The Fall and Recovery of Osprey Populations in Ontario
~ Elspeth MacLachlan and Margaret Hough
Anyone with a cottage along the South Shore of Eagle Lake and an interest in birds has
undoubtedly seen Osprey soaring high above the water.This bird of prey is spectacular to
watch. They hover high above the water looking for fish close to the surface of the water and
then dive from up to 40 meters above the surface, plunging into the water to successfully
snag the fish. Rising from the water with a fish gripped in its talons, it frequently pauses to
shake the water from its plumage and rearrange the fish with head pointed forward. Osprey
have barbed talons allowing them to firmly hold their prey. However, Osprey can drown if
the fish they have caught is too heavy since the barbs prevent the release of the fish. Unlike
the bald eagle, the osprey rarely eats dead fish and thus is a tireless hunter, barely consuming
its catch before going hunting for more.
Osprey are one of the most widely distributed birds inhabiting most parts of the world except
the Polar regions. At least one third of the worlds breeding Osprey are found in Canada.
Their large stick nests are usually build at the top of dead trees, close to the water although,
since these birds are adaptable and tolerant of humans, they will also nest on man-made
structures including hydro poles, microwave towers and duck blinds.In Southern Ontario, an
Osprey’s clutch is typically three eggs with the male providing virtually all the food for the
family while the female remains on the nest. Osprey that breed in Ontario migrate up to
8,000 km to wintering areas in Central America, Peru and Argentina. They usually spend
their first two years of life in Central or South America before returning to Ontario to breed,
normally within 50 km of their natal site.
Due to pesticide use, especially DDT, these magnificent birds were almost extinct by the early
1970s. When DDT was first used as a pesticide in 1945, its effects on wildlife were unknown.
Through groundwater runoff and air pollution, DDT and other pesticides made their way
into lakes and rivers, first affecting species living in the water, then the animals feeding on
aquatic species. The osprey was one of the first species to show the effects of DDT
contamination, through egg shell thinning, lowered reproductive capabilities, and even direct
mortality. Because of the efforts of many environmental activists, including Rachel Carson,
the author of Silent Spring, DDT was banned by 1972. Luckily, successful human
intervention programs were able to restore the population of osprey in the area, showing that
human intervention can effectively help endangered populations recover.