BLACK-HEADED GULL 411 



Both sexes take part in the task of incubation. 



Geographical distribution. The breeding-grounds extend 

 over a wide area of Sub-arctic and Temperate Europe east 

 of the Baltic ; eastward this bird breeds in Temperate Asia. 

 In winter it migrates to the Mediterranean Basin and to 

 North Africa as far as Egypt. 



DESCRIPTIVE CHARACTERS. 



PLUMAGE. Adult male nuptial. Head and upper neck, 

 black ; rest of neck, white ; back and wings, * french ' grey ; 

 primaries, grey, broadly edged with white, darker on their 

 inner webs ; axillaries and under wing-coverts, blackish, con- 

 spicuous when the bird is flying ; tail, white ; throat, breast, 

 and abdomen, white, exhibiting a delicate pinkish hue. 



Adult female nuptial. Similar in plumage to the male. 



Adult winter, male and female. Forehead, white ; top 

 of head, back of neck, and cheeks, greyish. 



Immature, male and female. Top of head and back of 

 neck, streaked with brownish-grey ; back and wings, mottled 

 with dark brown, and edged with buff; tail, banded sub- 

 terminally with a similar colour ; primaries, black, edged 

 internally with white ; under wing-coverts and axillaries, 

 white. 



BEAK. Lake-red. 



FEET. Vermilion-red. 



IEIDES. Brownish-black. 



AVERAGE MEASUREMENTS. 



TOTAL LENGTH 11 in. 



WING 8'75 



BEAK 1-25 



TAESO-METATARSUS 1 



EGG 1-65 x 1-1 in. 



BLACK-HEADED GULL. Larus ridibundus (Linnaeus). 



Coloured Figures. Gould, ' Birds of Great Britain,' vol. v, pi. 

 64; Dresser, 'Birds of Europe,' vol. viii, pis. 596, 597, 

 fig. 1 ; Lilford, ' Coloured Figures,' vol. vi, pi. 19 ; Booth, 

 ' Rough Notes,' vol. iii, pis. 35, 36. 



This familiar species is widely distributed, not only 

 along the sea-coast of the British Isles, but also, during 

 the breeding-season, in marshy situations, often miles away 



