Chicks are freezing and drowning in their nests
By Summit Voice
FRISCO — Canadian wildlife biologists say they’ve found unequivocal evidence that gradual changes in Arctic temperature and precipitation are responsible for a long-term decline in reproduction for the peregrine, a top predator in the Arctic.
Specifically, increases in the frequency of heavy rains resulting from warmer summer temperatures is killing peregrine falcon chicks in their nests.
“The nestlings died from hypothermia and in some cases from drowning in their flooded nests. Without constant parental care, they are most vulnerable to cold and wet conditions in the first three weeks of life,” said University of Alberta researcher Alastair Franke.
The threat to the species is higher than any time since before pesticides such as DDT were banned from use in Canada in 1970, according to the researchers, who used historical weather data and measures of breeding success dating back to 1980.
From 2008 to 2010, the scientists conducted a nestbox experiment in a dense population of peregrines breeding near Rankin Inlet in Nunavut on the shores of the Hudson Bay. Falcon nests were monitored using motion-sensitive cameras, and images confirmed that more than one-third of the chick deaths recorded were caused by rain, whether they were raised in nestboxes or on natural ledges.
Their findings helped explain the ongoing 30-year decline in peregrine falcon populations, even as pesticides in the environment declined.
“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.
Besides deaths attributed to rainfall, the study also discovered additional fallout for chicks: starvation
“We were surprised to find that a considerable number of nestlings raised in nestboxes later died of starvation despite having been spared from the direct effects of rain,” Franke said.
The findings have improved the understanding of the direct effects of long-term changes in weather patterns and have identified the potential importance of indirect effects, he explained.