By Patrick McShea, Division of Education at Carnegie Museum of Natural History

Last summer’s Bassmaster Classic established fish-catching as a spectator sport in Pittsburgh. Post-tournament estimates of 100,000 spectators lining bridges and riverside vantage points might well result in another major tournament being held on our rivers, but not at least until the summer of 2008.

Anyone looking for a more immediate opportunity to observe out-of-town experts testing their fishing skills on waters in western Pennsylvania might want to invest in a pair of binoculars.

Beginning in late September and continuing throughout October, the great flow of the Allegheny, Monongahela, and Ohio mirrors an overhead trickle of large birds known colloquially as fish hawks and more properly as Ospreys.

From summer territories as close to Pittsburgh as Moraine State Park and as distant as Hudson Bay, the nearly eagle-sized birds follow the water, singly or in pairs, to a winter range that stretches from the Gulf Coast deep into the South American Continent.

This intermittent procession, which has occurred for at least the past dozen years, is a revival of a centuries old natural cycle. On a national level, Osprey populations plummeted during the middle decades of the Twentieth Century as residues of DDT and other related pesticides in aquatic food chains interfered with egg shell formation and consequently dramatically reduced the birds’ reproductive rate.

The species’ rebound in recent years is attributable not only to diminished presence of the harmful chemicals, but also to the successful efforts by various government and private agencies all over North America to re-introduce the birds into suitable habitat.

Bridge bound commuters who aren’t familiar with an Osprey’s crooked wing silhouette or the distinctive patterning of its white underside aren’t likely to notice a passing migrant when it’s 300 feet above them and intent on covering ground.

Circumstances can be quite different, however, when a hungry Osprey descends to circle the water at something closer to treetop height. When a gliding Osprey detects a potential meal it uses rapid wing beats to effect a seemingly awkward hover. After a few seconds in this stationary position the predator either resumes its reconnaissance maneuvers or folds its wings and plunges feet-first toward the finned prey.

The graceless splash that concludes such dives offers little clue about the effort’s success, for, unlike the film footage most often selected for nature documentaries, misses are as common as hits. A floating bird’s effort to regain flight, however, is a reliable predictor. Watch an Osprey struggling mightily to free itself from the river surface, and you’re likely to see a fish follow the bird into the air.

The slippery scaled cargo, secured by inch-long curved talons, is carried face-forward to a secluded dining perch, but only after the Osprey trims its traveling weight with a dog-like shake that sends a shower of water drops back to the river.

Areas of shallow water near creek mouths and islands are favored Osprey fishing spots, and at this time of year the birds can appear, gliding, hovering, or plunging talons-first, at virtually any daylight hour. Occasionally, the dramatic action of an Osprey capturing a fish occurs in places where the city’s downtown skyline serves as a backdrop.

A photograph of such action is nothing special in the age of Photoshop, but to witness the event firsthand, especially from the bike trail terrace of reclaimed industrial riverbank, is to reap a visual dividend from all our investments to keep our water clean.

For more information visit the Game Commission’s Osprey webpage.

Patrick McShea, Division of Education at Carnegie Museum of Natural History, mcsheap@carnegiemnh.org (Courtesy: Watershed Weekly)

10/20/2006