Again this year the Ospreys are back at their nest site in the swamp by the Nelson Road at Crane Lake. Each year they return right about the same time: April 15th. This year was no exception, despite the late winter-like weather. Birds seem to keep a pretty tight schedule as far as when they return north from their wintering grounds. Ospreys winter as far south as South America, although some Ospreys are year round residents in places like Florida. And Ospreys occur on every continent in the world except Antarctica.
Ospreys are fish eaters and unlike the Bald Eagle they insist on only fresh fish, they don’t eat carrion or dead fish like Eagles. When Osprey are airborne, a conspicuous crook to their wings and black wrist marks are good field identifiers. Their flight looks similar to a Gull’s with the way they hold their wings. Except when migrating, Ospreys flap their wings more than they soar. Their wingbeats are slow and deep. When fishing, Ospreys hover 50 to 150 feet above the water and then plunge to the water for their fish sometimes going completely under the water. They always use their feet and their strong talons to grab the fish. Their beaks are only used to rip up their prey and is not used for capturing fish. The eyesight of a raptor is way too valuable for them to ever use their beak in a manner that might endanger their eyes. Barbed pads on the soles of their feet help them to grip slippery fish. When an Osprey takes a large fish to their nest, they carry the fish headfirst to make it as aerodynamic as possible
This year it looks like they have one chick in the nest. Since I have been watching this particular nest site, they have had one successful nesting that occured 3 years ago. Two years ago, in 2007, I think the nesting may have failed due to cold spring weather. The adult was sitting on the nest in May, but then abandoned the nest after a severe cold front came through that lasted a couple weeks. Then last year in 2008, a chick was hatched, but something happened to the chick somewhere around July 12th. Perhaps a Great-horned Owl or even a Bald Eagle may have predated the chick.
This year it is looking good. Both parents are tending the young chick and keeping a vigilant watch for predators. The other day I was lucky to catch one of the adults bringing a fish in to the youngster and captured it on video!
Ospreys and Bald Eagles compete in a unique way in the Voyageur Country of northern Minnesota. Both birds of prey were severely affected by the toxic affects of DDT before it was banned in 1972. Since that time both species have rebounded as their populations have increased. The nests of both birds are quite similar, but they are also different. Ospreys build their large nests on the very top of trees that are usually dead. They’re often added to and used year after year. They even favor things like electrical poles. Although the power company doesn’t care for that and as a result they have constructed nesting platforms close to those sites for the Ospreys to use. In many places south of here you can see where Ospreys are nesting on artificial platforms. Bald Eagles build a similarly huge nest, but their nest is usually located about 1/3 of the way down the tree. Eagles seem to favor big White Pines so they can navigate through the branches with their huge wing spans.
In nature things aren’t always easy for birds that eat the same things. Bald Eagles take advantage of Ospreys and many times you will see them battling for a fish that the Osprey has just caught. Bald Eagles will also steal young chicks from their nests. Last fall I heard that two Eagles were harassing an Osprey until the bird was exhausted, then they killed the Osprey mid air! Unfortunately in nature all is not rosy and it is well known that in an area where Bald Eagle populations are going up, Osprey populations tend to go down.
For now all is fine at the Crane Lake nest site and the chick is eating well.