THE RULES OF THE ROOST 317 



The roosting -habits of birds display some interest- 

 ing variations. Generally in repose birds " tuck 

 their heads under their wings," as the popular 

 description of the action has it ; in reality the 

 bill or head rests between the basal joint of the 

 wing and the back, and is merely covered by the 

 adjacent shoulder-feathers. Some birds, however, 

 such as Owls and Penguins, very rarely assume this 

 position, and, as far as I have seen, Grebes and the 

 Ratite birds, with the exception of the Apteryx, 

 always keep the head to the front. Some birds 

 lie down when sleeping, such as the Game-birds, 

 the Cariama, and the Ratites, as well as many 

 waterfowl ; but others prefer to sleep standing 

 on one leg, such as Storks, Cranes, and Passerines. 

 Parrots and Owls rarely sit down, either by day or 

 night, and generally rest on both feet ; the diurnal 

 birds of prey also generally prefer a standing pose 

 at all times, with the exception of the American 

 Vultures, which sit down when at roost. 



The hold upon the perch, among those birds 

 which roost aloft, is maintained automatically by 

 the flexure of the toes which results on the bending 

 of the hock- joint, so that no effort is required ; 

 but the grip must be very slight in those perching 

 birds in which the hind toe is poorly developed, 

 as in the perching species of Ducks and in the 

 Cariama, which also has very short front toes. An 

 even more remarkable percher is a Demerara 

 Tinamou which, according to Waterton, has the 

 custom, unique, apparently, in its family, of sleeping 



