(2074) Thalasseus sandvicensis sandvicensis.
THE SANDWICH TERN.
Sterna sandvicensis Lath., Gen. Syn., Suppl., i. p. 290 (1787) (Sand- wich). Sterna cantiaca. Blanf. & Oates, iv, p. 312.
Vernacular names. None recorded.
Description In Summer. Upper parts of the head from forehead to nape and crest and running under the eye, where it is broken by a white patch, to above the ear-coverts black; upper plumage pearl-grey, whitish on the hind-neck and pure white on the rump and tail; primaries darker silvery-grey on the outer webs, blackish on the inner webs with broad white edges extending to the tip; lower plumage from the lores pure white.
Colours of soft parts. Iris brown; bill black, the tips of both mandibles pale horny-yellow; legs and feet black.
Measurements. Wing 295 to 312 mm.; tail 140 to 161 mm.; tarsus about 27 to 29 mm.; culmen 52 to 56 mm.
In Winter the black crown is replaced by white, some black showing round the eye, streaking the crown and heavily streaking the hind-neck and longer feathers of the creast.
Young birds have the crown and nape black with tiny buff bars turning to white on the nape; hind-neck almost immaculate white; remaining upper parts sometimes tinged with buffy and with broad black bars; below white.
Distribution. Europe and Western Central Asia. In Winter South to Northern Africa and down the coasts to Cape Colony; the Persian Gulf as far South as the Mekran coast and Sind.
Nidification. The Sandwich Tern breeds from the end of May to the end of June, generally in rather small colonies of some dozen to twenty pairs but occasionally in great colonies of many hundreds. Often they associate with other Gulls and Terns and suffer from the depredations of the former. Even when the colonies are very large they split up into smaller groups, a dozen or so pairs laying their eggs in a small sand-hill only a few feet across, similar groups laying ten to twenty yards away from these. They are very careless birds and no other Terns so often destroy their own eggs by sweeping them out of the nesting hollows, whilst few other Terns are so addicted to changing their breeding-quarters for no reason. No nest, is made beyond the scratching out of a hollow in the sand but they always select sand-hills or small patches of sand, even though the greater part of their breeding-ground is shingle. The eggs number one or two only and clutches of three - outside collections - are very rare. They are extremely beautiful, the ground varying from pure white to deep salmon, dark brown, bright buff or yellow stone, whilst the markings are generally very bold and handsome, sometimes huge blotches, sometimes clouds and smudges, sometimes small spots or very rarely, scrolls. These may be black, deep purple or reddish-brown or deep red, the secondary marks being of pale lavender. One hundred eggs average 51.7 X 36.1 mm.: maxima 55.6 x 36.2 and 53.2 x 39.0 mm.; minima 44.0 x 34.7 and 51.0 x 33.4 mm. (Jourdain).
Habits. This is a Sea-Tern and frequents the coast line wherever found, seldom venturing far inland. It has a loud, harsh call, easily distinguishable from the smaller Terns but its flight is quite typical of the family. Its food is almost entirely fish and small mollusca, the young being fed principally on sand-eels.