brunnich's guillemot. 801 



as in Common Guillemot in autumn. N.B. — Only one in full moult 

 (Aug.) examined. (Ringed " variety " does not occur in this 

 species.) Summer. — Body -moult apparently as in Common 

 Guillemot but no moulting examples available. Upper-parts black 

 with dark greyish tinge especially marked on fore-head, crown, 

 back of neck and upper-mantle ; chin, lores, sides of head to lower 

 edge of eye, sides of neck and throat dark chocolate-brown slightly 

 paler than in Razorbill. 



Nestling. — Like that of Common Guillemot, but white streaks 

 on crown and neck more prominent, and upper-parts with tips of 

 down rather more bufhsh-brown. 



Juvenile,. — Head and throat all round black or with chin and 

 throat dull white, feathers tipped black-brown ; whole upper-parts 

 brown-black, feathers of upper -parts and wing-coverts margined 

 jet-black giving a somewhat squamated appearance ; under-parts 

 white, some feathers of sides and flanks with very narrow blackish 

 margins at tips. As in Common Guillemot and Razorbill tail, 

 primaries and secondaries do not grow with juvenile plumage. 



First winter. — Like adult except for smaller bill and sometimes 

 more black-brown tips to feathers of throat. First summer. — 

 Throat appears to be frequently mottled with white, and upper- 

 parts, and especially wings, become brown about June. 



Measurements and structure. — <$ and § wing 205-226 mm., tail 

 43-51, tarsus 35-39, bill from feathers 32-39, greatest depth 13-17 

 (15 measured). First winter $ and $ wing 195-211, tail 40-45, bill 

 length, 25-31, depth 11-13. Primaries : 1st longest, 2nd 2-5 mm. 

 shorter, 3rd 8-14 shorter, 4th 18-25 shorter, 5th 28-38 shorter. Bill 

 shorter, deeper and wider and more sharply decurved than in 

 Common Guillemot, angle of gonys more prominent, horny ridge 

 along gape wider and much more prominent, noticeable even in 

 nestling. Otherwise structure as Guillemot. 



Soft parts. — Bill black, horny margin of feathered portion blue- 

 slate ; legs and feet anteriorly yellowish-horn with dark joints, 

 posteriorly black ; iris brown-black. 



Characters and allied form. — U. I. arra (Bering Sea) is larger. 

 Distinguished from Razorbill by shape of bill and absence of vertical 

 grooves and from Common Guillemot by prominent horny ridge 

 from nostril to gape and also by its deeper, shorter bill and in winter 

 by absence of black streak through ear-coverts. 



Field -characters. — In summer resembles Common Guillemot 

 closely and associates freely with it, but can be distinguished at 

 fairly close range by decidedly shorter, stouter and thicker bill. 

 When at rest a prominent and distinctive character is the bluish- 

 white line along edge of upper mandible, and on land alternating 

 bands of yellow and black on feet can be distinguished with 

 binoculars. In flight lower surface appears pure white with no 

 sign of striation on flanks. Notes similar to those of Common 

 -Guillemot. (F.C.R.J.) 



vol. n. 3 f 



