March 06, 2014

Ice on lakes forcing eagles into new areas

As published in the Georgetown Independent & Free Press

Recent bald eagle sightings in the Georgetown area are likely the result of an unusually cold winter, with frozen lakes forcing the raptors to adjust their hunting patterns, according to specialists at Credit Valley Conservation (CVC).

“They are opportunists,” said Christina Kovacs, a technician with the Significant Wildlife Program at CVC. “They like fish and waterfowl, but they will take anything they can get.”

The waters of Silver Creek and the Credit River can provide food for eagles, and the forested areas of the Niagara Escarpment and the Credit watershed provide other opportunities, since they will feed on the carcasses of larger animals such as deer, said Kovacs.

“These are natural corridors that help with migration, and will benefit the species in the long term,” said Scott Sampson, Manager of CVC’s Natural Heritage Program.

This is Southern Ontario’s coldest winter in 20 years, and most lakes – even Lake Erie  and Lake Huron – are largely covered with ice. Lake Ontario has open water, but heavy urban development on the north shore makes for poor eagle habitat, said Sampson.

While climate change is believed to be affecting some vegetation and wildlife territories, there is no definite link with the eagle activity, he said.

Bald eagles have been a rare sight in Southern Ontario since the mid-1900s. There is no evidence of nesting sites in Halton Hills, but there have been frequent sightings at Island Lake next to Orangeville and the Luther Marsh near Arthur.

“The number of reports is increasing,” said Sampson, noting that the first hatching of eagle chicks in decades took place at Cootes Paradise near Hamilton last year. “They are making a comeback since we got rid of DDT.”

Eagles were once plentiful near Lake Ontario, but human settlement destroyed much of their habitat, and they were hunted as a dangerous predator. Protective Ontario legislation in 1890, and the American Bald Eagle Act in 1940, helped boost their population.

It dropped again to near extinction in the 1960s with the use of pesticides such as DDT, which weakens the egg shells. The Bald Eagle was declared a provincially Endangered Species in 1973. That status was upgraded to a Species of Special Concern, in 2006 for Northern Ontario, and in 2009 for Southern Ontario.

Raptors such as the eagle and osprey prefer to build their large nests on tall, old-growth trees overlooking water, but are often willing to use poles and platforms erected for them by conservation staff.