A significant study from the University of Utah has divulged that migratory songbirds are molting their feathers up to a day earlier each year, a change researchers tie directly to the warming climate. The research, led by graduate student Kyle Kittelberger, observed this pattern over 13 years, focusing on the birds' feather shedding and regrowth, a crucial aspect of their survival related to flight, migration, breeding, and insulation.
In the fall, these birds show a clear trend of an earlier molt each year at the U's Bonderman Field Station at Rio Mesa, which is an indication of their adaptation to climate shifts. "Birds are shifting both their body and their flight feather molt earlier over time across the 13 years at a rate of about one day earlier per year," said Kittelberger, as per At The U. The patterns appear to be a response to changes in migration, and breeding times attributed to climate factors such as El Niño.
Examined through the lens of 22,072 birds, representing 134 species, captured from 2011 to 2024, the field station's data is a testament to these shifts. This facility is integral to the banding and tracking of these migratory species, which involves documenting species, sex, age, molt stage, and other vital data for understanding bird biologies.
Notably, the study, set for publication in The American Naturalist, did not find a similar trend in the spring molt at the community level. "We didn’t see any shift at the community level for spring body molt," Kittelberger explained, as obtained by At The U, considering this might be because birds migrate faster in the spring as they rush back to their breeding grounds, which reduces the window for molt. Other studies corroborate this finding, suggesting songbirds are kicking off breeding earlier due to the changing climate.
