Wintering Birds at Conowingo Dam

      On February 2, 2016, I spent two hours at Conowingo Dam on the Susquehanna River in northern Maryland to experience wintering birds.  I saw many birds of several kinds, and some of their activites during the short time I was there.
     The dam holds water above it, letting some go through its turbines to generate electricity.  But the water level below the dam is low, revealing fish; and unfrozen in winter because of the turbulence of the water that fell through the generators and welled up below the dam.  That open water in winter, particularly when everthing else is frozen shut, is a dinner bell for fish-eating birds and other avian species.    
     Many ring-billed gulls and several each of herring and great black-backed gulls were the first birds I saw.  Some gulls were flying back and forth low over the river to get food while others rested on gravel bars and mid-river boulders between feeding forays.  Twice, many of the gulls flew up in a big, swirling mass when a hunting bald eagle sailed over them.  The petite ring-bills were graceful on the wing; their flight was light and airy.  But the large herrings and great black-backs were ponderous and powerful in flight.  All these gulls catch live fish and scavenge them.  But black-backs are also pirates, stealing fish from smaller gulls and common merganser ducks.  
     The longer I stayed at the dam, the more bald eagles, both adults and immatures, I was thrilled to see.  There must have have been over 20 of them that I saw soaring in the air, or perched on shoreline trees, mid-river boulders and on tall power towers.  One adult bald flew down-river, carrying a fish in its talons.  And five eagles fought over a dead fish on a gravel bar near shore.  Bald eagles are scavengers and pirates, as well as catchers of live fish and other critters.
     On February 3rd I saw on the internet that someone counted over a hundred bald eagles at Safe Harbor Dam on the Susquehanna in Pennsylvania.  Fifty years ago, and less, a person would have been lucky to see one bald at Safe Harbor.  Someone else on the internet noted that perhaps many of those eagles at Safe Harbor came from Conowingo, which is several miles south of Safe Harbor.  And another person counted over 80 bald eagles on February 1 in Lancaster County, Pennsylvania farmland, which adjoins Maryland.  There is a great number of wintering bald eagles at Conowingo, Safe Harbor, Lancaster County farmland and other, nearby places these days, which is a tribute to the eagles' adapting and people who have been instrumental in bringing bald eagles back from the brink of extinction.
     Over 20 black vultures were around the Conowingo Dam.  Some were in the air, while others perched on shoreline trees and power towers.  Black vultures are unmistakable in flight, intermittently soaring and rapidly beating their wings.
     Black vultures and turkey vultures, of which I saw a few at Conowingo, are scavengers.  Both species will eat any dead animal, including fish along waterways and impoundments.  Turkey vultures are better at finding carcasses because they have a well-developed sense of smell, something that almost all other birds do not.
     American crows and fish crows winter along the Susquehanna, including at Conowingo Dam.  They, too, scavenge fish and other animals that wash up on shore.
     I saw three other species of fish-eaters at Conowingo on February 2, including several great blue herons, a belted kingfisher and several common merganser ducks.  These species catch different sized fish and hunt them in different ways, all of which reduces competition among them.  Herons wade in more shallow water and grab larger fish with their long beaks.   Kingfishers dive anywhere in the water bill-first to catch small fish in their bills and mergansers slip under water from the surface to seize small fish in their serrated beaks.
     A few each of Canada geese, mallard ducks and black ducks rafted on the river the day I was there.  The rest on the river and other bodies of water, but twice-daily fly to harvested corn fields to feed on corn kernels.
     A flock of rock pigeons live and nest on the dam, as their ancestors have on rock cliffs above the Mediterranean Sea.  These pigeons drop to the river to drink, but fly swiftly to fields to feed on seeds and grain.
     All the birds I saw wintering at Conowingo Dam have a reason to be there.  The community of birds they create at the dam is well worth experiencing any winter.