significant differences among valleys (Chi square test; x2 = 593.33, p ≤ 0.01 and x2 = 1029.01, p ≤ 0.01) and between islands (Chi square test; x2 = 36006.11, p ≤ 0.01 and x2 = 53528.18, p ≤ 0.01) (Table 5.2). There was no record of movements between adjacent valleys within island and neither for between adjacent islands. Slope degree was negatively correlated with the size of the valley and the nearest peak elevation (Pearson correlation test; r = -0.75, p ≤ 0.01 and 0.66, p ≤ 0.01) (Table 5.3). On the other hand, slope degree was not significantly different among valleys (Chi square test; x2 = 6.18, p ≤ 0.52) (Table 5.3). Distance of daily movement and farthest daily movement from WTR data during trapping session showed a significant correlation with area (valley) size (Pearson correlation test; r = 0.32, p ≤ 0.01 and r = 0.41, p ≤ 0.01) in juveniles. There was also a significant correlation between distance annual movement and area size (Pearson correlation test; r = -0.12, p

57 ≤ 0.01) and between farthest annual movement and area size (Pearson correlation test; r = 0.34, p = 0.02). Distance in annual movement and farthest annual movement showed a significant negative correlation with slope degree (Pearson correlation test; r = -0.399, p ≤ 0.01, and r = -0.399, p ≤ 0.01, respectively). In contrast, both annual movement and farthest annual movement distance were not significantly correlated with vegetation types (Pearson correlation test; r = 0.07, p ≤ 0.63, and r = 0.16, p = 0.30). Distance to the nearest island was significantly different among islands (Chi square test; x2 = 14036.88, p ≤ 0.001) and significantly correlated with size of the island (Pearson correlation test; r = 0.90, p ≤ 0.01) (Table 5.5). Daily and farthest daily movement was significantly correlated with size of the island (Pearson correlation test; r = 0.88, p ≤ 0.01 and r = -1.00, p ≤ 0.01). There was also a significant correlation between daily and distance between island (Pearson correlation test; r = 0.61, p ≤ 0.01) and between farthest daily and the distance (Pearson correlation test; r = 0.95, p ≤ 0.01). Annual and farthest annual movement were showed a negative significant correlations with both size of island and distance between island (Pearson correlation test; r = -0.99, p ≤ 0.01, r = -0.79, p ≤ 0.01, r = -1.00, p ≤ 0.01, and r = 0.88, p ≤ 0.01, respectively).

5.4

DISCUSSION

Many authors define dispersal as movement away from one location to another location, being it to move away from natal sites, to look for suitable breeding opportunities, to find an unoccupied habitat, or to either avoid a conflict or competition with other conspecifics (van Dyck & Baguette 2005; Grant 1978; Greenwood 1980). In this study, dispersal was defined as movement of young Komodo dragons to the adjacent valleys or adjacent islands in term of accession of gene flow exchange between local populations. The aim of this study was to measure movement patterns and site fidelity in the early life stages of Komodo dragons. Based on three years of mark recapture data, this study has documented the first information on dispersal ability of Komodo dragons during early life stages. In general, movement

58 in juveniles was influenced by spatial characteristics, i.e. topographical setting and size of the valley. Table 5.2 Distance of movement of juvenile Komodo dragons (m). ISLAND / Farthest Farthest Daily Annual Location Daily annual KOMODO 368.26 714.33 579.78 476.63 Loh Sebita 916.25 658.75 873.86 1185.77 Loh Liang 967.92 862.33 577.74 753.88 Loh Lawi 1129.45 761.73 507.67 594.36 Loh Wau 461.00 343.80 419.69 344.25 RINCA 389.81 629.20 650.93 540.95 Loh Buaya 882.14 617.95 838.41 1008.86 Loh Baru 1013.29 756.33 746.33 778.76 Loh Tongker 594.00 432.14 1120.69 1330.54 Loh Dasami 594.00 432.14 469.44 475.45 Gili Motang 225.62 555.75 563.29 702.62

Table 5.3 Topographical barrier’s scores of each study area.

