Over the twenty or more years that we have been walking at Mill Lake, the same pair of bald eagles have been nesting in a tall tree near the water’s edge.
After going off to feast on spawning salmon in the fall, the eagles return to their home territory late in the year. They nest about the end of February, and the eggs hatch about a month later. Fifty percent of the time they produce a single eaglet, a quarter of the time they produce two or more, and a quarter of the time they produce nothing—the eggs are broken, crows eat the babies, or some other mischance occurs. We passed under the nest at Mill Lake one year shortly after the baby, full-grown except for its flight feathers, had fallen from the nest. A witness said it had bounced off branches on the way down and broken its neck.
The babies start flying around mid-summer and go off in the fall for the easy meals provided by dead and dying salmon. They never return to their nesting grounds, and start mating and producing babies of their own when their heads and tails turn white, about age five. Eagles mate for life. A half-century ago, their numbers had declined, but their numbers rebounded dramatically after governments banned the pesticide DDT, which made egg shells too fragile.
Golden eagles (about the same size but with different colouring) live in the country and mostly eat small rodents and mammals, but bald eagles prefer to live near a pond or stream or even the ocean and eat fish. But they are opportunity hunters. They will eat goslings, ducklings, coots, crows, rabbits, rats, mice, cats and just about anything else that is available. We once found an eaten-out turtle shell under the nest at Mill Lake. And a friend of mine tells me that eagles flock to the city dump to eat garbage.
Eagles are territorial. The walk around Mill Lake is a little over a mile, and the local eagle pair claim the whole lake as their own. They chase off any other eagles (including their own grown offspring) who try to invade their territory.
Eagles are graceful hunters. They perch along the lake or soar above it, ignoring the crows that frequently dive bomb them. When they spot a fish near the surface of the water, they swoop down silently, their talons gently touch the water, and they soar off with a fish. They are apparently successful about ten percent of the time.
Bald eagles are not the only fishers at Mill Lake. There are also some osprey who nest in a ravine about a quarter mile away. Osprey are a little smaller and whiter than eagles. While the eagles gracefully snatch fish from the surface of the water, osprey smack full speed into the water and go down under the surface after the fish. Seeing them, you would think they would break every bone in their bodies when they hit the water. Or perhaps the violence of the collision with the water stuns the fish. If the osprey catch a fish in our eagles’ lake, the eagles often chase them back to their nest and steal the fish.
Cormorants are sea birds that also fish in the lake. Thin and gangly, they are often seen standing on logs in the middle of the lake, with their wings spread to dry, like a line of old hags. They swim low in the water like loons, but are somewhat bigger. They are excellent swimmers and go under water to chase down the fish. We once saw a cormorant catch a fish that was too big to swallow. After several attempts, it spit the fish out, and another cormorant tried. Suddenly both cormorants abandoned the fish, diving under the water in opposite directions. The eagle swooped down and picked the fish off the surface of the water.
There is also a blue heron that visits the lake to fish. Its fishing technique is uninspiring. It stands very still by the reeds at the end of the lake and snatches any fish, turtle or frog that comes close. It is not seen in the spring. It probably nests with a couple of hundred other herons at a rookery a few miles away.