312 THE NESTS AND EGGS OF 



Breeding habits: Brunnich's Guillemot is a nomadic 

 migrant, and wanders little south of open water during 

 winter, retiring north again as soon as the Polar seas 

 are free from ice. It is a gregarious bird, and breeds in 

 colonies, some of these nesting places being tenanted 

 by vast numbers of birds. Probably it pairs for life, as 

 season after season the same haunts are frequented. 

 Like the Common Guillemot the present sub-species 

 breeds on the ledges of the cliffs that overhang the sea, 

 gathering at the old accustomed places in May and 

 June. Its habits are not known to differ in any im- 

 portant respect from those of the southern race. It 

 makes no nest, and lays its eggs on the ledges and in 

 the hollows on the shelves of the beetling cliffs. When 

 disturbed at the colony the birds leave the cliffs in 

 streams, and resort to the water below, making no 

 demonstration of alarm, or showing any resentment at 

 the intrusion of their haunts. 



Range of egg colouration and measurement : 

 Brunnich's Guillemot lays only one ^^"g^ but if this be 

 taken, it is usually replaced several times in succession. 

 It covers precisely the same range of colour variation 

 as that of the Common Guillemot, fully described in 

 Nests and Eggs of British Birds, p. 311. Average 

 measurement, 3*2 inches in length, by 2*2 inches in 

 breadth. Incubation is performed by both sexes, but 

 the duration of the period is undetermined. Possibly 

 this may be slightly different from the period occupied 

 by the Common Guillemot, when we bear in mind the 

 much colder climate in which the ^ggs are hatched. 



Diagnostic characters: The eggs of Brunnich's 

 Guillemot cannot be distinguished from those of the 

 Common Guillemot in colour, but are generally broader 

 and blunter in shape. The locality is also of some 

 service in correctly identifying them. 



