RICHARDSON'S SKUA. I21 



the invariable greater length of the toe and claw than the tarsus is a characteristic 

 of Stercorarins. 



Richardson's Skua builds in groups, scarcely to be called colonies, with their nests 

 set a considerable distance from each other : on heaths far from the sea ; in a hollow 

 amongst hills ; in low, wet, mossy heaths, in exposed situations ; in Caithness, " a 

 low and remote piece of moorland, studded by numbers of small lakes, containing 

 mossy mounds and islands of varied size and shape" (Osborne). The nests are 

 shallow hollows in the ground, the heather, or the mossy mounds they affect, 

 about seven or eight inches in diameter, lined with dead leaves, sedges and grass. 

 The female lays two eggs, of a ground colour which varies from shades of green 

 to shades of brown, spotted, blotched or streaked with reddish- or blackish-brown 

 or purplish-grey ; sometimes sparsely distributed all over, or congregated toward 

 the larger end. They vary in length from 2I to 2\ inches, by ii to if in breadth. 

 They closely resemble specimens of the eggs of the Pomatorhine Skua, and of 

 the Common and other Gulls. It is easy to discover the nest of the Skua by the 

 behaviour of the parent birds. When the eggs are newly laid they do not seem 

 to have the same solicitude for them ; but when they are hard set, or when the 

 chicks are in the nest, they swoop down in a very menacing manner upon the 

 intruder. 



The young emerge covered with long, soft, sooty-grey down above, paler 

 beneath ; but the nestlings of the differently coloured parents vary much. 



The parents may be both dark ; or one dark and; the other white-breasted ; of 

 which either colour may be a male or a female. The young from the union of 

 these differently coloured parents are, when adult, intermediate in character, " having 

 a dusky whitish throat, more or less of an ash-brown on the flanks" (Saunders). 

 Mr. Dunn writes that he has taken the fully fledged young birds of a dark brown 

 colour, the parents of which were light breasted ; and, on the contrary, light 

 coloured young birds from dark coloured parents. 



Mr. Saunders describes the immature birds as streaked and mottled with 

 various shades of brown on the upper surface, the mantle chiefly umber ; upper 

 tail-coverts barred with dark brown, white or rufous ; the under surface more or 

 less barred with brown on a paler ground. 



The offspring of two white-breasted birds is pale cinnamon-brown on the head 

 and under parts, with dark streaks and bars; the feathers of the upper parts 

 umber-brown, with rufous edges. The offspring of two dark birds is much darker, 

 with greyer tips to the feathers ; while the offspring of one white- breasted and one 

 sooty bird is intermediate. 



The winter plumage of this bird is the same as that of the last species. 



