90 THE INFANCY OF ANIMALS 



clean-picked skeletons with only the quill-feathers sticking 

 to the wing-bones. . . . We soon discovered that one great 

 cause of the wholesale destruction of young birds was the 

 voracity of swarms of large hermit crabs {Cxnobita), for 

 again and again we found recently killed birds in all the 

 beauty of their first speckled plumage being torn to pieces 

 by a writhing pack of these ghostly crustaceans. There were 

 plenty of large ocypode crabs too aiding in the carnage." 



Moseley, in his " Notes of a Naturalist on the Challenger" 

 in like manner makes mention of a grapsus crab that he 

 saw on St. Paul's Rocks carrying off a newly-hatched 

 ■■-*tern ; " but such an accident does not shock one's feehngs 

 nearly so much," he remarks, " as does the thought of 

 full-grown young birds, nearly ready to fly out into the 

 world and to exercise their intelligence, being overpowered 

 by force of numbers and slowly eaten alive by animals 

 so far inferior in the scale." But curiously enough, the 

 nestlings of the booby {Sula leucogaster) and of the noddies 

 {Anous stolidous and A. melanogaster) living in the same 

 area as these unfortunate terns, defended themselves 

 vigorously and successfully from similar attacks. 



Nestlings of migratory species have yet another peril 

 to face : their first attempt to convert into action the 

 promptings of the migratory instinct. That large numbers 

 annually fail in this is certain : many wander out of their 

 course — from a defective instinct — as is shown by the fact 

 that the majority of the very " rare " birds, which reach our 

 shores are immature. Many fail in endurance and fall into 

 the sea. But no inconsiderable proportion of late broods 

 of young, every year, having attained the fledgeling stage, 

 are abandoned by their parents before they are able to 

 fend for themselves. And this because these parents find 

 the call to migrate irresistible. 



