St. Lawrence Islands National Park of Canada

Mighty but small

The bald eagle soars again over the St. Lawrence, but populations are still low

Bald Eagles reach sexual maturity at four to five years, the same time as they acquire a full white head. It’s at this time that they look for mates and nesting territory. Only one pair has successfully nested on the St. Lawrence since 1999 – the first eagles to nest here in more than 60 years.
© Parks Canada

They’re powerful birds and impressive to see, but bald eagles are still a rare sight along the upper St. Lawrence River.

Since 1999, only one pair of eagles has maintained a nest in the 1000 islands. However, considering the bald eagle was completely absent from the area for more than 60 years, a healthy nest is a good sign.

Unfortunately, the bald eagle’s overall recovery from the era of DDT has been slow. The St. Lawrence River bald eagle nest is part of a study to determine the reason why.

The normal lifespan of a bald eagle in the wild is 25 to 30 years but there is evidence that Ontario’s eagles aren’t surviving much past 15. It’s been suggested that the eagles are dying young from lead and mercury poisoning.

Studies have shown that the eagle chicks hatched on the St. Lawrence River don’t have high levels of heavy metal contamination at birth. The health risk, therefore, develops as they grow and must be acquired from their environment through the food they eat.

For a bird that has the entire continent to roam, it’s difficult to know where the food contamination is coming from. That’s what the bald eagle tracking project, led by Bird Studies Canada, is attempting to determine. Young eaglets are fitted with satellite transmitters, which are purchased through donations from local organizations and community members, and followed for up to five years.

So far, the project has shown, as predicted, that most young bald eagles like to wander across eastern North America. Regal, the St. Lawrence eagle fitted with a transmitter last June, was an exception to that rule. Until her transmitter failed in January (for unknown reasons), Regal stuck fairly close to home. That may be because her nest on the St. Lawrence is in a great spot for wintering eagles, who gather at open water for access to fish.

Regal, one of three eagles hatched on the St. Lawrence River last summer, wore a backpack transmitter to track her movements. Researchers hope to learn more about eagle migration and feeding grounds as part of an international effort to better protect this majestic species.
© Parks Canada / Pete Nye

Those fish and the lead some of them carry could be one of the biggest eagle killers in Ontario. Lead contamination can come from any river or lake where people go fishing. One lead fishing sinker, swallowed by a fish and then eaten by an eagle, can kill the eagle in a matter of weeks. It sounds extreme, but it’s true. The good news is that this is a problem that’s easy to solve – there are plenty of sinkers made of  non-toxic metals such as tin, bismuth, tungsten, and steel.

Mercury poisoning, on the other hand, is more difficult to control. Most mercury contamination comes out of the atmosphere, put there by industry.

The data gathered from following the St. Lawrence eaglets will contribute to the protection of the eagles and their habitat – the main goal of the international St. Lawrence Bald Eagle Working Group, which is made up of government and non-government organizations in Ontario and New York. Soon, it is hoped, there will be many more nests of this mighty eagle along the St. Lawrence River.

For more information on SLINP’s contributions to the Eagle Monitoring Project, call 613-923-5261.

As long as their transmitters continue to function properly, the St. Lawrence eagles can be followed year-round through the “Eagle Tracker” on the Bird Studies Canada website at www.bsc-eoc.org. One or two new eaglets from the St. Lawrence nest will be fitted with transmitters early this summer.