Osprey 2025

(C) Bob Reiter

The Osprey (Pandion haliaetus) is a large fish-eating raptor with a wingspan close to six feet. Its distinctive plumage is dark brown above and bright white below with dark carpal patches and its head is white sporting a dark eye line. Ospreys often fly with bent wings leading to the characteristic M-shaped silhouette. Ospreys are circumpolar and breed on all continents except Antarctica. They are considered “complete” migrants with nearly the entire U.S. population migrating to Central and South America where they overwinter along rivers, lakes and coastal areas.

Historically, the Osprey built their bulky stick nest atop trees, rocky cliffs, and promontories, but have shifted to nesting on artificial structures such as radio and cell phone towers with 90-95% of nests in some regions now on artificial structures. In Pennsylvania, Ospreys return in late-March to early April to rebuild their nest and lay 2-4 eggs. Following incubation and chick rearing, nestlings fledge in July, spending 30-40 days practicing their fishing skills before undertaking their southern migration in September. Yearlings will spend two winters in the tropics before returning to the breeding grounds as two-year-olds.

(C) Jeanette Green

Populations in some areas of the U.S. saw large declines in the 1950s through 1970s due predominantly to DDT which caused egg-shell thinning. This led to Ospreys being listed as threatened or endangered in many eastern U.S. states including Pennsylvania. Ospreys were listed as extirpated in Pennsylvania in 1979 and as recently as 1986, only one pair was known to be nesting.  Following the banning of DDT in the 1970s and successful reintroductions, the Osprey showed a tenfold increase in the number of nests recorded between the first Breeding Bird Atlas with nine and second atlas with confirmed nesting in 90 blocks. The Osprey was delisted in Pennsylvania in 2017.  (David Barber)