2 34 British Birds, with their Nests and Eggs. 



manner of flight is peculiar and dissimilar to that of any Gull, consisting as it 

 does of five or six quick beats, followed by a graceful gliding motion. This 

 exercise is varied by many beautiful curvettes, none usually executed over the 

 sea at a greater probable elevation than some forty feet. Yet the birds which 

 hover so closely over the bosom of the deep at times ascend in the air to an 

 elevation of many hundred feet, as for example when the individuals which nest 

 in the interior of Rum return to their well-nigh inaccessible burrows among the 

 mountain-crags of that island deer-forest. Their choice of so remote a breeding 

 station is the more curious when we remember that some of the same birds nest 

 on a grassy cliff immediately overhanging the sea upon the east side of the island. 

 The Manx Shearwater appears to be principally a summer and autumn 

 visitor to our shores. Although I have handled numerous specimens in the flesh, 

 and seen many hundreds in life, between May and October, I have never yet 

 examined a Shearwater procured in Scottish waters during the winter months. 

 The breeding birds leave their island resorts between August and October, and 

 become veritable wanderers, journeying incessantly over the open sea, until a 

 rising temperature inspires them to return to their summer homes. In autumn, 

 and to a lesser degree in spring, they visit the east and south coasts of 

 Britain on migration. It is at such times as these that strayed individuals are 

 washed up dead on our foreshores, or stranded far inland. The title of 

 " Mackerel- cock " is sometimes applied to this Shearwater by sea- faring men. 

 The chick is at first invested with a covering of delicate grey down, which 

 covers the entire surface except the breast, the down of which is usually white, 

 or grey ringed with white. The nestling down is early replaced by a black and 

 white garb, which is worn by adults and young indifferently. A nestling from 

 Skomer, which still retains a patch of down upon the belly, has the crown and 

 upper parts black ; chin white ; sides of the breast washed with grey ; abdomen 

 and under tail-coverts white, except the outer feathers, which are varied with 

 black, which forms two black patches behind the thighs. An adult is similar, 

 but purer in tint. The bill is greyish-black ; irides dark-brown ; tarsus pale 

 grey, a black stripe shooting along the outer side of tarsus and outer toe ; the 

 remaining toes and webs grey, the latter tinged with black. The Manx Shear- 

 water measures about 14 inches in length; wing, 9.5 inches. 



