372 THE NIGHTJAR 



head, and without making any visible movement, must be of undoubted 

 value to the species. The same birds, when alarmed, used to com- 

 press their feathers. A photograph shows one of them in this position 

 on the ground. The top of the head is in a line with the body, the 

 beak horizontal, and the eyelids partly open. A bird, observed in 

 the wild state, when alarmed on the nest adopted the same attitude, 

 with the difference that she turned the beak upward. The nestling 

 in down did the same. The compression of the feathers is not, of 

 course, peculiar to the nightjar. It is frequently observed in the case 

 of birds that are startled or alarmed, whether they be sitting in a 

 nest or standing. 



The coloration of the nightjar's plumage serves to protect 

 not only its eggs, but no doubt also the bird itself, for, when sur- 

 prised in a drowsy state during the day, it would probably find it 

 no easy task to escape by flight from the swoops of the faster birds 

 of prey. From animals, like the fox and stoat, that hunt by smell it 

 would be protected by the fact that it seldom moves any distance 

 upon the ground, and so leaves little or no trail. 



What renders a protective coloration so necessary to the nightjar 

 is its habit of laying its eggs on the bare ground, and not under 

 cover, unless there be round the nest bracken or other vegetation 

 which has had time to grow up, as is often the case later in the 

 season. Why the bird does this is beyond my ability to explain. It 

 may be that, having in the last resort to save itself by flight, it profits 

 by not being in a confined space, with obstructions probably on every 

 side except one, and that side in possession of the enemy. The same 

 danger would face all the weaker animals that rear their young in 

 holes, except those that have an emergency exit, or scent danger from 

 afar. 



Incubation is to some extent shared by the male nightjar. 

 Dr. Heinroth's captive male took the female's place upon the eggs 

 for a time in the morning, at midday, and in the evening. At 

 night it was the female that sat, a fact ascertained by attaching 



