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Archive for August 1st, 2009

ospreynest

I’ve been down by the Iroquois lock a half-dozen times since the spring, but it was only on a visit this week that I noticed a nest. A LARGE nest, in an unexpected place!

ospreynest2

On the arm of a crane set beside the lock is an Ospreys’ nest. Ospreys (Pandion haliaetus) build their nests of dry branches, interwoven with other materials such as strips of old cloth, plastic, and seaweed. The average Osprey nest is 30 to 60 cm deep and about a meter across. Usually nests are placed high up in a tree beside water, but Ospreys will also use a utility post or artificial platform. This pair have found a unique support. A crane! The crane is only used for emergencies, and a birder I met at the lock lookout told me that it has never been used since the lock was opened, so the nest is safe.

osprey1

Two birds could be seen in the nest, a female and her chick. The female usually does most of the incubating and tends the young chick, while the male is the sole hunter for the family. He feeds the female while she incubates and once the chick hatches, he brings food for both the chick and his mate. Ospreys are fish specialists (sometimes called fish hawks) and have feet especially equipped for grasping slippery fish. They are the only raptors that can turn one front talon backwards, and the pads on the soles of the feet have spines. An Osprey catches fish by diving from the sky with its claws stretched forward and splashing into the water to snatch its prey. This pair may have been attracted to this location because fish are concentrated by the control dam south of the lock.

ospreydadflying

Here comes Dad, making a delivery to the nest. He passes the food to Mom, who feeds the chick.

ospreydadatnest

Raptors such as Ospreys are relatively long-lived birds and feed at the top of the food chain. This makes them more susceptible to poisoning from pollutants and pesticides than more short-lived, plant-eating birds. In the 1950s and 60s, DDT had a catastrophic effect on many raptors, including Osprey. Since DDT was banned, populations have been rebounding.
Osprey pairs often share the same nest year after year, and may repair the nest late in the summer for use the following year. It will be interesting to see if this pair returns next year.

osprey2

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