Caspian Tern

Hydroprogne caspia
Range Map

We consider the Caspian Tern the world’s largest tern. Their raspy croaking voice could pass for a sound effect for a pterodactyl in a 1950s Sci-Fi film. These birds have territories on five continents. They take their common name from the Caspian Sea, a region where most of the Eurasian population spend their summers.

Despite their world-wide range, most researchers believe the Caspian Tern is monotypic (i.e. no subspecies).

In North America, most of these birds breed from the Great Lakes in the east, to the sub-arctic prairies of Canada, but on the west coast there are breeding colonies along the lower Columbia River, around the San Francisco Bay and at several Southern California locations, including South San Diego Bay.

I’ve had the privilege of accompanying biologists on their surveys at South San Diego Bay. The tern colonies there include Elegant, Royal, Least, Gull-Billed, Caspian, Forster’s Terns and Black Skimmers. A walk through a tern nesting colony can be hazardous if Caspian Terns are present. These birds will attack from behind and wing-whip intruders, sometimes resulting in blood spills.

While I visited south Texas, I met Caspian Terns in three locations around the Lower Rio Grande Valley. The first was in 2020, at Laguna Atascosa NWR during the first days of the pandemic. Boca Chica Beach, at the mouth of the Rio Grande, was also a productive location for these and other birds. Probably the best place I met Caspian Terns was on South Padre Island in the wetlands south of the Convention Centre.

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