556 THE POPULAR SCIENCE MONTHLY 



capped and primed, ready to go off as soon as some one pulls the trigger, 

 which is of the hair variety. When this instinct is ripe, the plucking 

 of a single leaf, or any unusual sight or sound will send all off in a 

 panic. They scatter in every direction, making flights both long and 

 good for a first effort, or, if less mature, down they all go flapping to 

 the ground and, if robbins, squealing their danger-signals in high-pitched 

 voices, indicative of that fear which shows in every attitude and note. 

 Correlation, however, is not always perfect, and in consequence of the 

 prematurity of fear many young birds flutter out of their nests in a 

 helpless condition, to meet certain destruction from their numberless 

 enemies on the ground. 



That fear in birds may be connate, or present at the time of birth, 

 seems to be clearly implied by an interesting experience reported by 

 Hudson. 5 He was fortunate in finding a nest of the La Plata jacana 

 (Parra jacana) on a small mound of earth in a shallow lagoon, with 

 four eggs the shells of which were already chipped. Dismounting from 

 his horse, he picked up one of the eggs and held it for a moment in the 

 palm of his hand, when, as he says : 



All at once the cracked shell parted, and at the same moment the young 

 bird leaped from my hand and fell into the water. I am quite sure that the 

 young bird's sudden escape from the shell and my hand was the result of a 

 violent effort on its part to free itself; and it was doubtless inspired to make 

 the effort by the loud screaming of the parent birds, which it heard while in 

 the shell. Stooping to pick it up to save it from perishing, I soon saw that my 

 assistance was not required, for immediately upon dropping into the water, it 

 put out its neck, and with the body nearly submerged, like a wounded duck 

 trying to escape observation, it swam rapidly to the second small mound I have 

 mentioned, and escaping from the water, concealed itself in the grass, lying 

 close and perfectly motionless like a young plover. 



In this remarkable case the whole complex of behavior is as plainly 

 expressive of fear at every step, as it is evidently the free gift of heredity. 



5 Hudson, W. H., "The Naturalist in La Plata," pp. 111-112, London, 1S92. 



