FOOD OF NIGHTJARS 31 



open their beaks, even in broad daylight, when they 

 were obviously hawking for insects. The point is 

 an important one, I think, in considering what kinds 

 of insects the nightjar more habitually feeds on, 

 and how, in general, it procures them — questions 

 which, having been settled, as it seems to me, 

 merely by assertion, are entirely reopened by the 

 fact that the young are fed in the way I have 

 described. For if moths and cockchafers are the 

 bird's principal food, why should it not bring these 

 to the young, in the ordinary way ? But if it 

 swallows huge quantities of insects, so small that 

 it cannot seize them in the bill, but must engulf 

 them, merely, as it flies, as a whale does infusoria, 

 we can then see a reason for its not doing so. How 

 else, but by disgorging it in the form of a pulp, 

 could such food as this be given to the chick ^ and 

 if to do so became the bird's habitual practice, it 

 would not be likely to vary it in any instance. 

 Now the green woodpecker feeds largely on ants, 

 and, further on, I will give my reasons for believing 

 that it feeds its young by regurgitation. The little 

 woodpecker, however, I have watched coming, time 

 and time again, to its hole in the tree-trunk, with 

 its bill full of insects of various kinds, and of a 

 respectable size, so that there is no doubt that it 

 gives these to its brood, as does a thrush or a black- 

 bird. What can make a diff^erence, in this respect, 

 between two such closely-allied species, if it be not 

 that the one has taken to eating ants, minute crea- 

 tures which it has to swallow wholesale, and could 

 not well carry in the bill ? When, therefore, we 

 find the parent nightjar regurgitating food into the 



