“Periods of rapid warming are followed really closely by periods of decline in body size, and vice versa,” said Professor Weeks.
“It’s clear that there’s a third component–changes in body size and shape–that’s probably going to interact with changes in range and changes in timing to determine how effectively a species can respond to climate change.”
The research was done in conjunction with the Field Museum in Chicago where ornithologists had collected tens of thousands of birds from the local area.
Collection manager, Dave Willard, has collected more than 100,000 birds from the streets of the city which died while migrating between Canada and South America in the Spring and Autumn.
The city is situated on a major migration path for birds such as sparrows, thrushes and warblers, with over 600 million birds dying every year in America because of tall buildings.
“When we began collecting the data analyzed in this study, we were addressing a few simple questions about year-to-year and season-to-season variations in birds,” said the Field Museum’s Willard.
“The phrase ‘climate change’ as a modern phenomenon was barely on the horizon. The results from this study highlight how essential long-term data sets are for identifying and analyzing trends caused by changes in our environment.”