Fish eagle is a fascinating raptor
I was just a boy canoeing the Crow Wing River when I witnessed for the first time in my life the dive of an osprey. The great bird had apparently just finished its dive, for it was the loud splash that alerted me. I watched in amazement as a large and obviously wet bird emerge from the river like some gigantic mayfly having just hatched from the riverbed. The bird flew straight up and began to hover effortlessly 30 or so feet above the water.
A few seconds later the osprey abruptly fell from the sky as if forgetting to flap its wings. In an instant, the bird entered the water in a thunderous splash, breast and feet first, disappearing momentarily in its own wake, and reemerge in a spray of beating wings while clutching tightly in its talons a struggling fish.
In wonderment, I watched as the fish hawk worked to control and subdue its squirming prey as it continued its flight over the tall trees alongside the riverbank. The bird, grasping the fish, positioned the fish headfirst and parallel to its own body. I was struck by the method it carried its fish. One foot was ahead of the other, holding securely its meal. The image of the dangling fish suspended below the osprey was not unlike that of a sailboat's keel.
The osprey is a fascinating bird of prey. Often called "fish hawk" or "fish eagle," these latter names are aptly assigned. Indeed, the osprey's principle prey is fish. It is no wonder that this elegant raptor makes its home throughout Minnesota's thousands of lakes, wetlands and rivers.
Well suited to a fishing lifestyle, ospreys are the only species of raptor with a "reversible" outer toe. This unique adaptation allows the osprey to clutch its prey with two toes in the front and two in the back. Other characteristics include nostrils that close shut when it dives underwater, in addition to sharp projections underneath the toes and rear-facing scales on its talons, which, together -the projections and scales -enable ospreys to better hold their slippery and flopping fish-prey.
Ospreys are fairly easy to identify. With a wingspan of up to 6 feet and a body length from beak to tail at about 2 feet, the bird is sizable amongst hawks, falcons and eagles. In flight, ospreys are sometimes confused with gulls and eagles, but the manner in which ospreys fly and hold their wings will often be enough for proper identification. A distinctive kink at the elbows gives the wings a kind of swept-back appearance in the shape of a subtle looking "M."
If you're lucky enough to observe an osprey doing what they do best, catching fish, then you've seen what really sets them apart from other fishing birds. Whereas kingfishers dive and skewer fish with dagger-like beaks, and brown pelicans dive in stunning headfirst displays to scoop fishes inside their homely beak-pouches, and loons slip quietly below the water's surface to overtake their quarry with beak and speed, the osprey dives with open talons to capture its prey. An osprey, as many observers have come to know, rarely misses.
The name "osprey" has an interesting origin. It is thought to be derived from the Latin word ossifrage, ossifraga, or ossifragus, meaning, "bone breaker." Another explanation for the English name - osprey - is believed to have come from the old French "ospreit," which means, in Latin, "avis praedae" or "bird of prey."
Ospreys' plumage coloration is classic amongst the animal kingdom. Colored white below and dark above, this color pattern is often referred to as "disruptive coloration." Many other species of fishes, amphibians, birds, and mammals exhibit similarly contrasting bellies and dorsums. The white-footed mouse, northern pike, and leopard frog are just a few other examples.
The reason for this pattern is simple. Whether the species is the hunted or the hunter, being able to escape detection is vital to its survival. And ospreys are no different. While hovering above a lake's surface, the bird's white belly blends into the sky above, thus making it difficult for fish and other quarry to see the raptor. Being less visible is key to an osprey's fishing success.
Nests are made out of sticks and can become quite large over the years. Nests usually built in the tops of trees, especially coniferous trees. Ospreys will also use artificial nesting platforms placed on highline poles. Recognizing ospreys' willingness to use platforms for nesting, wildlife and power company managers have had positive results by constructing such structures as either stand-alones or on top of existing highline poles and towers. Several of these artificial nesting platforms can be observed on various power line structures in the Bemidji area.
The remarkable osprey is a bird worth watching. Striking plumage, interesting vocalizations, unique hunting style, life-long pair bonding and devoted parenting are just some of the many fascinating aspects of this bird of prey. Closely related to hawks, eagles and falcons, the osprey is nonetheless a different sort of raptor to observe as you get out and enjoy the great outdoors.
Blane Klemek is the Bemidji area assistant wildlife manager, DNR Division of Fish & Wildlife. He can be reached at firstname.lastname@example.org