430 



STEENID^ 



HYDEOCHELIDON 



757. Hydrochelidon hybrida. Whiskered Tern. 



Sterna hybrida, Pallas, Zoogr. Bosso-Asiat. ii, p. 338 (1811). 

 Pelodes hybrida, Ourney, in Andersson's B. Damaral. p. 362 (1872). 

 Hydrochelidon hybrida. Dresser, B. Eur. viii, p. 315, pis. 588-9 (1877) ; 



Sharpe, ed. Layards B. S. Afr. p. 699 (1884); Symonds, Ibis, 1887,' 



p. 335 ; Saunders, Cat. B. M. xxv, p. 10 (1896) ; Shelley, B. Afr. i. 



p. 162 (1896) ; Beichenow, Vog. Afr. i, p. 72 (1900) ; Haagner, Ibis, 



1902, p. 574. 

 Hydrochelidon leucopareia, Hohib ^ Peh. Orn. Siirl-Afr. p. 332 (1882). 



Description. Adult Male in breeding plumage. — Forehead, 

 crown and nape black ; sides of the face from the gape below the 

 eye to the nape white ; rest of the upper plumage slaty-grej', 

 darkest on the primary quills ; outer primaries with the inner webs 

 white to a considerable extent ; outer web of the outer tail-feathers 

 also white ; beneath the chin is white gradually darkening to black 

 on the abdomen and flanks; vent, under tail-coverts and under 

 wing-coverts white. 



Fig. 137.— Left foot of Hydrochelidon hybrida, from above. 



Iris brown ; bill blood-red ; feet Vermillion ; webs much indented 

 but not quite so strongly as in H. leucnptera. 



Length about 10-0; wing 9-5 ; tail 325 ; culmen 1-2 ; tarsus -95. 



The sexes are alike ; in non-breeding plumage the forehead is 

 white, the crown and nape mottled and streaked with black, the 



