Heavy rain in the Canadian Arctic is killing peregrine falcon chicks and could contribute to a long-term decline in reproductive success in the population, a new study has found.
The study, conducted by researchers at the University of Alberta and the Université du Québec, found prolonged, heavy rains in the Arctic are causing peregrine chicks to drown or die of hypothermia. Researchers monitored the progress of 14 broods of peregrine falcons on Hudson Bay in Nunavut, Canada, and found that 38 percent of the chicks that died did so as a result of the effects of rainfall.
“They’re completely covered in fluffy down,” study co-author Alastair Franke said of the chicks. “That down gets wet very quickly.”
Usually, a mother peregrine will cover her chicks with her wings when it rains, shielding them from getting wet. But the study found more frequent rain spells are forcing some mother peregrines to give up and leave their chicks exposed to the rain. In one case, a mother who left her chicks in the rain for several hours and returned to find them visibly weakened killed both of them — the first case of infanticide ever recorded in wild peregrine falcons.
The study also did a three-year analysis of 34 nestlings raised in nest boxes, which provided cover from the elements, and and 117 nestlings raised on natural ledges. They found that the nest boxes helped in alleviating nestling mortality from drowning or hypothermia, but that some chicks in nest boxes still died of starvation — prompting worries that the Arctic rain was also having a negative impact on the falcons’ prey, such as lemmings and ground squirrels. The researchers are now conducting another study on prey species to see how they respond to increasing heavy rains.
According to the study, there’s been an uptick in the number of days with heavy rainfall in the Canadian Arctic from 1981 to 2010, a trend that follows increasing temperatures in the region and that’s consistent with predictions of climate change’s effect on precipitation. According to the study, this change in precipitation patterns could pose a risk to peregrines that hasn’t been seen since DDT caused the raptor’s population to collapse in 1970.
“As big a problem as DDT was, it was relatively easy to solve,” Franke said. “All we had to do was ban DDT. Reversing the inertia associated with climate change is far more difficult.”
The study is the first to link rainfall to the survival of Canadian wild birds, but it isn’t the first to show the risk climate change poses to birds around the world. Earlier this year, a report from the National Wildlife Federation outlined the effect climate change is already having on birds, and how birds, especially migratory ones, will likely be threatened in the future.
As the climate warms and spring begins earlier — or falls back into winter temperatures soon after beginning — there’s more risk that migratory birds won’t arrive at their breeding grounds during peak bud burst and insect outbreak. And already, Arctic terns in the U.S. have declined 40 percent over the last 10 years — in Maine, Arctic tern chicks are starving to death, partly because warming oceans are forcing the fish their parents depend on for food to move to colder waters.