New study shows heavy rainfall killing peregrine chicks
“The nestlings died from hypothermia and in some cases, from drowning in their flooded nests"
An increase in heavy rainfall in the Canadian Arctic is posing a threat to the survival of one of the Arctic’s most efficient predators, the peregrine falcon.
Researchers at the University of Alberta and the Université de Québec have found that more frequent heavy rains — brought on by warmer summers — are responsible for a decline in the falcons’ reproduction.
The study was recently published in Oecologia, an ecology journal.
Looking at weather data along with falcons’ breeding success dating back 30 years, researchers conducted a nest box experiment outside of Rankin Inlet between 2008 and 2010.
During that time, falcon nests were monitored using motion sensitive cameras.
Images confirmed to researchers that a third of the recorded chick deaths were caused by rain, either in the nest boxes or on natural ledges.
“The nestlings died from hypothermia and in some cases, from drowning in their flooded nests,” said University of Alberta researcher Alistair Franke, in a news release. “Without constant parental care, they are most vulnerable to cold and wet conditions in the first three weeks of life.”
Researchers now say that heavy rainfall poses a threat not seen in this species since before pesticides like DDT were banned in Canada in 1970.
Before then, pesticides were found to be causing reproductive failure in the peregrines, by thinning the birds’ egg shells.
“We knew DDT was no longer an issue and based on field observations, we wondered whether changes in climate were responsible for high mortality in recent years,” Franke said.
In addition to deaths caused by rainfall, the study also found many chicks were dying from starvation, despite being spared by the rain.
Researchers call the study’s findings an important example of the indirect effects of climate change, highlighting the need for ongoing monitoring.