THE COMMON TERN. 



709 



black washed grey and inner webs dark grey towards tip ; primaries : 

 outer webs and tips silver-grey,* shafts white, inner webs white 

 with in 2nd (outer) primary a grey-black line along shaft increasing 

 in width towards tip and on level with tip of 5th primary extending 

 to half or more than half width of inner web and on level with tip 

 of 6th exceeding width of outer web, in 3rd to 6th primaries black 

 line is wider and blackish tips longer enveloping white in form of a 

 wedge, inner feathers greyer, not so blackish and edged white to tips 

 of inner webs ; secondaries grey (silvery on outer webs) tipped 

 white and with inner portion of inner webs white ; primary-coverts 

 silver-grey ; median and greater coverts blue-grey, latter narrowly 



Distal portions of outer (2nd) primaries of A. the Arctic Tern, B. the Common Trim. 



edged white ; lesser coverts dark, almost blackish, grey with incon- 

 spicuous ashy fringes. This plumage is acquired by complete moult 

 commencing July- Aug. with body, tail, and inner primaries and 

 completed in winter-quarters. Summer. — A moult of body, tail- 

 feathers, and wing-coverts takes place Feb. -Mar. but it seems 

 doubtful if all primaries and secondaries are moulted twice, 

 insufficient winter material being available to determine this. 

 Whole fore -head and crown (to level of lower part of orbit) and 

 nape jet-black ; back of neck blue-grey as mantle, but white basal 

 portion of feathers not always entirely concealed ; mantle, scapulars 

 and back blue-grey, rather darker and bluer than winter, tips of 

 lower scapulars white ; rump and upper tail-coverts white ; lower 

 part of lores, sides of head, and neck and chin as well as under wing- 

 coverts and under tail-coverts white ; axillaries washed grey ; rest 

 of under -parts grey with a mauve tinge (varying in strength but not 

 white as winter) ; tail-feathers paler than winter, inner webs of all 

 white, outer webs paler grey than winter, central pair white, some- 

 times washed grey on outer webs ; primaries and secondaries as 

 winter ; all wing-coverts blue-grey as mantle, lesser coverts along 

 edge of wing white. 



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



* The rami are black and only the radii silver-grey, the latter become 

 gradually worn off and thus the outer webs and tips become black, especially 

 in the outer feathers which are most exposed. — H.F.W. 



