A 47% decline in wind speed shapes phenology and selection on mismatching in Tree Swallows across a quarter century

A 47% decline in wind speed during laying and hatching in Tree Swallows (Tachycineta bicolor) in southeastern Wisconsin (1997–2023) reshaped phenology and relaxed selection on phenological mismatching.

• Why it matters: Climate-change studies often emphasize temperature and miss how wind and food availability jointly affect breeding timing and reproductive success, leaving selection pressures poorly characterized.
• What they did: Across 26 years, the authors analyzed breeding ecology in southeastern Wisconsin and used changepoint analysis to compare end-of-April versus early-May conditions, linking wind speed to food (Nematoceran flies) and mismatch timing.
• The result: Slower wind increased food availability, producing larger clutches, heavier nestlings, and greater fledging success over time, while later-nesting birds advanced laying; mismatching effects were relatively weak and selection against mistiming was relaxed.