BRITAIN'S BIRDS AND THEIR NESTS. 9 



ankles are at first sight mistaken for knees. The upright 

 position is also the one in which the Guillemot incubates, 

 standing astride of the egg, and generally facing the cliff. 

 On the wing the Guillemot could never be called 

 clumsy, seeing that the flight is direct and swift ; but it 

 is incapable of turning sharply, or of remaining poised on 

 motionless wings even for a second ; rapid, regular, and 

 unceasing wing-beats are characteristic. Generally it flies 

 a few feet above the waves, often in small parties flying 

 in single file, the birds so close together as to appear to 

 be almost touching. When leaving a high cliff the 

 Guillemot first makes a steep descent to its accustomed 

 level, and at that level seeks its destination. Of swim- 

 ming, diving, and swimming under water the Guillemot 

 is a past master. When swimming under water the wings 

 are used, and a considerable speed is attained. 



The single egg is large and pear-shaped, but is chiefly 

 remarkable on account of the extraordinaiy amount of 

 variation in colour to which it is subject. To begin 

 with, the ground may be of almost any colour, but 

 green tints are the commonest, from pale greenish white 

 to deep blue-green. The markings may take the form of 

 spots, blotches, or scroUings, and be black, reddish brown, 

 or greenish yellow in colour, or they may be of more than 

 one kind or one colour on the same egg. They may be 

 large or small, evenly distributed or collected in zones or 

 patches, few in number, or so abundant as almost com- 

 pletely to obscure the ground-colour. Each individual 

 female probably always lays eggs of the same type, for it 

 has been proved that when robbed of its first egg a 

 Guillemot will lay a similar one the same season. 



It is usually in cases where three or four eggs form 

 the clutch that eggs are markedly pear-shaped — as in 

 'Waders,' for example. In such cases the shape serves 



B 



