NATURAL HISTORY SOCIETY OF GLASGOW. 123 



C. arcticus is about three to one of C. septentrionalis, and in the 

 north-east this is as nearly as possible reversed. Taking the 

 county as a whole, the two species are about equal in number. 



On each of the smaller lochs frequented by this species, only 

 one pair is to be found breeding, but on some of the larger lochs 

 two pairs are occasionally observed. The nest is simply a hollow 

 in the ground, rarely, if ever, having any lining, and chosen close 

 to the water edge, or at least within a yard of it. On several 

 occasions with a good glass I have watched the female as she sat 

 on her eggs, whilst the male swam up and down at no great 

 distance, and often close beside the island. As he did so, all 

 unsuspicious of my presence, he would gracefully dip his bill in 

 the water, or lie over on his side, stretching back his leg the 

 better to preserve his balance, and then preen the feathers of his 

 breast and side with his long dagger-shaped bill. When alarmed, 

 he would raise his head sharply, and gradually sink his body, till 

 his back became level with the water, or entirely disappeared 

 beneath it, leaving only the long snake-like neck and head ex- 

 posed to view. If the danger then became more imminent, he 

 would dive without leaving a ripple on the surface, and reappear 

 far out upon the loch. 



The cry of the Black-throated Diver, when alarmed, is a 

 guttural " quack," repeated at intervals, which seems to be a cry 

 of warning to the female. I have never seen the male bird quit 

 the water and rest upon land, though he not uufrequently rises 

 off the surface and flies once or twice round the loch, nor have I 

 seen the female on land save when she has been sitting on her 

 eggs. On leaving the nest, when undisturbed, she floats gently 

 off on the surface, but if alarmed, almost instantaneously dives, 

 or should the water close to shore be too shallow to admit of this, 

 she half flies, half swims, until she finds sufiicient depth, splash- 

 ing up the water, and making sufficient noise to be heard 250 

 yards off on a calm day. 



The Black-throated Diver seldom breeds on the shores of a 

 loch, although I have heard of well authenticated instances of its 

 doing so. It usually chooses a green, grass-grown island, and 

 should a loch be found not to possess such an island, it is almost 

 needless to search there for a Diver's nest. On one loch with 

 which I am acquainted, a pair of these birds breed upon a long 

 narrow point of gravel and sand, which runs out from a grassy 



