Page:Popular Science Monthly Volume 76.djvu/560

556 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. 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:

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.