Publication Date
2020
Journal or Book Title
Proceedings Of The National Academy Of Sciences
Abstract
Breeding timed to match optimal resource abundance is vital for the successful reproduction of species, and breeding is therefore sensitive to environmental cues. As the timing of breeding shifts with a changing climate, this may not only affect the onset of breeding but also its termination, and thus the length of the breeding period. We use an extensive dataset of over 820K nesting records of 73 bird species across the boreal region in Finland to probe for changes in the beginning, end, and duration of the breeding period over four decades (1975 to 2017). We uncover a general advance of breeding with a strong phylogenetic signal but no systematic variation over space. Additionally, 31% of species contracted their breeding period in at least one bioclimatic zone, as the end of the breeding period advanced more than the beginning. We did not detect a statistical difference in phenological responses of species with combinations of different migratory strategy or number of broods. Nonetheless, we find systematic differences in species responses, as the contraction in the breeding period was found almost exclusively in resident and short-distance migrating species, which generally breed early in the season. Overall, changes in the timing and duration of reproduction may potentially lead to more broods co-occurring in the early breeding season—a critical time for species’ reproductive success. Our findings highlight the importance of quantifying phenological change across species and over the entire season to reveal shifts in the community-level distribution of bird reproduction.
DOI
https://doi.org/10.1073/pnas.1913579117
Volume
117
Issue
31
Pages
18557-18565
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
License
UMass Amherst Open Access Policy
Recommended Citation
Hällfors, Maria H.; Antão, Laura H.; Itter, Malcolm; Lehikoinen, Aleksi; Lindholm, Tanja; Roslin, Tomas; and Saastamoinen, Marjo, "Shifts in timing and duration of breeding for 73 boreal bird species over four decades" (2020). Proceedings Of The National Academy Of Sciences. 423.
https://doi.org/10.1073/pnas.1913579117