BIRDS OF THE BRITISH ISLES. 



!83 



Blacft ^ern. 



The Black Tern {Hydrochelidon nigra^ Linnaeus) is a fairly 

 regular spring and autumn coasting migrant to the British 

 Isles, and inhabits the South-western Palearctic Region. 

 The adult in summer has the head and neck deep slate- 

 grey ; crown and nape, blackish; under wing-coverts, light 

 grey; upper parts and tail, dark bluish-grey, the latter 

 forked ; throat, breast, and abdomen, deep slate-grey ; vent 

 and under tail-coverts, white; irides, dark hazel; bill, black; 

 legs and feet, deep reddish-brown. Length, about ten 

 inches. The adult in winter has the crown, nape, fore- 

 head, cheeks, throat, and front neck, white ; remainder of 

 plumage, as in summer. 



