THE BLACK TERN. 687 



grey ; tail-feathers as upper-parts, very narrowly fringed hoary, 

 outer web of outermost feathers hoary ; primaries : outer webs 

 and tips pearl-grey (becoming dark slate when worn), inner webs 

 darker but inner edge very narrowly fringed whitish and basal inner 

 part ash-grey extending towards tip in wedge-shape, shafts dark 

 brown at tips otherwise brownish-white but darker when freshly 

 grown ; secondaries pearl-grey (becoming dark slate when worn), 

 inner portion of inner webs pale grey ; innermost secondaries,, 

 greater and median coverts pale slate-grey ; lesser coverts dark 

 slate with hoary fringes. This plumage is acquired by complete 

 moult commencing sometimes as early as May and June and 

 completed in late autumn or winter. N.B. — Moult in Europe before 

 migration usually confined to body and a few tail-feathers but 

 occasionally inner primaries ; moult is completed in winter- 

 quarters but very few winter birds are available. Summer. Male — 

 Material insufficient to give details of moult which includes wings 

 and tail, and is complete by April or May. Those birds with con- 

 siderable moult in May and June are probably first summer. Fore- 

 head, whole crown to base of neck, bordering on mantle, sides of 

 head and sometimes chin black ; rest of upper -parts slate-grey 

 slightly darker than winter ; under-parts blackish-slate except under 

 tail-coverts, which are white ; axillaries slate -grey ; under wing- 

 coverts ash-grey ; tail and wings as winter but lesser coverts paler with 

 hoary tinge. Female. — Like male on upper-parts but black of crown 

 not extending on to mantle and sides of head dark slate -grey ; 

 under-parts dark slate -grey not blackish as in male, chin and throat 

 usually paler grey. 



Nestling. (Plate 10). — Completely covered with longish, soft 

 down with fine hair -like tips. Line across fore-head, through lores 

 and broad circle round eyes white ; upper-parts rich buff with 

 blotches and rather broken lines of black, small irregular blotches 

 not quite connected on each side of crown, longer streak on back of 

 neck, long streaks on each side of upper-mantle, somewhat broken 

 and irregular on sides of back, streak down centre of rump ending 

 in blotch, irregular blotches on wings ; tip of wing greyish-white ; 

 apex of chin greyish -white, rest of chin and throat dark buff to sooty- 

 brown ; middle of breast greyish white ; sides and belly dark 

 buffish-grey. Down is 

 replaced by juvenile 

 feathers, to tips of 

 which it clings. 



Juvenile. — Fore- 

 head extending over 

 eye white often washed 

 brown ; crown, middle 1 



Of nape and upper ear- j uve nile of the Black Tern (Chlidonias n. niger.) 



coverts sooty - black, 



feathers narrowly edged pale brown to whitish ; lower -neck and 



sides of nape white, feathers often tipped pale brown ; upper- 



