Polish Scientists Link Climate Change to Faster Bird Evolution on Gotland

A nearly 20‑year study by a team from Jagiellonian University, together with the University of New South Wales, has tracked two bird species on the Swedish island of Gotland. The researchers found that warmer springs are causing the white‑backed flycatcher to start breeding one to two weeks earlier and the blue tit to shift its breeding calendar by up to two and a half weeks.

Because the flycatcher migrates from Africa, it arrives with limited knowledge of local conditions and has less time to complete its brood before autumn migration, increasing competition for nest sites. The resident blue tit, which observes conditions year‑round, adapts more readily. The long‑term data suggest that climate‑driven changes in breeding timing may also influence the speed of evolutionary adaptation, as variability in traits and microbiome composition appear linked to the new environmental regime.