The breeding seasons of wild house finches are shifting due to climate change, according to new research from Washington State University.
The effect of climate change on the breeding season of birds has been documented before but in a limited context.
Heather Watts, an avian physiologist, reported her finding in Ibis, the International Journal of Avian Science.
“We know that many birds are breeding earlier as temperatures get warmer,” says 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.”
How Temps Affect Breeding Habits
Studying seed-eaters is crucial because it can help clarify how temperature is affecting breeding habits.
It’s still uncertain if the temperature is having a direct effect on the animals or if it causes indirect effects like shifts in the timing of plant growth.
Previous studies suggest that plant-eating animals are likely to experience stronger effects due to climate change compared to those that eat other foods because of these indirect influences.
Studying House Finches
To clarify these effects, Watts studied when house finches lay eggs.
House finches are an abundant bird often seen at backyard feeders throughout the United States.
Watts and her coauthors gathered museum records of house finch nests found in California between 1895 and 2007 and paired these records with spring temperature data for the regions where the nests were located.
“For every degree Celsius increase in temperature, they’re laying about four-and-a-half days earlier,” says Watts, an associate professor in WSU’s School of Biological Sciences.
Climate Change Has Stronger Effects on Plant-eaters
The magnitude of this shift was large compared to studies of other species, which fits with predictions that climate change would have stronger effects on plant-eaters than other animals.
These results aren’t necessarily problematic for the house finch.
The birds could be changing their breeding timing to match the availability of seeds.
This shift could even be beneficial if birds take advantage of the longer breeding season to make multiple nests and have more offspring.
“We have no evidence that under current conditions this is a problem for house finches,” says Watts.
“But as the 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.”
In fact, while this species is expanding into new areas of North America, it is declining in some parts of its native range.
Animals have vastly different needs concerning food and habitats.
Studies like these are essential to understanding the subtle and possibly unique effects that climate change can have on different species.