Black tern

Background

The black tern was formally described by Carl Linnaeus in 1758 under the name Sterna nigra, with the type location later restricted to Uppsala, Sweden. It is now placed in the genus Chlidonias, introduced by Constantine Rafinesque in 1822. The genus name derives from Ancient Greek for 'swallow-like', and the species name from Latin for 'shining black'. Old English names include 'carr swallow' and 'blue darr'.

Hunting Strategy and Dietary Flexibility

The Caspian tern is a committed piscivore, though its menu extends beyond fish. Its primary hunting technique involves hovering high above the water's surface before executing a steep, full-body plunge to strike prey beneath. This aerial ambush allows the bird to target fish in both open ocean and freshwater lakes. On occasion, the tern supplements its diet with large insects, the nestlings and eggs of other bird species, and small rodents.

Notably, these birds are willing travelers in pursuit of food; they may range as far as 60 kilometers from their breeding colony to locate suitable foraging grounds, whether that means a coastal bay or an inland lake. This flexibility in both habitat use and prey selection grants the species a degree of ecological resilience. The combination of a powerful diving technique, a long thick bill well-suited for gripping slippery fish, and a willingness to cover considerable distance makes the Caspian tern a highly effective hunter across a wide variety of aquatic environments, from saltwater to freshwater systems.

Did You Know?

• The black tern's call has been described as a high-pitched 'kik', and a large flock's sound as 'deafening'.
• The North American race, C. n. surinamensis, is distinguishable from the European form in all plumages.
• Unlike white Sterna terns, black terns do not dive for fish but forage on the wing, picking items at the water's surface.