Gull-Billed Tern

Gelochelidon nilotica
Range Map

Even though the Gull-Billed Tern prefers to remain close to the oceanic coasts of North and South America, it is primarily a terrestrial feeder, often eating insects, crabs, and lizards. A recent breeder in San Diego, its residence and breeding activity is closely studied. Its presence here is a mixed blessing; as a terrestrial, not aquatic hunter, it sometimes preys on the chicks of the endangered California Least Tern and Western Snowy Plover. Biologists studying this species and its endangered prey, wish it would stick to one of its favorite prey species; the Pacific Mole Crab.

There are six recognised subspecies of these birds:

  • G. n. nilotica breeds in Europe and northern Africa, and east through the Middle East, and the Indian subcontinent, and China. They spend winters from tropical Africa through the Persian Gulf and India.
  • G. n. affinis breeds in eastern Asia and spends winters in southeast Asia.
  • G. n. macrotarsa makes its home in Australia. In winter, some roam to New Guinea.
  • G. n. aranea breeds in the eastern USA and south to the Caribbean, and spends winters along the Central American coasts and south to Brazil and Peru.
  • G. n. gronvoldi lives from northern South America to Argentina.
  • G. n. vanrossemi breeds in the western USA in California, Mexico, and spends winters south to Ecuador.

Most of my meetings with Gull-Billed Terns have occurred while in the company of biologists studying these and other tern species. However, I’ve also met them at the Salton Sea in Imperial County (California).

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