WINTER BIRDS AT CONOWINGO DAM

      A variety of larger birds have been wintering at Conowingo Dam on the Susquehanna River in northern Maryland for several years.  They are numerous, fish-eating birds, currently including bald eagles, ring-billed gulls, double-crested cormorants, great blue herons and black vultures, all of which procure their food in various ways.  And all of which are seen by video cameras and on computer screens.        Conowingo Dam backs up the Susquehanna into a long lake with little current.  River water tumbles through several turbines, which spin in the falling water, creating electricity.  The water then gushes into the river below the dam, creating turbulence that doesn't freeze.  Dead, injured or disoriented fish of smaller sizes also tumble through the turbines and into the river below the dam, where they are vulnerable to fish-eating birds already mentioned.  

     Up to 250 magnificent bald eagles of all ages winter at Conowingo Dam.  They roost on trees, boulders and power towers along the river at night and catch larger hickory shad, American shad, catfish, black crappies, walleyes and striped bass from the turbulence below the dam.  

     Each majestic eagle spies a fish near the surface while it soars easily on broad, flat wings.  The large bird sweeps down gracefully to the water, extends its eight sharp, curved talons on two feet and attempts to snare the fish, often with success, without entering the water.  When successful, each eagle then flaps ponderously, with its prey in its talons, to a nearby perch to consume its catch.  Sometimes, that successful eagle is chased and attacked by one, two or three eagles intent upon stealing its victim.  Sometimes two eagles lock talons in the tussle and spin down to the river, letting go of each other at the last second.

     Clouds of sleek, gray and white ring-billed gulls fly buoyantly back and forth over the turbulent water just below the dam as they watch for vulnerable, smaller fish to grab in their beaks and ingest.  Ring-bills also scavenge dead fish washed up on shore and left-overs from eagle meals.  These gulls rest on mid-river boulders between feeding forays, but are wary of bald eagles, who kill and eat some of them.  An eagle passing overhead puts up swarms of ring-bills that fly back and forth and finally settle again..

     Stately double-crested cormorants are abundant below Conowingo Dam in recent years.  They float on the rushing water like ducks and dive under water from its surface to catch fish.  Cormorants rise to the surface to breathe and swallow their catch, where some of them are attacked by gulls who want to steal their fish.

     Scores and scores of cormorants perch between fishing forays on mid-river boulders with the gulls.  But the cormorants dive into the water from those boulders at the close approach of a hunting eagle.   

     Elegant, long-legged great blue herons wade the shallows of the river to catch fish.  When prey is spotted, they thrust out their long necks and bills to seize those fish.  

     Big as they are, these herons, when still, are difficult to spot resting on mid-river boulders because they are gray feathering before gray rocks.         

     Black vultures are another kind of bird that has recently become abundant at Conowingo.  Scores of them are there to scavenge washed up dead fish and other creatures, and leftovers from eagle meals.   These vultures line up on trees and dam walls at night and between feeding forays.        

     Many people come to Conowingo Dam in winter to see these birds, especially the eagles.  And many of those folks take pictures and videos of them, particularly the eagles.  Some of the videos can be brought up on computer screens.

     All these wintering, fish-eating birds at Conowingo are exciting to experience.  They are there because water below the dam remains ice-free all winter, even when impoundments and other parts of the river freeze over.  And there is abundant, vulnerable fish below the dam.  

     In spring, most of these birds will disperse to their nesting territories.  But many of them will return the next winter.  

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