ARE FOOD TO BIRDS. 27 



least a portion of their subsistence from them. * The pied 

 oyster-catcher receives its name from the circumstance of 

 feeding on oysters and limpets (Patella vulgata), and its bill 

 is so well adapted to the purpose of forcing asunder the valves 

 of the one, and of raising the other from the rock, that " the 

 Author of Nature," as Derham says, " seems to have framed 

 it purely for that use." Several kinds of crows likewise prey 

 iipon shell-fish, especially upon the fresh-water mussels, and 

 the manner in which they force the stronghold of their vic- 

 tims is very remarkable. A friend of Dr. Darwin's saw above 

 a hundred crows, on the northern coast of Ireland, at once, 

 preying upon mussels. Each crow took a mussel up in the 

 air twenty or forty yards high, and let it fall on the stones, 

 and thus broke the shell. Many authorities might be adduced 

 in corroboration of this statement.! In Southern Africa so 

 many of the Testacea are consumed by these and other birds, 

 as to have given rise to an opinion that the marine shells 

 found buried in the distant plains, or in the sides of the moun- 

 tains, have been carried there by their agency, and not, as is 

 generally supposed, by eruptions of the sea. Mr. Barrow, 

 who is of this opinion, tells us, in confirmation of it, that 

 " there is scarcely a sheltered cavern in the sides of the moun- 

 tains that arise immediately from the sea, where living shell- 

 fish may not be found any day of the year. Crows even, and 

 vultures, as well as aquatic birds, detach the shell-fish from 

 the rocks, and mount with them into the air : shells thus 

 carried are said to be frequently found on the very summit 

 even of the Table Mountain. In one cavern at the point of 

 Mussel Bay," he adds, " I disturbed some thousands of birds, 

 and found as many thousands of living shell-fish scattered on 

 the surface of a heap of shells, that for aught I know, would 

 have filled as many thousand waggons." j The story, there- 

 fore, of the ancient philosopher whose bald pate one of these 

 unlucky birds mistook for a stone, and dropped a shell upon 

 it, killing at once the sage and cracking the oyster, is not so 

 tramontane as to stumble all belief ! 



Land shells furnish a few birds with part of their susten- 

 ance, and the principal of these are two well-known songsters, 

 the blackbird and the thrush. They, 



" whose notes 



Nice finger'd Art must emulate in vain,' 



* "The abundance of shell-fish in Conception entices a great many birds 

 within the bay." — Beechy's Voyage, i. 31. 



t Blackwalhs Research, in Zoology, 154-5. 



X Travels in Southern Africa, i. 8.— On the summit of the chain of moun- 

 tains which border the Icy Sea, " to the east of Simovic Rctchinoie, is an 



