Black Tern

I grew up in western Pennsylvania, and last month I briefly visited the “Main Pond” of the Imperial Grasslands, one of my favorite birding spots in Allegheny County. Unfortunately, it’s changed a lot since I was learning about birds there decades ago. I remember the pond surrounded by an immense grassy field, crisscrossed by gravel roads. This time I parked my car on the side of a wide paved road to see that the grassland had been replaced by a forest of large warehouses. Despite the artificial surroundings, the pond was still there, and it still occasionally attracts rare or uncommon birds like the Black Tern I had come to see.

Most terns and gulls are white, often with gray and black wings. Black Terns stand out as one of the few with mostly black feathers, at least during the breeding season (their belly, breast, throat and parts of the head are white in their winter plumage). Also unlike most other seabirds, Black Terns nest in freshwater marshes, where they eat both fish and insects. They have a distinctive way of flying, with deep, stiff wingbeats (almost like a butterfly) and an erratic, zig-zag flight pattern.

Black Terns nest across the northern United States and southern Canada, then migrate to coastal areas in northern South America and western Mexico for the winter. A separate population nests from eastern Europe to western Russia and Kazakhstan, then lives along the Atlantic Coast of Africa during winter. In Pennsylvania, your best chance of seeing Black Terns is from May to early June during spring migration or in the fall between August and early September as they fly south. They can show up anywhere across the state, but they’re never common here, and they don’t stay for long.

Black Terns are listed as an Endangered Species by the state of Pennsylvania. They sometimes nest in the state, but in very small numbers and only in Erie and Crawford counties in the northwestern corner of the state. The Western Hemisphere population of Black Terns has declined by more than half since the start of the Breeding Bird Survey in 1966. The decline is likely due to degradation or destruction of the marsh habitats these birds need for nesting.