Black Brent 163 



Adult Birds of Both Sexes 



Colouring as in ordinary brent {Brant a bemicla), but on the whole considerably 

 darker and blacker. Bill said to be somewhat more massive and broader at the base, 

 although I cannot confirm this, as I have not found these differences in dry skins, but my 

 material was small. 



On neck a white collar, much broader than in common brent, and always closed in 

 front, and almost always so behind ; I have, however, met with examples, perhaps not very 

 old, but apparently adult, in which the junction of the white collar behind was incomplete, 

 but became so only on raising the elongated black plumes of the neck. 



Head, neck, upper part of body and breast, very dark brown-black ; under-part of 

 body, that is, belly and flanks, dead black, almost indistinguishable from black of breast, 

 but still more sharply contrasted with the pure white of the hind part of belly and vent. 

 Both upper and under tail-coverts, which completely reach the tips of the brown-black tail 

 feathers, pure white. Soft-parts black, as in common brent, and under-part of wings as in 

 latter, but slightly darker. 



Length ........ 560-730 mm. (=22-29 in.). 



Wing ...... .„ . . . 330-350 mm. (= 13-1375 in.). 



Culmen ........ 30-36 mm. (= 1. 20-1. 35 in.). 



Tarsus ......... 56—66 mm. (=2.20-2.50 in.). 



Weight from 3^ to 5 English lbs., and probably sometimes rather more. 



Young Birds 



Colouring as in adults, but white collar obscurely marked and totally wanting in birds 

 in first plumage. Greater wing-coverts and secondaries with white tips ; feathers on flanks 

 entirely greyish brown without white tips (Ridgway). 



As is apparent from this description, neither dimensions nor any other essential 

 characters, with the exception, perhaps, of a rather more massive bill, 1 distinguish this bird 

 from the common brent. 



On the other hand, it is sharply and constantly differentiated from the latter by the 

 very broad collar always well closed in front (and often behind) and by the black belly and 

 flanks matching the breast. And since these two characters are, it seems, constant, this 

 form is very distinct and easily separated from Brant a bemicla, but nevertheless only as a 

 variety. Some examples of the typical form, and also of the light-bellied variety (B. bemicla 

 glaucogaster) also sometimes have the white patches on the sides of the neck meeting in 

 front, but this is only as a rare exception, clearly, as it seems to me, pointing to the specific 

 relationship of all three forms of brent. The completely isolated geographical distribution of 

 B. nigricans alone sharply separates it from the two others. 



Geographical Distribution 



The range of the nemok is by no means difficult to work out. The Arctic zone 

 from the Lena to the extreme east of the Asiatic shore and (passing over the islands in 



1 Although Taczanowski speaks of the more massive bill of this form, this is not borne out by the dimensions he gives, so that it is 

 desirable to obtain accurate measurements of bills from freshly killed birds. 



