The relative influence of cross‐seasonal and local weather effects on the breeding success of a migratory songbird

• Published in: Journal of Animal Ecology
• Main Authors: de Zwaan, Devin R., Drake, Anna, Camfield, Alaine F., MacDonald, Elizabeth C., Martin, Kathy
• Other Authors: American Ornithological Society, Canadian Network for Research and Innovation in Machining Technology, Natural Sciences and Engineering Research Council of Canada, Environment and Climate Change Canada, Polar Knowledge Canada, Society of Canadian Ornithologists, University of British Columbia, Natural Sciences and Engineering Research Council of Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: British Columbia; Canada; Eremophila alpestris
• Online Access: http://dx.doi.org/10.1111/1365-2656.13705; https://onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2656.13705; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/1365-2656.13705; https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2656.13705

Abstract In seasonal environments, fluctuating early‐season weather conditions and short breeding windows limit reproductive opportunities such that breeding earlier or later than the optimum may be particularly costly. Given the risk of early‐season energy limitations, time‐ and energy‐based carry‐over effects stemming from environmental conditions across the annual cycle may have pronounced consequences for breeding phenology and fitness. Generally, when and where environmental conditions are most influential are poorly understood, limiting our ability to predict the future of climate‐sensitive populations. For an alpine‐breeding, migratory population of horned lark Eremophila alpestris in northern British Columbia, Canada (54.8°N), we assessed how weather conditions across the annual cycle influenced clutch initiation date and offspring development. We also addressed how cross‐seasonal effects on breeding parameters combine to influence reproductive fitness. With 12 years of breeding data and 3 years of migration data, we used a sliding window approach to identify points during the annual cycle when weather events most influenced breeding phenology and offspring development. Consequences for breeding success were assessed using nest survival simulations. Average clutch initiation date varied up to 11 days among years but did not advance from 2003 to 2019. Warmer temperatures at stopover and breeding sites advanced clutch initiation, but winter conditions had no effect. Sub‐zero stopover temperatures carried over to prolong offspring development independent of clutch initiation date, potentially indicating energy‐based carry‐over effects acting on parental investment. Nest survival decreased with both later clutch initiation and prolonged offspring development such that females nesting earlier and fledging offspring at a younger age were up to 45% more likely to reproduce successfully. We demonstrate that stronger carry‐over effects originated from environmental conditions closer to the breeding site in time ...