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Climate change is altering the breeding seasons for seed-eating birds

A new study from Washington State University (WSU) has found that the breeding seasons of wild house finches are shifting due to climate change.

Study lead author Heather Watts is an avian physiologist and an associate professor in WSU’s School of Biological Sciences.

“We know that many birds are breeding earlier as temperatures get warmer,” said Professor Watts. “Almost all of those studies are on birds that eat insects or other animals. What we don’t know is if seed-eating birds are shifting the timing of breeding too.”

It is important for scientists to study seed-eaters to gain a better understanding of how temperature is affecting breeding habits. Experts are still trying to determine whether rising temperatures are having a direct or an indirect effect on the animals.

Previous studies have found that plant-eating animals are likely to experience stronger impacts due to environmental changes such as shifts in the timing of plant growth.

To investigate the magnitude of these effects, the researchers studied when house finches lay eggs. The team gathered museum records of house finch nests found in California between 1895 and 2007, and then compared these records against spring temperature data for the locations of the nests.

“For every degree Celsius increase in temperature, they’re laying about four-and-a-half days earlier,” said Professor Watts. This was a large shift compared to what is known of other species, which supports the theory that climate change will have stronger effects on plant-eaters.

According to the researchers, the study findings are not necessarily bad news for the house finch. The shift could even allow the birds to take advantage of the longer breeding season and have more reproductive success.

“We have no evidence that under current conditions this is a problem for house finches,” said Professor Watts. “But as climate continues to change, we could reach a point where birds are no longer able to either time breeding appropriately, or food resources could change in such a way that it has negative impacts on breeding.”

The study is published in the IBIS-International Journal of Avian Science.

By Chrissy Sexton, Staff Writer

Image Credit: Jessica Tir

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