Location

Area Size (km2)

Nearest Peak (m)

5.81 8.94 10.03 0.83 5.50 5.48 2.64 3.54 5.35

181.24 181.24 231.82 301.67 126.81 253.11 272.10 326.76 234.34

Loh Sebita Loh Liang Loh Lawi Loh Wau Loh Buaya Loh Baru Loh Tongker Loh Dasami TOTAL/MEAN

Distance to the nearest peak (m) 889.93 889.93 954.73 909.27 913.46 597.82 533.67 830.43 814.90

Slope degree

Vegetation type

4.33 4.33 3.46 9.11 3.61 7.84 6.74 5.22 5.58

Table 5.4 Distance between islands in Komodo National Park Island Komodo Padar Rinca Nusa Kode Gili Dasami

Area size (km2) 311.59 14.09 204.78 7.33 9.48

Mean distance to nearest island (m) 12981.43 5012.00 4670.50 1206.66 3576.67

2.82 2.82 2.61 2.60 2.78 2.12 2.14 1.00 2.36

59 Both hatchlings and juveniles displayed low degrees of long distance movement enabling them to cross into other valleys or among islands. Indeed, due to low number of recaptures, it was difficult to measure movement capacity of hatchlings in terms of their natal dispersal. The mark recapture method used in this study may have limitations and underestimate records on dispersal events. Previous studies on dispersal applying mark-recapture methods have reported similar results (Roper et al. 2003). During the study, there was no record of within trip recapture or resight on hatchlings, thus daily movement of hatchlings could not estimated. No captured hatchling were recaptured nor even resighted after captured, either from nest or from traps, during the mark-recapture study session. This study showed a low degree of recapture opportunities for hatchlings. This might be due to arboreal tendency of hatchlings and their tendency to stay in the same tree for a long period of time (approximately 9 days; see chapter IV). After a year, one hatchling was recorded did not move at all from its first capture location. This hatchling was recaptured at the same location one year after its first capture. In contrast, another hatchling displayed long distance movement during the first year of its life. Radiotracked hatchlings (see chapter IV) displayed a relatively slow and short distance movement during their first month after emergence. However, it is difficult to conclude that hatchling Komodo dragons exhibit either site fidelity or long distance natal dispersal during their early stage of life. During their early life stage, Komodo dragons exhibit poor long distance movement ability. Juveniles did not move more than 2000 m, either for daily movement or for annual movement, and there was no record of any movement to adjacent valleys, or to adjacent islands. In contrast, most juveniles displayed short distance movement (<500 m). This result is similar to short distance dispersal pattern in juveniles of the Tasmanian Snow skink (Niveoscincus microlepidotus) (Olsson & Shine 2003). Sutherland et al. (2000) documented that dispersal in juvenile birds and mammals often involve short distance movement, while long distance was uncommon.

60 This study suggests that movement in hatchlings and juveniles to adjacent valleys was limited by topographical settings of the valleys (table 5.4); i.e. high degree of slope. Radiotelemetry data suggested that juveniles did not cross hills between valleys during the study (Chapter IV). It was evident that landscape features, such as mountain slope may strongly influence movements in early life stage of the species. Olsson and Shine (2003) suggested that site preferences might influence neonates to be less dispersed. Dahl and Willebrand (2005) reported that the philopatry pattern was related to the low natal dispersal and high degree of adult site fidelity. During the three years of the study, there was no evidence of juvenile Komodo dragon dispersing to adjacent islands. Even though Komodo dragons are able to swim, the ocean may be a main geographical barrier preventing dispersal between adjacent islands (Ciofi 2002). Manel et al. (2003) suggested that landscape features, i.e. mountains, stream, and ocean, might influence the pattern of gene flow and population structure. Dispersal is influenced by propensity of dispersers (Kawecki & Holt 2002) and distances in dispersal are influenced by cost of dispersal, i.e. increase of mortality (Roze & Rousett 2005). Lenormand (2002) suggested that dispersal might affect the offspring’s survival in nature, for instance because of maladaptive mechanism of the individual to the new environment. Sarno et al. (2003) suggested that dispersal in juvenile could increase the mortality rate via adult predation. Yet, Waser (1996) suggested that variation in cost and benefit or dispersal were influenced by a variety factors, i.e. social behaviour, fitness effect of dispersal, and intra-sexual conflicts. Extensive movement in Black rate snakes was suggested to have a correlation with out-breeding opportunity (Blouin-Demers & Weatherhead 2002). Long distance movement is critical for exchanging genetic information (Trakhtenbrot et al. 2005). However, based on this study, juvenile Komodo dragons displayed a tendency to site fidelity and suggested reduced out-breeding opportunities when they reach for adult. Hadany et al. (2004) noted that high fitness animal show their tendency to settle to their natal site and might be increased the potential for inbreeding when they reached reproductive maturity.

