Wind and rain play bigger role than temperature in breeding timing of tree swallows

Wind, rain play key role in breeding patterns of migratory tree swallows

April 27 2017 ScienceDaily  CU Boulder

Wind and precipitation play a crucial role in advancing or delaying the breeding cycles of North American tree swallows… [the study] underscores the importance of considering factors beyond temperature when examining how climate change might affect species’ biological niche.

…when…researchers tested how swallow nesting data from two different Alaskan sites corresponded with both daily and seasonal climate indicators like the number of windy days, days with measureable precipitation and average daily temperature, they found that windiness (or lack thereof) had the most consistent correlation with swallow breeding patterns over time…

…The results showed that a long-term decline in windiness (and to a more variable extent, rain) in central Alaska over the past decade-plus correlated with the birds’ earlier breeding much more strongly than temperature, indicating that wet, windy spring weather that may have delayed egg laying in the past is now less of an impediment for the swallows.

Rachel D. Irons, April Harding Scurr, Alexandra P. Rose, Julie C. Hagelin, Tricia Blake, Daniel F. Doak. Wind and rain are the primary climate factors driving changing phenology of an aerial insectivore. Proceedings of the Royal Society B: Biological Sciences, 2017; 284 (1853): 20170412 DOI: 10.1098/rspb.2017.0412