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.

Keywords

Ayes; global change; life history strategies; reproduction; phenology

Published in

Proceedings of the National Academy of Sciences of the United States of America
2020, Volume: 117, number: 31, pages: 18557-18565
Publisher: NATL ACAD SCIENCES

SLU Authors

• Roslin, Tomas

  • Department of Ecology, Swedish University of Agricultural Sciences
    
  • University of Helsinki

UKÄ Subject classification

Ecology
Climate Research
Zoology


Publication identifier

DOI: https://doi.org/10.1073/pnas.1913579117

Permanent link to this page (URI)

https://res.slu.se/id/publ/108328