Beak of the Week – Black Tern

The Black Tern is probably the most aesthetically unique of the terns found in North America. While in breeding plumage the Black Tern has a fully black head, breast, and belly with gray wings and a small slender bill. In the non-breeding season this tern undergoes a significant plumage change where all its black parts turn white except for a small patch of black that remains behind the eye.

Black Terns are on the smaller end of North American Terns, with only the tiny Least tern being smaller in size. Most other tern are piscivores (fish eaters) and while Black Terns are known to catch fish, the bulk of their diet consists of small invertebrates caught while in flight. Black Terns are very social, usually migrating and roosting in flocks of around 100 birds but sometimes up to ten thousand.

Black Terns prefer marshy habitats for nesting and foraging. They breed in loose colonies, often having a fair amount of space between nests. Nests are placed very low in the marshes, often atop a floating mat of vegetation. It is not uncommon for the eggs of a Black Tern to be damp during incubation. Young typically take about 25 days to reach fledging age and parents may continue to feed the young up to two weeks after their first flight.

Black Terns breed in the northern parts of the central U.S. and throughout most of central Canada. During migration they are commonly seen along three of the four major flyways of North America but are rarely seen in the U.S. Southwest. They spend their winters out at sea or in South America. You can find Black Terns at our Bolivar Flats Sanctuary loafing with large groups of other tern species!