Movement and Resource Selection by Feral Goats In
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MOVEMENT AND RESOURCE SELECTION BY FERAL GOATS IN A HAWAIIAN MONTANE DRY LANDSCAPE A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI‘I AT MĀNOA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN NATURAL RESOURCES AND ENVIRONMENTAL MANAGEMENT (ECOLOGY, EVOLUTION, AND CONSERVATION BIOLOGY) AUGUST 2012 By Mark William Chynoweth Thesis Committee: Creighton M. Litton, Co-Chairperson Christopher A. Lepczyk, Co-Chairperson Steven C. Hess Acknowledgements The work presented in this thesis is a result of an extensive collaboration between the Wildlife Ecology Lab and Ecosystem Ecology Lab at the University of Hawai‘i at Mānoa, the Institute for Pacific Islands Forestry of the USDA Forest Service, the Global Ecology Lab at Stanford University, and many other professionals, academics, students and citizens who helped me along the way. I would like to thank all those involved in this collaboration for the opportunity to complete this research. This research was supported by the National Science Foundation Graduate Research Fellowship (Grant No. 2010094953 to M. Chynoweth); USDA Forest Service, Pacific Southwest Research Station, Institute of Pacific Islands Forestry (Research Joint Venture 08-JV-11272177-074 to C.M. Litton); and the W.T. Yoshimoto Foundation Endowed Fellowship in Animal Wildlife Conservation Biology (to M. Chynoweth). I would like to thank the co-chairs of my committee, Drs. Creighton M. Litton and Christopher A. Lepczyk for their help throughout my experience at the University of Hawai‘i at Mānoa. This work would not have been possible without them. I would also like to thank my third committee member, Dr. Steve Hess, for his invaluable advice during all stages of this research, particularly relating to the associated fieldwork. I would also like to thank Ben Kawakami and his crew from Keepers of the Land for assistance with animal capture, Susan Cordell and Erin Questad for logistical advice and office space at the Institute of Pacific Islands Forestry, and the many individuals who helped with my field work, which often entailed driving long distances to locate goats. Thanks to: Darcey Iwashita, Joey Quitan, Nathan Friday, Isaac Ito, Nick Holmes, Nick Arpaia and Laura Berbusse. Special thanks to Lisa Ellsworth-Johnson, Alex Dale and Patrick Curry for help with geospatial analysis. I would also like to thank my friends and family for their support during my long journey as a M.S. student. ii Abstract Where animals range and how they select resources have long been of interest to ecologists and have recently merged together in the field of movement ecology. While movement ecology offers improved understanding of basic ecological questions, it also offers great potential for applied questions. To advance our understanding of movement, I sought to investigate how large herbivores respond to vegetation phenology and to determine if high-resolution remotely sensed data could predict resource selection. To address these objectives 12 feral goats were tracked with GPS satellite collars for one year in the Pōhakuloa Training Area on Hawai‘i Island. Results suggest that vegetation phenology is a good indicator of feral goat habitat. Feral goats primarily select habitats with low canopy height, high slope and curvature, and high values of photosynthetic and non-photosynthetic vegetation. Ultimately, the results of this study can be used to prioritize conservation activities in native Hawaiian montane dryland ecosystems. iii Table of Contents PAGE Acknowledgements…………………………………......………………………….. ii Abstract ……………………………………………………………………............. iii List of Tables ……………………………………………………………………… vi List of Figures ……………………………………………………………............... vii CHAPTER 1 Introduction………………………………………………………… 1 CHAPTER 2 Biology and impacts of Pacific Island invasive species: Capra hircus, the feral goat……………………………………………….. 6 Abstract…………………………………………………………………….. 6 Introduction………………………………………………………………… 7 Description and Account of Variation…………………............................... 7 Diet…………………………………………………………………………. 8 Environmental Impacts and Economic Importance………………………... 8 Geographic Distribution in the Pacific Region……….................................. 13 Habitat………………………………………………………………............ 13 History of Introductions……………………………………………………. 14 Physiology and Behavior…………………………………………………... 15 Reproduction……………………………………………………….. ……... 16 Population Dynamics………………………………………………………. 17 Management………………………………………………………………... 18 Prognosis…………………………………………………………………… 21 CHAPTER 3 Dispersal and home range use of non-native feral goats in a Hawaiian montane dry landscape………………………………….. 25 Abstract…………………………………………………………………….. 