Western University Scholarship@Western Electronic Thesis and Dissertation Repository 12-3-2018 2:00 PM Landscape-level effects of agricultural intensification on the condition and diet of nestling Barn Swallows (Hirundo rustica) Jackson W. Kusack The University of Western Ontario Supervisor Hobson, Keith A. The University of Western Ontario Graduate Program in Biology A thesis submitted in partial fulfillment of the equirr ements for the degree in Master of Science © Jackson W. Kusack 2018 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Other Ecology and Evolutionary Biology Commons Recommended Citation Kusack, Jackson W., "Landscape-level effects of agricultural intensification on the condition and diet of nestling Barn Swallows (Hirundo rustica)" (2018). Electronic Thesis and Dissertation Repository. 5900. https://ir.lib.uwo.ca/etd/5900 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Abstract Farmland bird populations have experienced declines with increasing agricultural intensification for which the leading hypothesis is a reduction of prey insects. This may be especially relevant for aerial insectivores whose primary diet is flying insects. For this thesis, I examined nestling body condition and used stable isotopes (δ13C, δ15N) and fecal DNA barcoding to determine the diet of a farmland breeding aerial insectivore, the Barn Swallow (Hirundo rustica), within an agro-ecosystem in Southern Ontario, Canada. Nestling body condition was positively affected by agricultural intensification, but all benefits were lost by the pre-fledging stage and with no effect on productivity. Stable isotopes indicated that nestling diet was derived from within agro-ecosystems. While nestling diet breadth was negatively affected by agricultural intensification, I found evidence for a robust dipteran diet unaffected by landscape. My results provide little evidence of long-term negative repercussions to breeding within agriculturally intense landscapes for the Barn Swallow. Keywords: agricultural intensification, Barn Swallow, Hirundo rustica, aerial insectivore, body condition, diet, DNA barcoding, nestling, row crop, stable-isotopes. i Co-Authorship Statement This thesis was conceived and designed by Jackson W. Kusack with the help of Keith A. Hobson from Western University and Environment and Climate Change Canada and Greg W. Mitchell from Environment and Climate Change Canada. Fieldwork was primarily conducted by Jackson W. Kusack with the help of Dean R. Evans, Greg W. Mitchell, and Michael D. Cadman of the Canadian Wildlife Service. All analyses and writing were done by Jackson W. Kusack. Dr. Keith Hobson and Dr. Greg Mitchell assisted writing by providing feedback and edits. Any resulting publications will be published with Keith A. Hobson, Greg W. Mitchell, Dean R. Evans, and Michael D. Cadman. ii Acknowledgements First, I thank Keith A. Hobson and Greg W. Mitchell for the opportunity to work with them on this project and for their endless support and patience. I could not have had better mentors throughout this process, and I am forever grateful for the knowledge I have gained from you both. I also thank Christopher G. Guglielmo and Jeremy N. McNeil for their guidance. A very special thank you to Dean R. Evans, Michael D. Cadman, and Kaelyn Bumelis for their collaboration on this project. Fundamentally, this project was a group effort and I would not have finished without their hard work. Dean for your support as my lab mate, friend, and source of constant late-night advice. Mike for your endless breadth of ornithological insights. Kaelyn for being a constant source of energy and making fieldwork enjoyable. I thank the many landowners who allowed us access to their farms, without which I would not have been able to do a project of this scale. I am also grateful to Sean McElaney, Andrew Beauchamp, and the many volunteers who helped in the field. Lastly, I thank my family and friends. Particularly, I thank my parents Mark Kusack and Megan West, and my grandparents Lynn and Keith Kusack, and Judith and Kenneth Russell, to whom I am eternally grateful for your love and support. iii Table of Contents Abstract ............................................................................................................................ i Co-Authorship Statement................................................................................................ ii Acknowledgements ........................................................................................................ iii Table of Contents ........................................................................................................... iv List of Tables ................................................................................................................. vi List of Figures .............................................................................................................. viii List of Appendices ......................................................................................................... xi List of Abbreviations .................................................................................................... xii Chapter 1 ..............................................................................................................................1 General introduction ........................................................................................................1 1.1. Agricultural intensification ................................................................................... 1 1.2. Aerial insectivores ................................................................................................ 4 1.3. Food availability ................................................................................................... 5 1.4. Body condition ..................................................................................................... 6 1.5. Diet ....................................................................................................................... 8 1.6. Objectives ........................................................................................................... 13 1.7. Literature cited .................................................................................................... 15 Chapter 2 ............................................................................................................................25 Landscape-level effects of agricultural intensification on the condition of nestling Barn Swallows (Hirundo rustica) ...........................................................................................25 2.1. Introduction ........................................................................................................ 25 2.2. Methods .............................................................................................................. 28 2.3. Results ................................................................................................................ 36 2.4. Discussion ........................................................................................................... 42 2.5. Conclusion .......................................................................................................... 52 2.6. Literature cited .................................................................................................... 54 Chapter 3 ............................................................................................................................60 Nestling diet of Barn Swallows (Hirundo rustica) in an agro-ecosystem: insights from fecal DNA barcoding and stable isotopes (δ13C, δ15N) ..................................................60 3.1. Introduction ........................................................................................................ 60 iv 3.2. Methods .............................................................................................................. 64 3.3. Results ................................................................................................................ 70 3.4. Discussion ........................................................................................................... 84 3.5. Conclusion .......................................................................................................... 91 3.6. Literature cited .................................................................................................... 93 Chapter 4 ..........................................................................................................................100 General Discussion ......................................................................................................100 4.1. Key findings ..................................................................................................... 100 4.2. Conservation implications ................................................................................ 102 4.3. Study assumptions ............................................................................................ 103 4.4. Future direction................................................................................................. 105 4.5. Conclusions .....................................................................................................