NIGHTJAR. 381 



it may be heard by day even at noontide, but it is then de- 

 livered drowsily, as it were, and without the vigour that 

 characterizes its crepuscular or nocturnal performance. On 

 the wing while toying with his mate, or executing his rapid 

 evolutions round the trees where both find their food, the 

 cock occasionally produces another and equally extraordinary 

 sound, which by some excellent observers has been called a 

 squeak, but to the writer is exactly like that which can be 

 made by swinging a whip-thong in the air. How the bird 

 produces this sound is unknown, but it often accompanies a 

 sudden change in the direction of flight, and especially a 

 sudden shooting aloft which ends in a downward glide. 

 When disturbed from rest, something of the same kind may 

 also be often heard, but then it would seem to be the result 

 of smiting the wings together, though at other times the 

 flight is noiseless. Among the many agreeable occupations 

 which so frequently gratify the lover of Nature, not the least 

 is that of watching the behaviour of Nightjars on a summer's 

 evening, especially if they be engaged in seeking their food 

 near the ground, as they not unfrequently do.* Their com- 

 mand of wing is very great, and the rapid twists they make 

 in quest of active prey, rendering them alternately invisible 

 in the gathering shades and then conspicuous against the 

 fading light adds a mysterious charm to their silent Sittings, 

 for the spectator never knows in what quarter to expect one 

 of them to appear, and indeed is apt to exaggerate the num- 

 ber of birds around him. The common opinion that the 

 Nightjar always flies open-mouthed is not confirmed by such 

 observations as circumstances permit, and, as Macgillivray 

 has well remarked, would seem to be unreasonable. The 

 wide gape can doubtless be instantaneously opened and shut, 



* Some dogs delight to hunt field-mice in the meadows at nightfall. "When so 

 employed their movements disturb a considerable number of moths, and the 

 Nightjar, thereby attracted, will keep hovering over the dog's head, and eagerly 

 seize every moth that takes wing. Mr. R. Gray says that he has seen this bird 

 " in grass fields cleverly picking ghost moths (Hepialus humuli) off the stems, 

 from the points of which these sluggish insects were temptingly hanging." The 

 Editor, however, has never observed the Nightjar take any prey that was nob 

 flying, though it has been said to eat caterpillars, slugs and other small mollusks, 

 as well as young frogs and their spawn (Bailly, Orn. Savoie, i. pp. 220, 221) ! 



