224 A HISTORY OF BIRDS 



and for a long 'while are utterly unable to leave the nest or to 

 feed themselves. 



It is curious that while parental responsibilities of a com- 

 plex character are undertaken even among the lowest inverte- 

 brates, the practice of feeding the young obtains only with the 

 ants and bees among the invertebrates, and is not met with 

 again till we come to the birds and the Mammalia. 



The labour entailed in this among the birds varies with the 

 nature of the food required and its preparation. The active 

 young of graminivorous birds, such as the Game-birds for in- 

 stance, or of the Plover tribe, which feed upon small Crustacea, 

 snails, worms and so on, or of the Duck tribe, which live upon 

 vegetable matter and small animal organisms, follow their 

 parents to feed under their direction. But where, as in the 

 case of the Grebes, for example, the food is obtained only by 

 chase, and for the most part by diving, the young swim out 

 after the parents, and are fed by them on a diet consisting of 

 very small fish, Crustacea and a small quantity of vegetable 

 matter. 



The Dabchick or, Little Grebe {Tachybaptes fluviatilis), how- 

 ever, appears to differ from its larger relative in this matter, 

 in that the young remain for many hours daily in the nest 

 perched on the back of the mother and covered by her wings, 

 and during this time are assiduously fed by the male, who 

 has been seen to make as many as forty journeys with food in 

 the space of a little less than an hour. Later, as the young 

 gather strength, they are fed on the water, the diet being 

 at least partly vegetable. The food appears to be dropped on 

 the water and picked by the youngsters. 



The Sand-grouse afford perhaps one of the most remarkable 

 instances yet discovered of the care displayed by birds for 

 their offspring. These birds are dwellers in arid deserts and 

 consequently have to make long journeys night and morning 

 to procure water. During the time that the young are helpless 

 their drinking water is supplied by the cock, and this in an 

 absolutely unique fashion. After having slaked his thirst at 

 the customary drinking pool, generally many miles distant from 

 the feeding ground and young, he proceeds to wallow in the 

 water after the fashion of a bird dusting its plumage, remaining 

 until the feathers of the under parts are thoroughly saturated. 