61 In addition, this study suggested that movement and fidelity in hatchling and juvenile Komodo dragons may have an implication to the gene flow. Ciofi (2002) described genetic variability among island populations for Komodo dragon. High degrees of similarity were found between Rinca and nearby islands (Nusa Kode and west coast of Flores) whereas, populations from Komodo and Gili Motang showed significant differentiation from other island populations. Decreases in genetic variability may relate to population isolation due to increase in spatial distance (Lensen et al. 2005). Kawecki and Holt (2002) noted that low immigration would decrease population sustainability. Genetic similarity in small populations could happen if dispersal is rare (Gomppers 1998). Several reproductive and physiological deficiencies in small populations may result from an increase in the level of inbreeding and low genetic variability and in turn affect population viability (Ciofi et al. 2002). Genetic variability can be maintained with at least one disperser per generation (Mills & Allendrof 1996). However, the current population size of the Komodo dragons might not be adequate to maintain genetic variation (Ciofi & Bruford 1999). This species is characterized by a long history of isolation by geographical barriers with a high degree of genetic distinctiveness and a significantly low level of gene exchange with other subpopulations and may retain the potential to develop adaptation to distinct environmental condition (Ciofi 2002). However, further studies are required to investigate if hatchling and juvenile Komodo dragons adopt natal philopatry and do not disperse.

CHAPTER VI

GENERAL DISCUSSION

6.1

GENERAL DISCUSSION

Successful biological conservation requires are to understand patterns and processes in spatial ecology of the species (Collinge 2001). Patterns in dispersion and use of space by species are critically linked to how managers decide management tactics (Daltrop et al. 2000). Studies on spatial and habitat use could provide useful information for the conservation strategies of endangered species (McDaniel et al. 2000).

An important finding from this study was that, during the early stage of their life, Komodo dragons have small activity areas with a high degree of overlap, and do not move long distances. Hatchlings displayed a linear fashion of movement from their nest that appeared to underpin a deliberate type of dispersal behavior to move as far as possible from their nesting sites. Juveniles, in turn, displayed their ability to explore their environment and occupied larger areas than hatchlings. Movement in hatchlings and juveniles are important in term of finding suitable habitat to avoid competition with larger conspecifics, expanding their distribution and maintain genetic variability of the population (Lebreton et al. 2003; Pough et al. 2001; Sarno et al. 2003; Sutherland 2000; Trakhtenbrot et al. 2005).

Forest coverage plays an important role for both hatchling and juvenile Komodo dragons as shown by the extensive use of arboreal habitats. Both hatchling and juvenile Komodo dragons displayed their preference for a particular tree (i.e. Tamarindus indica) and particular terrestrial setting (i.e. rock crevices) for shelter. This tendency showed the importance of trees during their early life-stage particularly

63 in avoiding cannibalism by larger Komodo dragons. Webb and Shine (1997) documented that understanding spatial and habitat requirements in reptiles could assist managers in determining their vulnerability to disturbances.

Based on mark-recapture data, this study showed evidence of low degree of long distance movement by young Komodo dragons. There was no record of either hatchling or juvenile performing long distance movements to the adjacent valleys, or to adjacent islands. Movement in Komodo dragons, particularly young, was constrained by landscape features. This, in turn, limited exchanges between local populations would decrease survival probability of small and isolated population.

Brooker et al. (1999) suggested that survival probability in small populations and isolated subpopulations is dependent on their ability to disperse. Dispersal is critically important for species conservation in relation to the impact of natural and human disturbances (Trakhtenbrot et al. 2005). Ciofi and de Boer (2004) documented declines in distribution and population density of Komodo dragons during the last three decades (Auffenberg 1981).

Given their limited dispersal abilities, this age class of Komodo dragons are in a precarious situation, and vulnerable to both natural and anthropic threats. Ciofi (2002) mentioned that potential natural threats included active volcanoes adjacent to the habitat. Ciofi and de Boer (2004) noted that decline in the extant population of Komodo dragons was influenced by habitat fragmentation and poaching activities. It has been documented that natural and anthropogenic factors are the major causes of species extinction within last decades (Kull et al. 2006).

