272 BRITISH SEA BIRDS. 



as they fly to and fro and in and out of their nests. 

 Then during the period of migration many Martins 

 pass along the sea-board, and sometimes the 

 observer may be fortunate enough to witness their 

 actual arrival from over the sea, or their final depar- 

 ture across its lonely expanse. 



ROCK DOVE. 



We here have another exclusively marine species, 

 the Columba livia, of Linnaeus and most modern 

 writers, confined to such portions of the coast as 

 are precipitous and full of caves and hollows. The 

 Rock Dove may be readily distinguished from all 

 the other British species of Pigeons by its white 

 lower back and rump, and strongly-barred wings. 

 As may naturally be inferred from the cliff-haunting 

 propensities of this Dove, it is practically absent 

 from the low-lying eastern coasts of England, local 

 on the south coast, but becomes much commoner 

 further north and west, where the cliffs are rugged 

 and lofty, and full of those wave- worn hollows and 

 fissures that are the Rock Dove's delight. As most 

 readers may be aware, this species is the original 

 stock from which the numerous races of dovecot 

 Pigeon have descended. Curiously enough, this 

 bird is inseparably attached to the coast ; it is a 

 rock-haunting species, and one which rarely or 

 never perches in trees. Usually our first acquaint- 

 ance with the Rock Dove is made as the startled 

 bird dashes out of the cliffs, with rattling wings and 



