BUFFON'S OR LONGTAILED-SKUA 227 



principal food in this district was the fruit of the crowberry 

 (Empdrum nigrum), large beetles, and Crustacea, and the young birds 

 never contained anything except crowberries. 1 Lieutenant S. A. 

 Davies found that on the moors near the Muonio river, the 

 young were apparently fed on decaying lemmings : quite a store 

 of these mammals was heaped up beside each nest in various 

 stages of decomposition, and the smell of the old birds was very 

 offensive. 



The nest is a shallow depression in the ground, sometimes 

 natural and sometimes made by the bird, sparingly lined with a few 

 withered grasses or a leaf or two of Salix. It is placed on the open 

 tundra, but always close to water, though it may be only a tiny pool or 

 an accumulation of melted snow. The eggs are normally two in 

 number, though instances in which only one has been found incubated, 

 or a single young bird only reared, are not uncommon. On one or two 

 occasions three eggs have also been found in one nest. They are on 

 an average more elongated and narrower than those of Richardson's 

 skua, though at times indistinguishable, while some beautiful varieties 

 are occasionally met with, in which the ground-colour is pale blue or 

 greenish blue, and without or almost without markings. Most eggs, 

 however, vary from umber to olive-brown in ground-colour, with rather 

 scanty spots, streaks, and blotches of deep umber-brown, and purplish 

 grey shell-markings. The average size of 56 eggs is 2'21 x 1/52 in. 

 [56'3 x 38'8 mm.]. From 36 to 48 or even 50 hours elapse between the 

 laying of the first and second eggs, and there is a corresponding 

 difference in the period of emergence from the egg, so that it is 

 evident that incubation begins with the laying of the first egg. During 

 the period of incubation, which, according to Manniche, lasts for 

 twenty-three days, both sexes take turns upon the eggs, the non-sitting 

 bird keeping a vigilant watch over its mate. The attitude of the 

 sitting bird is upright, the head being held high as though the bird were 

 on the alert, and the yellowish throat and white breast, contrasting 



1 [H. W. Wheelwright], A Spring and Summer in Lapland, 1st ed., p. 357. 

 VOL. III. 2 G 



