Study Links Precipitation and Changing Arctic Temperatures to Decline in Peregrine Population

A latest study says that increase in the frequency of heavy rains is posing a threat to the population of the young peregrine falcons in Canada's Arctic.

The study conducted by researchers at the University of Alberta, reveals that extensive rainfall brought on by warmer summer temperatures is a big threat to the Peregrines falcons in the Canadian Arctic. The species faced a similar threat before pesticides like DDT were banned in Canada. This is the first study to highlight the strong correlation between rainfall and the survival of the falcons in Canada.

A nest box experiment conducted between 2008-2010 in a breeding area near Rankin Inlet, Nunavut, has confirmed that the gradual alterations in the temperatures of the Arctic as well as precipitations are the main culprits for the long term decline in the falcon's annual productivity. Peregrine falcon is one of the top predators in the Arctic.

The study co-authored by U of A researchers Alastair Franke and Alexandre Anctil of the Universite du Quebec, also incorporated the historical data and breeding successes to evaluate whether the recent changes in the precipitation system can explain the decline in falcon productivity. They noticed that the extensive rainfall was solely responsible for more than one third of the recorded nestling mortalities. Heavy rainstorm greatly affected the juvenile falcons.  The researchers monitored the falcon nests using motion sensitive cameras.

"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," Franke said.

It has been an ongoing decline for the past 30 years, even at times when the concentration of the pesticides was too low to cause any decline, so it had to be climatic factors that triggered high mortalities. Apart from rainfall, the researchers also observed that chicks also died due to starvation.

"We were surprised to find that a considerable number of nestlings raised in nest boxes later died of starvation despite having been spared from the direct effects of rain," said Franke. To explore this link the team has launched a food supplementation study.

Franke concludes saying, "They have improved our understanding of the direct effects of long-term changes in weather patterns and have identified the potential importance of indirect effects."

The study findings were published in Oecologia.