The habits of the spotted munia are those of the amadavat. Like the latter, it seems to thrive in captivity; it also loves warmth, and likes to go to roost with a warm companion on each side of it. Red and spotted munias live together very amicably in a cage; but as the latter, owing to their less showy plumage, are usually in a minority, they have to be content with outside positions at roosting-time. Sometimes my munias take it into their tiny heads to sleep on a perch which runs across a corner of the cage, and is barely long enough to accommodate them all. There are several other finer and longer perches, but, for some reason or other, they seem to prefer this one. Possibly its breadth is better adapted to the grip of their feet than that of any of the others. I may here say, in parenthesis, for the benefit of those who keep cage birds, that every cage should contain several perches of varying diameter, so as to permit the inmates of the cage the luxury of a change of grip.
Well, when a dozen birds persist in roosting on a perch intended only to seat ten, at least one of them is unable to find room on the perch, and is obliged either to sleep on the backs of some of his companions or make-believe that he is roosting on the perch. This latter feat is accomplished by the bird clutching hold of the two wires between which the perch passes and maintaining himself at an angle of 45° with the vertical. In this attitude a bird will sometimes sleep! Of course, its body is in part resting on that of its neighbour, but, allowing for this, a more uncomfortable position is inconceivable to a human being. The spotted munia, however, seems to find it tolerably comfortable.
Birds sleep standing, often on one leg. Did this require any appreciable muscular effort on the part of the bird there could be no rest in such an attitude, and the bird would fall off its perch as soon as it went to sleep. As a matter of fact, the muscles and tendons of a bird’s hind-limb are so arranged that, to use the words of Mr. F. W. Headley, “when the leg bends at the ankle, there is a pull upon the tendons, the muscles are stretched, the toes are bent and grasp the perch on which the bird sits. Thus he is maintained by his own weight, which bends the leg and so causes the toes to grip.” Thanks to this feature of their anatomy, passerine birds are able to sleep on branches of trees out of reach of prowling beasts of prey.