Connecticut Audubon Bird Finder for April 11: Osprey
Written by Frank Gallo, director of Connecticut Audubon Society’s Coastal Center at Milford Point
Where to find it: The Ospreys have returned to their nest in the Wheeler Marsh behind Connecticut Audubon’s Coastal Center at Milford Point. Like clockwork, the male returns between the 19th and 24th of March, with the female usually arriving a couple of days after. Rarely, as is the case this year, the pair arrive from the wintering grounds on the same date. This year, it was Monday, March 24. Most Ospreys from the northeastern United States winter in northern South America, with other Osprey populations wintering from the southern U.S. through Mexico and Central America. Males return early to establish territories before the arrival of the females.
What it looks like: Ospreys are fairly large, long-lived raptors, dark brown above and white below, with a body length of 22 inches, a wingspan of up to 70 inches, and can live 25 years. They have a distinct white forehead patch, and hold their wings crooked back in a shallow M-shape when in flight. Sexes are similar in size, but the female has more distinct breast streaking than the male, which can be completely white-chested.
Their diet is 99 percent fish, and they possess modified toe pads, called spicules, that allow them to grasp and hold their slippery prey. They are unique among hawks in having a reversible outer toe, like owls, that allows them to secure fish with two toes in front and two behind; they position the fish head first when in flight to minimize wind resistance.
Nearly as soon as the female arrives, the male brings her an offering of a fish. Once accepted, copulation soon follows, and the male sets to bringing sticks to the female, who rebuilds the nest. Over the next couple of weeks the female will lay eggs, usually a clutch of four, 1-3 days apart; incubation begins with the first egg and takes 36-40 days; the eggs hatch asynchronously, each hatching in the order laid. This gives a distinct advantage to the older chicks in years with meager food supplies. If the weather is bad, all may not hatch. Generally, two or three babies fledge annually. The pair at the Coastal Center is very experienced and capable of raising all four young when food supplies are plentiful!
How to find it: Ospreys frequent areas with plentiful numbers of fish, especially coastal marshes and bays and may be found inland along large rivers, lakes, and wooded swamps. Their large size, dark brown (looks black) and white pattern, and gleaming white forehead, combined with a habit of hovering in place while they hunt, make them easy to spot at great distances.
What if they are not there: Ospreys can be found in most coastal marshes and larger bodies of water throughout the state from late March through August, and migrants often stay into October. Their stick nests are quite conspicuous and are often on poles in the marsh erected specifically for them. If you can’t find one in the wild, the Coastal Center has a camera trained on the Osprey nest that can be viewed on screens within the center, and on line here.
Conservation Status: Ospreys were greatly affected by the pesticide DDT which caused egg-shell thinning and reproductive failure, and eventually led to their being placed on the Endangered Species List. DDT was banned in 1972, and tremendous efforts were made to return the ospreys to their former nesting grounds, including the erecting of nest poles in suitable habitat throughout their former range. In 1974, Ospreys had reached a low of seven active nests in Connecticut, but slowly they have recovered, and are no longer on the endangered list. They are now a fairly common nesting species along the Connecticut coast and on some major rivers and inland lakes. They can still ingest DDT on their wintering grounds, so continued careful monitoring is important.
In celebration of the Ospreys’ return, the Coastal Center is having its annual Return of the Osprey Party fundraiser on Saturday, April 12, at 5:30 pm at the Center. It’s a chance to meet old friends and new; there is live music, fine wines, hors d’oeuvres, wonderful silent auction and raffle items, and good company.
We hope you can join us!
Tickets are $40/ person, $75/ couple. Call Louise to register at 203-878-7440 x 502 or download a registration form from our web page.
Connecticut Audubon Bird Finder is edited by Tom Andersen.
Photo: Screen shot of one of the Milford Point Ospreys taken from the OspreyCam on Wednesday, April 9, 2014.