GULL-BILLED TERN. 95 



Sterna macrotarsa Gould, Synops. Birds Austr., pt. n., pi. (37), April let, 1837 : Tasmania. 

 Gelochelidon nilotica normani Mathews, Austral Av. Rec., Vol. II., pt. 7, p. 125, Jan. 28th, 

 1915 : Normanton, Queensland. 



DISTRIBUTION. Australia generally and Tasmania. 



Adult male in breeding -plumage. General colour above very pale grey on the 

 back, wings, and scapulars ; primary-quills silvery -grey, white on the inner webs, 

 the outer quills edged with dark brown on the outer webs ; upper tail-coverts and 

 tail pure white ; crown of head black ; feathers of the nape white with black tips ; 

 chin, throat, and entire under-surface white, like the axillaries and under wing- 

 coverts ; bill black, mouth orange, iris dark hazel ; feet and legs black, soles with 

 an orange tinge. Total length 432 mm. ; culmen 45, wing 342, tail 141, tarsus 36. 



Adult female. Similar to adult male but smaller in all measurements. 



Adult male in winter. Differs from the male in breeding-plumage in the absence 

 of the black on the head and nape, which is represented by white feathers more or 

 less streaked with black ; ear-coverts and feathers surrounding the eye black. 



The female in winter has the same plumage as the male in the same season. 



Immature. Pale grey, the feathers edged with pinkish -buff above ; the head 

 and nape with short black shaft-lines, a small black spot in front of eyes ; ear-coverts 

 ashy -black ; feathers of upper back with darker centres and broad pinkish -buff 

 edges ; rump with pale tips ; tail-feathers with darker tips edged with white ; 

 scapulars and inner secondaries grey, bases with dark triangular patches and broad 

 pinkish -buff edges ; coverts with pale tipping ; under-surface pure white. 



Immature with down adhering. Similar to preceding but paler ; head fainter, 

 streaks less pronounced and pinkish-buff obscure ; scapulars and upper back 

 pinkish-buff with dark shaft-lines to latter feathers only ; scant buff tipping to 

 coverts ; down on rump and tail-feathers which are pale grey with obsolete tipping ; 

 under-surface pure white with down still present ; ear-coverts scarcely noticeably 

 darker, but dark crescent in front of eye ; bill brownish, tip of lower mandible brown, 

 base paler ; feet brown. 



Nestling in down. Above pale brownish-grey with a few scattered brownish 

 blotches ; a few small spots on back of head, forming two irregular stripes on sides 

 of neck, and a medium stripe down middle of back, and two spots on sides of rump p 

 winglet with a dark spot at base ; under-surface pure white ; bill brown ; legs and 

 feet orange-brown. 



Nest. Placed close to one another, and composed of a few bits of dry grass 

 or stems of cane grass, on a small piece of ground surrounded by water. 



Eggs. Clutch, two to four ; buffy -white or whity-brown, sparingly marked 

 with light umber, the remainder of the surface being boldly splashed and spotted 

 with purplish-red and purplish -grey, some with obsolete patches of a lighter tint 

 appearing as if beneath the surface of the shell ; axis 51-55 mm., diameter 37-38. 



Breeding-season. April, May, November. 



Distribution and forms. From Europe through Asia to Australia, wintering 

 in Africa. Also breeding in North and South America. Six subspecies have been 

 separated : G. n. nilotica (Gmelin) from Europe and North Africa (winter) ; av. 

 measurements : culmen 39-41, wing 310-320 mm. ; G. n. aranea (Wilson) from- 

 North America, with shorter bills and wings ; av. culmen 34-37, wing below 30^ 

 mm. ; G. n. affinis (Horsfield) from Java (winter) and India ; with paler coloration 

 above ; shorter bills and same wing length at typical form ; G. n. macrotarsa (Gould) 

 from Australia in its more powerful and longer bill, longer legs, long wing and paler 

 coloration (G. n. normani Mathews has been named on account of its smaller bill) ; 

 G. n. addenda Mathews, from China, in its short and stout bill with paler coloration 

 approaching preceding ; av. culmen 36-37 mm. ; wing 310 mm. ; and G. n. gronvoldi 

 Mathews, from South America with long bills and long wings, nearly as big as G. n.- 

 macrotarsa, av. culmen 42^45 mm., wing 325. 



