Wildlife in the Credit River Watershed
This is part-three, in our four-part wildlife spotlight series where we’re sharing the exciting news that over the past few years our staff have spotted, or have received reports of four species in the Credit River Watershed that had no previously confirmed records of presence or breeding.
In each edition of this series, we introduce one of the four species so you can learn more about them and their roles within the watershed ecosystem. This week, we’re highlighting the bald eagle.
Species Spotlight: Bald Eagle
Known for its majestic appearance and intimidating demeanour, the bald eagle (Haliaeetus leucocephalus) is one of the largest birds in North America.
Despite their name, bald eagles are not bald. Instead, their white-feathered heads shine in contrast to their dark-brown body and wings.
They can grow up to 71 to 96 centimetres long and their wingspan can reach up to two metres. They weigh between 6.6 to 13.8 pounds, with females typically larger than the males, a phenomenon referred to as sexual dimorphism.
Despite their power and size, bald eagles have surprisingly soft calls. They call in a series of high-pitched whistling or piping notes. Often when bald eagles are shown on television or movies, audio engineers will use the call of a red-tailed hawk because it sounds more dramatic.
Where They Fly
Bald eagles can be found throughout most of North America.
In the Credit River Watershed, bald eagles are most often sighted near Lake Ontario or the Credit River because of their affinity for water.
Some bald eagles are resident birds, meaning they stay in the same general area for the entire year and some are migratory. Migratory bald eagles in Ontario fly south during fall migration and return to breeding grounds in Ontario during spring migration. September and October can be a good time to head to our parks for birdwatching if you want to try your luck at spotting migratory bald eagles.
What They Eat
Bald eagles often skip the tedious act of fishing or hunting. Instead, they are often seen going after other birds’ fresh catches. Bald eagles harass birds, like ospreys, in mid-flight, forcing them to drop their prey, which the eagles then steal.
However, they hunt cooperatively too, with one bald eagle cornering prey towards the others in a group.
Bald eagles prefer a diet of mainly fish, but as opportunistic birds, will eat a wide variety of foods including waterfowl, deer, small mammals and carrion (deceased animals). Sightings of them rummaging through discarded food at landfills have also been recorded.
Reproducing Populations
Bald eagles can live to over 30 years old, with the oldest recorded bald eagle in the wild being at least 38 years old.
Bald eagles nest in trees, reusing nests from year to year. Nests are usually one to two metres wide and nearly one metre tall, making them some of the largest nests built among all bird species.
Both males and females build the nest, but females will place most of the materials. Nests are made up of woven together sticks, softer material such as grass, moss or cornstalks and the inside is lined with lichen or other fine woody material, then with downy feathers and sometimes soft plants on top.
Females typically lay one to three eggs, incubating for approximately 35 days before they hatch.
Juvenile bald eagles are dark brown and take around five years to fully mature. This is when they get their adult plumage with fully white head and tail feathers. For their first four years, they explore vast areas travelling far and wide, sometimes flying hundreds of kilometres per day.
Decline of Bald Eagles Leads to Protections
North American populations, once large, dwindled in the mid-to-late 1900s due to pesticide-induced reproductive issues and hunting. The southern Ontario population was almost extirpated, reduced to about three to eight pairs in the 1970s, with almost no successful reproduction.
By 1973 action was taken. The bald eagle was one of the first species listed under Ontario’s original Endangered Species Act in 1973. After, an increase in bald eagle populations in Ontario was seen with the North American-wide prohibition on the use of DDT. Other recovery initiatives in Ontario involve releasing bald eagle nestlings in the southwest, educating the public, conducting contaminant sampling and protecting habitats to maintain their populations. Bald eagles continue to face threats, including collisions with motor vehicles and stationary structures and development-related destruction of shoreline nesting, perching, roosting and foraging habitats. These protections and restoration of forested and riparian habitats have helped increase populations.
Bald Eagles in the Credit River Watershed
As we do not monitor bald eagles specifically, we do not have formal data on their whereabouts in the Credit River Watershed. However, nesting has been documented recently close to Port Credit and also confirmed in Hamilton, Toronto, Oakville and several other locations around the Greater Toronto Area.
Reason for Returning
Actions that may have increased populations include:
- In 1985, Canada, banned the pesticide DDT.
- Habitat restoration and improved water quality.
- Protection of greenspaces, forests and wetlands.
- Protection under the Endangered Species Act in Ontario.
Populations increased and stayed stable from these conservation efforts to a point that they were removed from the Ontario Endangered Species Act in 2023.
Protect, Restore and Enhance
Birding is a popular activity in our parks. Connect with nature and plan a day of birding at our parks.
Help report animals and plants in the Credit River Watershed through community science! Submit photo observations to eBird or iNaturalist.
Follow us on Instagram, Facebook and X for more fun nature and wildlife facts.
By Sarah Lebret, Associate, Marketing and Communications.