the elegant tern (thalasseus elegans , syn .
sterna elegans - see bridge et al .
, 2005) is a seabird of the tern family sternidae .
it breeds on the pacific coasts of the southern usa and mexico and winters south to peru , ecuador and chile .
this species breeds in very dense colonies on coasts and islands , including montague island (mexico), and exceptionally inland on suitable large freshwater lakes close to the coast .
it nests in a ground scrape and lays one to two eggs .
unlike some of the smaller white terns , it is not very aggressive toward potential predators , relying on the sheer density of the nests (often only 2030 cm apart) and nesting close to other more aggressive species such as heermann's gulls to avoid predation .
the elegant tern feeds by plunge-diving for fish , almost invariably from the sea , like most thalasseus terns .
it usually dives directly , and not from the "stepped-hover" favoured by the arctic tern .
the offering of fish by the male to the female is part of the courtship display .
surprisingly , this pacific species has wandered to western europe as a rare vagrant on a number of occasions , and has interbred with the sandwich tern in france; there is also one record from cape town , south africa in january 2006, the first record for africa .
this is a medium-large tern , with a long , slender orange bill , pale grey upperparts and white underparts .
its legs are black .
in winter , the forehead becomes white .
juvenile elegant terns have a scalier pale grey back .
the call is a characteristic loud grating noise like a sandwich tern .
this bird could be confused with the royal tern or forster's tern , but the royal tern is larger and thicker-billed and shows more white on the forehead in winter .
out of range , it can also be easily confused with the lesser crested tern .
see also orange-billed tern , and the external link below .
some useful points to separate it from other terns in this group:it is marginally paler above than the lesser crested tern with a white (not grey) rump .
it a slightly longer , more slender bill and the curve of the bill is different from lesser crested tern .
the black of the crest that comes down from the crown extends through the eye , creating a small black "smudge" in front of the eye .
on royal tern , the black crest stops at the eye .
the crest is more shaggy than in lesser crested tern .
