Sterna leucoptera Meisner and Schinz, Vog. Schweiz (1815), 264.
Hydrochelidon leucoptera Saunders, Cat. Birds Brit. Mus. (1896),
25, 6; Sharpe, Hand-List (1899), 1, 133; Oates, Cat. Birds' Eggs
(1901), 1, 174; McGregor and Worcester, Hand-List (1906), 20.
Mindanao (Steere Exp., Bourns & Worcester). Central and southern
Europe to central Asia and China; Australia, New Zealand, Africa
in winter.
"Adult in breeding plumage.--Head, neck, and upper back dark, glossy
black; coverts on the carpal joint pure white; greater wing-coverts
pearl-gray; secondaries darker, passing into slate-gray; primaries
frosted with pearl-gray, which soon wears off the outer quills,
leaving the webs sooty black, with a well-defined narrow whitish
streak down the middle of the inner webs of the four outer primaries;
shafts white; back and rump grayish black; upper tail-coverts and
tail pure white; under parts deep black; vent white; flanks, under
wing-coverts, and axillars black. Bill livid red; feet orange-red;
webs of toes much indented. Length, 236; culmen, 28; wing, 208; tail,
79; tarsus, 19; middle toe with claw, 25.
"Adult in autumn and winter plumage.--In the latter part of July,
when the molt begins (in Europe), the bird is curiously parti-colored,
the new feathers of the head, neck, and under parts being white and
those of the back gray (paler than in Hydrochelidon nigra). Later,
the under parts, including the under wing-coverts and axillars,
become white, the crown and nape being merely mottled with black;
but by the following April the black color has reappeared to a
considerable extent, especially in the axillars.
"Immature.--In birds which are not mature, though capable of breeding,
the black of the under parts has a brownish tinge and the tail-feathers
are pearl-gray, especially toward the tips. In winter like the adult.
"Young.--Similar to the winter plumage of the somewhat immature
bird, but much mottled with dark brown on the upper parts, and the
tail-feathers slightly darker gray with a brownish tinge toward the
tips; upper tail-coverts always white.
"Nestling.--Ruddy fawn-color, mottled with black above, unspotted
pale cinnamon-brown below." (Saunders.)
"Observed and shot by us in Mindanao, where it was flying over the
rice-fields." (Bourns and Worcester MS.)