25 Introduction………………………………………………………………… 26 Materials and Methods……………………………………………………... 29 Results………………………………………………………………............ 35 Discussion………………………………………………………………….. 37 Management Implications………………………………………………….. 40 iv CHAPTER 4 Resource selection by feral goats in a Hawaiian montane dry landscape …………………………………………………………... 55 Abstract…………………………………………………………………….. 55 Introduction………………………………………………………………… 56 Materials and Methods……………………………………………………... 58 Results………………………………………………………………............ 64 Discussion………………………………………………………………….. 66 CHAPTER 5 Conclusions…………………….…………………………………... 80 References…….…………………………………………………………................. 84 APPENDIX A Table of Body Condition Score Index.……………………….…... 101 APPENDIX B Typical dispersal movement of a feral goat moving between primary and secondary range……………………………………... 102 APPENDIX C RSF Model Rankings…………………………………………….. 103 v List of Tables TABLE PAGE Table 2.1. Presence of feral goats on select Pacific Islands………………………. 23 Table 3.1. Summary of individual captured goats………………………………... 42 Table 3.2. Fixed-kernel density estimates of home range and core-use area of 14 feral goats in the Pōhakuloa Training Area……………………... 43 Table 3.3. Distances between seasonal home ranges and departure dates………... 44 Table 3.4. Two-tailed probabilities for differences in relative NDVI values in primary and secondary ranges……………………….……………... 45 Table 4.1. Seven a priori models to consider for model selection……………….. 70 Table 4.2. Sum of individual AIC ranks of models for nocturnal selection……… 71 Table 4.3. Sum of individual AIC ranks of models for diurnal election…………. 72 Table 4.4. Estimated mean coefficients and SE for the population level RSF model for feral goats in the Pōhakuloa Training Area………………… 73 Table 4.5 Estimated mean coefficients and SE for the population-level diurnal and nocturnal resource selection function…………………………....... 74 Table A.1. Table of Body Condition Score Index………………………………… 102 Tables C.1 – C.18. Model rankings with for all RSF models…………………….. 104 vi List of Figures FIGURE PAGE Figure 2.1. Feral goats, Capra hircus, on Hawai‘i Island. Photo………………… 24 Figure 3.1. Location of Study Area, the Pōhakuloa Training Area………………. 46 Figure 3.2. Dominant vegetation types of the Pōhakuloa Training Area………… 47 Figure 3.3. Potential capture location and actual capture locations for feral goats in the Pōhakuloa Training Area………….…………………………… 48 Figure 3.4. Number of days collars were deployed on each individual…………... 49 Figure 3.5. Mean daily home ranges of feral goats……………………………….. 50 Figure 3.6. Mean daily association between individual goats……………………. 51 Figure 3.7. Frequency of feral goat group size…………………………………… 52 Figure 3.8. Utilization Distribution Overlap Index (UDOI) between annual ranges of collared feral goats…………………………………………. 53 Figure 3.9. Annual changes in mean NDVI in 95% primary and secondary home ranges for individuals demonstrating dispersal behavior……………... 54 Figure 4.1. Location of study area, the Pōhakuloa Training Area………………... 75 Figure 4.2. Dominant vegetation types of the Pōhakuloa Training Area………… 76 Figure 4.3. Potential capture location and actual capture locations for feral goats in the Pōhakuloa Training AreA…………………………………….... 77 Figure 4.4. Mean displacement distances (± SE) of all individuals between collar fixes by hour………………………………………………….............. 78 Figure 4.5. Map depicting relative probability of diurnal and nocturnal habitat use by feral goats………………………………………………........... 79 Figure B.1. Typical dispersal movement of feral goat moving between primary and secondary range………………………………………………………. 103 vii CHAPTER 1 Introduction Once established, introduced species can become invasive and subsequently cause animal extinctions (Clavero and García-Berthou 2005), disassemble communities (Sanders et al. 2003) and cause environmental damage reaching up to $120 billion in the United States alone (Pimentel et al. 2005). As such, non-native, invasive species represent a major threat to island ecosystems and contribute significantly to overall human caused global environmental change (Vitousek et al. 1997a). Second only to habitat destruction, invasive species are considered one of the leading causes of biodiversity loss (Vitousek et al. 1997b). The impacts of invasion are often exacerbated in islands ecosystems, where native species have evolved in relative isolation. Introduced vertebrates present their own suite of challenges for natural resource managers. The history of introduced vertebrates in the Hawaiian Islands began with the arrival of Polynesians between 1219 and 1266 A.D (Wilmshurst et al. 2011). Early vertebrate introductions included the domestic pig (Sus scrofa), dog and jungle fowl, and unintended stowaways such as the Polynesian rat (Rattus exulans), geckos, and skinks