Caspian Terns at Eagle Bluffs

Early this morning, while birding at Eagle Bluffs Conservation Area on the Missouri River floodplain, I saw what appeared to be two large gulls, backlit by the rising sun.  On closer inspection (and with the sun at my back), I realized that they were Caspian terns, identified by their large size, stocky frame, black cap, modestly forked tail and thick, red-orange bill.

Found across the globe, Caspian terns nest in colonies, favoring coastal beaches or those along islands in large lakes and rivers; in North America, their breeding grounds include both coasts, southern Alaska, Canada, the Pacific Northwest, California, the Intermountain West and the Great Lakes.  Up to five eggs (usually two or three) are laid in a nest scraped from the sand and coated with dry vegetation.  Their young are slow to mature and often remain with their parents through the first winter, begging for fish that the adults snare from the surface.

By late summer, Caspian terns that breed in the north begin to move south, following the coasts or traveling along major rivers of the interior.  Heading for southern beaches of the U.S., the Caribbean and Mexico, some pass through the Heartland and, this morning, I was fortunate to encounter two of those migrants at Eagle Bluffs.