340 THE BIRDS OF THE BRITISH ISLES. 



The white croup or lower back of the Rock-Dove is its best 

 character, but the two black bars on its pale-grey wing are 

 distinct ; the tail is margined with white. It is strong and 

 quick on the wing, dashing out from the caves, flying low over 

 the water, its white rump showing well from above. Little 

 parties will circle over the sea and the cliff tops, when the white 

 under wing is equally conspicuous ; in its flight, behaviour, and 

 voice, which is more of a dovecot coo than the phrase of the 

 Ring-Dove, it shows its relationship. Though fields are visited 

 for grain and green food, it is nowhere so plentiful as to be 

 a pest, and the good it does by devouring weeds probably 

 balances the damage. Like other pigeons it often drinks ; I 

 have seen it alight on the sea, and apparently drink salt water ; 

 domestic birds will alight on water, even on the sea. The 

 bowing courtship, when the metaUic lustre of the neck is fully 

 displayed, often takes place on ledges where Guillemots and 

 Razorbills sit. 



The nest is usually on a ledge in a cave ; it is a slight 

 structure of grass, heather, or seaweed. The two white eggs, 

 more like those of the Ring-Dove than the Stock, measure 1*5 

 by 1*1 inches. The nestling has pale yellow down and a flesh- 

 coloured bill with a dark band. It is tended and fed on 

 " milk " like other doves. 



The head and neck of the mature bird are a darker blue-grey 

 than the back and wings ; the lower back is white. The green 

 and lilac or purple patch on the side of the neck is larger than 

 that of the Stock, and the tail is more distinctly banded. The 

 bill, legs, and irides are as in the Ring-Dove. Young birds 

 show little lustre and are duller. Length, 13-5 ins. Wing, 

 8-5 ins. Tarsus, i'2 ins. 



Turtle-Dove. Streptopelia hirtiir (Linn.). 



The migratory Turtle-Dove (Plate 150) has a western Palas- 

 arctic range, though it is rare in northern Scandinavia and 



