Over the past 30 years, scientists have seen peregrine populations in the Canadian Arctic undergo an ongoing decline, even though pesticide residues were known to be too low to cause reproductive failure. ‘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,’ said one author of the new study, Alastair Franke, of the University of Alberta.
The researchers used historical weather data and measures of breeding success dating back to 1980 to uncover evidence that changes in rainfall patterns in recent years have had a large influence on the overall decline in reproductive success. In order to back this evidence up, they also conducted a nest-box experiment between 2008 and 2010 in a dense population of peregrines breeding near Rankin Inlet in Nunavut on the shores of the Hudson Bay.
Images from motion-sensitive cameras used to monitor nests confirmed that more than a third of the chick deaths recorded were caused by rain, whether they were raised in nest boxes or on natural ledges. ‘The nestlings died from hypothermia and in some cases from drowning in their flooded nests,’ Francke said. ‘Without constant parental care, they are most vulnerable to cold and wet conditions in the first three weeks of life.’
This story was published in the February 2014 edition of Geographical Magazine