YOUNG BIRDS IN THE NURSERY 89 



which in many parts has been profoundly modified in 

 response to the demands of this strenuous Hfe. Some 

 day, some inquiring student will make an effort to discover, 

 in the bodies of the victims who have perished, some 

 indication at any rate of the standard necessary to 

 survival, when a new chapter on the evidences of " natural 

 selection " will have to be written. 



On the whole, young reared in nurseries on the ground 

 suffer a higher death-rate than those reared in nests afford- 

 ing more shelter from adverse conditions, whether im- 

 posed by the animate or inanimate environment. Some 

 indication of the truth of this is borne in upon us every 

 now and then by cases of an exceptional and striking 

 character. A few such may be cited here by way of 

 example. Thus, Mr. Ogilvie Grant, when exploring the 

 Salvage Islands, found innumerable nestlings of the frigate 

 petrel (Pelagodroma marina) killed by mice, which had 

 eaten out the victim's brain ; and sucked eggs were even 

 more numerous. 



The introduction of pigs by settlers has wrought havoc 

 among birds in many parts of the world. Thus Moseley, 

 on his visit to Inaccessible Island, in his capacity of 

 naturahst to the Challenger Expedition, found that 

 feral pigs had nearly exterminated a penguin rookery on 

 the south side of the island ; but a few penguins remained 

 which had saved themselves by building in holes under 

 stones, where the pigs could not reach them. 



Dr. Alcock, in his dehghtful book " A Naturalist in 

 Indian Seas," relates a truly gruesome story. When 

 landing on Pitti Island, in the Laccadive Sea, he found 

 every foot of the ground above high-water-mark literally 

 carpeted with young terns of two species, many living and 

 full-fledged, many dead and rotting, and many reduced to 



