Bonaparte's Gulls in Southeastern Pennsylvania

     Bonaparte's gulls are special birds along the Susquehanna and Delaware Rivers, and other rivers in North America, during March and April when they migrate northwest by the hundreds, flock after flock, to their nesting territories by lakes in the forests of interior Canada and Alaska.  They are not seen much in southeastern Pennsylvania the rest of the year.  Anyone who wants to see these petite and beautiful gulls must be along rivers early in spring.   
     The majority of Bonaparte's gulls winter along seacoasts, estuaries and the mouths of large rivers. There they flutter over the surfaces of large bodies of water to pick up tiny fish and other edible tidbits near the surface of the water.
     Bonaparte's are pretty, little gulls.  They are dainty, almost tern-like with swept-back wings.  Early in spring when we see them migrating through the Middle Atlantic States and heading northwest, they are crisp-white below, with white tails and heads, and gray above with red legs, dark beaks and a black patch behind each eye.  The most diagnostic feature on them, however, is the long, white stripe on each wing.  Many of those white stripes together on flying Bonaparte's appear to be white flags flapping in the wind.  Those striking, white streaks are evident from a distance and aid in identifying the gulls.  Bonaparte's are the only gulls that have those waving white banners on their wings to be regularly seen on American rivers.   
     Bonaparte's gulls sit in little groups on the water or the gravel bars of mid-river islands to rest between feeding forays.  Even there they are recognizable by the black spot behind each eye and appear dainty.  And in the air, low over the water, they fly back and forth among their fellow gulls, gracefully and buoyantly with powerful wing strokes, with their bills held downward, and watch for small fish and other edibles near the surface.  Many Bonaparte's are so low to the water that they seem to be walking on it.  Interestingly, a distant feeding flock of scores of this species appears like a loose gathering of white butterflies fluttering into the wind.  When potential food is spotted, each gull quickly drops to the surface with a little splash and snares the food with its beak.  
     Bonaparte's nest up to fifteen feet high in spruce and fir trees along lakes and rivers in Canadian and Alaskan forests.  Each female lays two to four eggs in the cradle she made of twigs, grass and, finally, moss.  The parents feed the young in those nurseries.
     Be along the Susquehanna, Delaware and other rivers in March and April to see the beautiful, petite and migrating Bonaparte's gulls.  They are a lovely, entertaining addition to the water birds along those rivers during spring.