Glaucous Gulls and Great Black Backs

     At least once every winter, I enjoy seeing the many handsome, adult great black-backed gulls along the Susquehanna River in Lancaster County, Pennsylvania.  These magnificent gulls are the largest of their kin in North America, about the size of a Canada goose.  Adult great black-backs seem dazzlingly white, including their under parts, heads and tails, but have black upper wings and backs.  And when mature black backs soar on high, they sometimes remind me at first of adult bald eagles, but then I see the gulls' white bellies. 
     Great black-backed gulls are stately, whether perched on river-side boulders, docks or pilings; or soaring and wheeling across the sky.  And I often see them sitting during winter days on glare shields above street lights on the Route 462 bridge crossing the Susquehanna in Lancaster County.  Always, there is one black-back per shield.
     However, I've only seen a few adult glaucous gulls in my lifetime.  They have white heads, tails and bellies like the black-backs.  But the beautiful, mature glaucous gulls are pale-gray on the tops of their wings and on their backs, which makes them look a bit ghostly, especially in the midst of snow.      Adult glaucous gulls and mature great black-backed gulls have much in common.  At up to 24 inches in length, they are the largest gulls in North America.  They are both hawk-like and predatory, as well as robbers, fishers, and scavengers of almost anything edible.  Both species have big, powerful beaks that help them procure their food, including killing and eating a variety of birds and their eggs and young.  Both species winter in the Mid-Atlantic States, both along the seacoast and inland, the black-backs fairly commonly and the glaucous uncommonly in those states.  Furthermore, a few of each kind winter, at times, around inland, human-made impoundments where they rest overnight, and in landfills where they look for edible scraps.
     Pairs of glaucous gulls nest circumpolar in the northern hemisphere.  Each pair hatches two or three babies per brood on cliff ledges near nesting colonies of birds on islands, on the coasts of the Arctic Ocean, the shores of the Atlantic Ocean south to Newfoundland. and down to James Bay, which is a southern arm of Hudson Bay.  While raising young, pairs of glaucous gulls kill ocean and tundra birds, including dovekies, murres, gulls, ducks and plovers, and the eggs and young of those birds.  They also catch fish and scavenge dead animals.
     The strikingly handsome adult glaucous gulls, and their immatures, in North America winter along the shores of the Arctic Ocean, the coast of the northern Atlantic Ocean south to Long Island, and sometimes farther south, and along the Great Lakes.  This lovely gull utters hoarse croaks for the most part.            
     The majestic great black-backed adults, in North America, nest on the sea coasts of the North Atlantic and Arctic Oceans.  They feed the eggs, young and adults of ducks, terns, smaller gulls, cormorants and other kinds of birds to their two to three young per brood, as well as consume those foods themselves. 
     In North America, this magnificent species winters along the Atlantic Shoreline south to North Carolina, and the shores of rivers and the Great Lakes.  In winter they feed on live fish they catch, fish they scavenge, or rob from other kinds of fish-catching birds, including gulls and diving ducks, and anything else edible.  Black-backs mostly utter deep, guttural croaks that can be heard for a bit of a distance.
     Watch for these two kinds of stately gulls in the Middle Atlantic States in winter.  They are big, handsome species that stir some excitement by the way they get food from and around larger bodies of water.