We are grateful to the numerous landowners in New York who granted permission to use their land to conduct our research, as well as the staff of Malheur National Wildlife Refuge for their cooperation and facilitation of our research. Numerous undergraduate students from Hartwick College provided invaluable assistance in the field, without which the work would have been impossible. Financial support was provided by National Science Foundation grants to MTM (BSR-9106854 and IOB-0539370), an NSERC grant from the Canadian Government, and additional student grants provided by the Forbes-Lea Fund of Portland State University, the Frank M. Chapman Fund from the American Museum of Natural History, the American Ornithologists’ Union Student Research Fund, and the Association for the Study of Animal Behaviour.
Avian Conservation and Ecology
Bird populations -- United States, Avian biology, Eastern Kingbirds
For many bird species, but especially aerial insectivores, reproduction depends on weather. Climate change is likely to intensify effects, but with uncertain consequences. We report 22 years of data on Eastern Kingbird (Tyrannus tyrannus) reproduction for two populations located in different hygric environments undergoing climate change; mesic central New York, USA, (NY; 12 years) and xeric southeastern Oregon, USA, (OR: 10 years). Laying date became earlier with increasing temperature in the 30-day period preceding laying in identical fashion at both sites, and in years of early laying, clutch size was larger, length of laying season increased, and failed initial nesting attempts were more often replaced. High temperature in the 10-days preceding mean laying date was associated with shorter laying seasons, while a site by 10-day temperature interaction reflected an increase and decrease of clutch size with increasing 10-day temperature in NY and OR, respectively. Seasonal rate of clutch size decline was higher when the laying season was short but also slowed in xeric OR when rain was abundant in the 10-days prior to mean laying date. Nest predation drove annual variation in young fledged/nest, but the latter also increased and decreased with increasing maximum temperature during the nestling phase in mesic NY and xeric OR, respectively. Potential effects of climate change on kingbird populations are thus high given the dependence of reproduction on weather, and climate change likely contributed to declines of kingbirds in OR. Declines of kingbirds in NY appear unrelated to warming climates because higher temperatures advanced laying dates and yielded greater nest productivity. However, length of laying season declined across years at both sites, and thus early season gains may be negated by poor conditions late in the season that may be causing shorter laying seasons. Further work is needed to identify causes for the latter changes.
Copyright © 2022 by the author(s). Published here under license by The Resilience Alliance. This article is under a Creative Commons Attribution 4.0 International License. You may share and adapt the work provided the original author and source are credited, you indicate whether any changes were made, and you include a link to the license.
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Murphy, M., Redmond, L., Dolan, A., Cooper, N., Shepherdson, K., Chutter, C., & Cancellieri, S. (2022). Weather and climate change drive annual variation of reproduction by an aerial insectivore. Avian Conservation and Ecology, 17(2).