6.2

RECOMMENDATIONS

Dispersal in animals plays an important role in their population dynamics and genetic variability (Trakhtenbrot et al. 2005; Grant 1978). Dispersal was suggested as a mechanism to maintain small populations and stabilized the overall population through recolonization and as a source of genetic variability (Reed et al. 1998). Blouin-Demers and Weatherhead (2002) described how movements had a significant

64 impact to the gene flow mechanism in black rat snakes (Elaphe obsoleta) which was represented by the mating system between male and females from different subpopulations.

The absence of dispersal may put small populations at risk of local extinction due to inbreeding depression and genetic drift (Madsen et al. 1996; Konuma et al. 2000). Limited inter-island dispersal over long periods of time may result in insular alteration (Sinclair 1998). Losos (2004) documented that the adaptation of the Greater Antillean anoles was correlated to isolation by insular and within island mechanisms. Ciofi (2002) has documented the genotypic differences among insular populations, particularly for the most isolated island, Gili Motang. This sub-population is the most severely at risk (Jessop et al. 2006 in press). Limitation in genetic variation due to insular adaptation has the potential to harm the extant populations of Komodo dragons which are declining due to natural or anthropic causes.

Dispersal information can be used to develop biological population models and direct conservation management decisions, i.e in forecasting rate of animal spread, reintroduction strategies, or maintaining adequate genetic and population viability (Trakhtenbrot et al. 2005). The declining status of Komodo dragons makes it appropriate to undertake intervention measures by the park management. Since the dispersal ability of this species during their early life stage is limited, a feasible option to manage the population should be considered before the population becomes too small for conservation options. Protecting remain suitable habitats is the most important aspect for the conservation of this species (Buij et al. 2002; Galanti et al. 2005 in press; Primack 2004).

Augmentation of this endangered species could be considered by managers as one of conservation strategies in order to maintain genetic variability and population viability. However, augmentation might be considered as a good option only when limiting factors can be addressed. Tweed et al. (2003) suggested that species augmentation should consider following factors; 1) location of the historical range of the species; 2) habitat quality and food resource availability; 3) long term security and access for further monitoring and research.

65

Finally, further long-term studies are needed to address the lack of detailed knowledge on the spatial ecology of this vulnerable species. Detailed ecological studies may provide a critical basis for management and conservation planning (Webb & Shine 1977). In addition, dispersal models can be used to predict which group or populations is likely to be the most vulnerable to disturbance and allow managers to test the merits of alternative habitat conservation strategies (Sutherland et al. 2000).

CHAPTER VII

CONCLUSION

This study has documented that, during their early life stage, Komodo dragons have small activity areas with a high degree of overlap, and do not move long distances. There was no record of either hatchlings or juveniles performing a long distance movement to the adjacent valleys, neither to adjacent islands. Movement in Komodo dragons, particularly young, was constrained by landscape features.

Hatchlings displayed a linear mode of movement that appeared to underpin a deliberate type of dispersal mechanism to move as far as possible from their nesting sites. Juveniles, in turn, displayed an ability to explore their environment and occupied larger areas as compared to hatchlings. Movement is an important mechanism in hatchlings and juveniles in terms of finding suitable habitat, so as to avoid competition with larger conspecifics, expanding their distribution and maintain genetic variability of the population.

This study also showed that forest coverage plays an important role for both hatchling and juvenile Komodo dragons. Both hatchling and juvenile Komodo dragons displayed a preference for open forest with a particular tree (i.e. Tamarindus indica) and particular terrestrial setting (i.e. rock crevices) as shelter. This showed the importance of trees during their early life-stage particularly in avoiding cannibalism by adult Komodo dragons.

Since the dispersal of this species during their early life stage is limited, it may put the extant population of Komodo dragon at risk of local extinction due to

67 inbreeding depression and genetic drift. Several feasible options to manage the population should be considered before the population becomes too small for conservation options. Protecting remain suitable habitats is the most important aspect for the conservation of this species. Augmentation of this endangered species could be considered by managers as one of conservation strategies in order to maintain genetic variability and population viability. Finally, further long-term studies, especially on the hatchling and juvenile stages, are needed to address the lack of detailed knowledge on the spatial ecology of this vulnerable species.

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