HYDROCHELIDON. 87 



^' 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, whicli 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, 

 tlie new feathers of the head, neck, and under parts being white and those 

 of the back gray (paler than in Hydroclielidon 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 breed- 

 ing, 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. — Euddy 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.) 



77. HYDROCHELIDON HYBRIDA (Pallas). 



WHISKERED TERN. 



Sterna hybrida Pallas, Zoogr. Rosso-Asiat. (1811), 2, 338. 



Hydrochelidoii hybrida Saunders, Cat. Birds Brit. Mus. (1896), 25, 10; 

 Blanford, Fauna Brit. Ind. Bds. (1898), 4, 307, fig. 70 (head); 

 Sharpe, Hand-List (1899), 1, 33; Gates, Cat. Birds' Eggs (1901), 1, 

 175; McGregor and Worcester, Hand-List (1906), 20. 



Luzon {Meyer, Murray, Whitehead, McGregor) ; Mindanao (Bourns if Worces- 

 ter, Mcarns) ; Palawan {Whitehead, Steere Exp.) ; Negros {Whitehead). South- 

 western, central, and southern Europe to China, Malay Archipelago, Australia, 

 Africa. 



"Adult male in breeding plumage. — Forehead, crown, and nape deep 

 black ; from the gape to the nape a conspicuous white streak ; upper parts 

 slate-gray, darker on the primaries, except when these are new and 

 frosted; shafts white; inner webs of outer pairs of primaries white on the 



