Bird's plumage evolving as a result of climate change, study suggests

Climate change is causing the plumage of a small European bird to evolve, suggests a new study from Sweden.

The collared flycatcher, orFicedulaalbicollis, is a small bird that breeds in Europe andoverwintersin sub-Saharan Africa.

LarsGustafsson, of the Department of Animal Ecology, Evolutionary Biology Centre atUppsalaUniversityin Sweden, has been studying the speciessince 1980, collecting various data including about its plumage, which features aprominent ornament, or white patch, on the male's head.

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Usually these ornaments offer an advantage in breeding: a bigger and brighter one can attract mates. But thestudy byGustafssonand Simon Evans found that the patch was having the opposite result, something that the researchers attribute to rising spring temperatures at the breeding site.

In particular, the study showed that males with a large patch were favoured by mates after a cold breeding season, but notafter a warm one.

Years of shrinking

Gustafssonhad noticed over the years that the patch was progressively shrinking, but wasn't sure what was causing the change. He pored over data and saw a correlation with temperatures at the breeding sites. And there was a definite pattern to the shrinking head patch.

"It seems to have become a trend," he told CBC News.

The decline in size of the patch wasmore than 10 per cent, something that was "quite big," he said.

Birds with larger patches didn't fare as well in warmer years, as they were lesslikely to survive the winter.

While the study suggests that the change is in response to climate change, the authors acknowledge that they don't have an explanation for the shrinking head patch.

"We view this study as an openingrather than a conclusion," Gustafsson said.

In an articlein the same journal, Cody Dey, who is with the Great Lakes Institute of Environmental Research, University of Windsor, and James Dale commented on the study."There are reasons to predict that climate change will drive the evolution of new, or exaggerated, ornaments in some species. Just as climate change will lead to winners and losers in terms of species' abundance and distribution, it seems it may also lead to winners and losers in the global beauty pageant."

Climate change is having other effects on the birds. The flycatchers have already shifted their breeding by 10 days compared with the 1980s, when Gustafsson first began collecting data. This, he says, has been a result of their food sources insects emerging earlier as warmer temperatures occur sooner in the year.