Ben-Gurion University of the Negev
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Ben-Gurion University of the Negev Jacob Blaustein Institutes for Desert Research Albert Katz International School for Desert Studies Foraging ecology, body temperature patterns and space use characteristics of the Nubian Nightjar, Caprimulgus nubicus, in Israel Thesis submitted in partial fulfillment of the requirements for the degree of "Master of Science" By: Yoav Perlman June 2007 2 Ben-Gurion University of the Negev Jacob Blaustein Institutes for Desert Research Albert Katz International School for Desert Studies Foraging ecology, body temperature patterns and space use characteristics of the Nubian Nightjar, Caprimulgus nubicus, in Israel Thesis submitted in partial fulfillment of the requirements for the degree of "Master of Science" By: Yoav Perlman Under the Supervision of Prof. David Saltz and Prof. Berry Pinshow Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev. Author’s Signature ..................................................... Date ...................... Approved by the Supervisor...................................... Date ...................... Approved by the Supervisor...................................... Date ...................... Approved by the Director of the School .................... Date ...................... 3 Foraging ecology, body temperature patterns and space use characteristics of the Nubian Nightjar Caprimulgus nubicus in Israel _________________________________________________________________ Yoav Perlman Thesis submitted in partial fulfillment of the requirements for the degree of "Master of Science" Albert Katz International School for Desert Studies, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev. June 2007 ABSTRACT Nightjars are the only nocturnal, aerial, insectivorous taxon of birds that locates its prey visually. As such, they are subject to substantial predation risk while foraging in periods of the night with relatively strong light intensity. Further, nightjars are small endotherms that often use facultative hypothermia in order to reduce energy costs during periods of low ambient air temperatures (Ta), or food shortage. The Nubian Nightjar (Caprimulgus nubicus, Lichtenstein, 1823) is a small nightjar (46 - 61 g) that breeds locally in southern Israel and the Israeli population is at serious risk of extinction. The goal of my research was to study the temporal and spatial activity patterns and body temperature variation, and their interactions, in the Nubian Nightjar, by exploring the direct and indirect effects of several environmental variables on these patterns, including Ta, light intensity and potential prey availability. From 2004 to 2006, I tracked seven Nubian Nightjars fitted with radio tags for a total of 73 nights in the Kikar Sdom region of southern Israel. I found that Nubian 4 Nightjars foraged more during periods of the night with stronger light intensity. I also found that they probably trade-off safety with foraging efficiency by using periods with crepuscular sunlight (after dusk and before dawn) on nights with no moon, but avoid foraging at these hours when moonlight is strong. I also found that Nubian Nightjars forage during periods when noctuid moth activity peaks. Nubian Nightjars use facultative hypothermia regularly, and do so more on cold nights, and on nights when light intensity is low, when foraging opportunities are limited. This is the first reported indication that light intensity might act as a cue for entry into torpor by a bird. Finally, I found that Nubian Nightjars have relatively small home ranges, which include patches of salt marsh which they use almost exclusively for roosting and breeding, and forage mainly in open habitats, including agricultural fields. In designing a conservation scheme for this species in Israel, habitat structure, protection of water sources and light pollution must be taken into account. ACKNOWLEDGEMENTS I thank Arnon Tsairi, who first introduced me to the Nubian Nightjars at Ne’ot Hakikar, motivated me to begin with the research and helped me hugely in the field with his intimate knowledge of the nightjars. I thank both my advisors, Profs. David Saltz and Berry Pinshow, for their patience and trust during all the stages of this work. Their valuable suggestions and remarks during the research improved it greatly. I thank Dan Alon, director of the Israeli Ornithological Center for financial support to this project and for use of equipment. I’d like to thank all the people who helped me with the strenuous fieldwork: Yair Dalbar, Zeev Shahar, Gal Abdu, Ido Tsurim, Michał Wojciechowski, Rami Mizrahi, Dubi Shapiro, Sameh Darawshe, Amir Balaban, Yoni and Lior Belmaker, Gidon Perlman, and Uri Makover. Amir Balaban 5 helped in filming the nightjar behavior in the field. My thanks go also to Nir Sapir and Ido Tsurim for their help in data analysis. Dr. Amos Bouskila and Haim Berger helped much with the telemetry work and equipment. Special thanks to Michał Wojciechowski, Shai Daniel, Niv Palgi and Carmi Korine who provided important help with the body temperature work. Thanks to Dr. Andrew McKechnie for granting me permission to use his energetic benefit model. I thank the residents of Neot Hakikar and Ein Tamar for allowing me access to their fields (and often houses too). Their hospitality and flexibility permitted this work to be done. Special thanks go to Ehud Tsairi, resident of Neot Hakikar and father of Arnon, who helped me much with supplying equipment and introducing me to his fellow farmers, and made my work much easier. I thank Harel Ben Shahar of the Nature and Parks Authority for his invaluable support and help to the project. Thanks also the Caracal unit of the Israel Defense Forces, for permitting my stay in such a sensitive area at night. Thanks to Ami Maduel from the Jewish National Fund research station at Ein Tamar for the use of the meteorological data he recorded for the Israel Meteorological Service. Special thanks to Vasiliy Kravchenko of Tel Aviv University for sharing his knowledge and data of moth activity, and to Eran Levin for his help with analysis of nightjar pellets. My M.Sc. studies were supported by a scholarship of the Albert Katz International School for Desert Studies Foundation. I also received support from the Ornithological Society of the Middle East (research grant 3/2006) and from the Gidi Zakkay fund, for which I am most grateful. Last, and most importantly, I thank my wife Adva for her endless support, during all stages of the research and my dog Leica for her patient company during the long nights in the field. Without their support this research would not have been possible. 6 TABLE OF CONTENTS Abstract ........................................................................................................................ 3 Acknowledgements ...................................................................................................... 4 Table of contents .......................................................................................................... 6 List of tables and figures .............................................................................................. 7 Introduction .................................................................................................................. 8 Hypotheses and predictions ............................................................................ 13 Methods ...................................................................................................................... 14 Study site ........................................................................................................ 14 Nightjar activity and body temperature patterns ............................................ 15 Environmental conditions .............................................................................. 17 Data analysis .................................................................................................. 18 Results ........................................................................................................................ 22 General ........................................................................................................... 22 Foraging activity patterns ............................................................................... 23 Body temperature patterns .............................................................................. 30 Space use characteristics ................................................................................ 34 Discussion .................................................................................................................. 39 Foraging activity patterns ............................................................................... 39 Body temperature patterns .............................................................................. 41 Space use characteristics ................................................................................ 47 Conservation implications .............................................................................. 47 References .................................................................................................................. 51 Appendix 1: The food of the Nubian Nightjar ........................................................... 57 7 Appendix 2: Moth activity patterns at Neot Hakikar ................................................. 58 Appendix 3: Aspects in the natural