The most remarkable feature connected with the habits of these birds is, however, connected with their nesting arrangements. As was first observed in India in 1855 by a military officer devoted to outdoor natural history, when the female has laid her clutch of eggs, varying in number from two to half a dozen, in some hole in a tree and commenced to incubate, the male walls up the entrance to the apartment with clay, leaving an aperture only just large enough for her to protrude her beak and receive the food brought regularly by her hard-working mate. The object of this immuring process is doubtless to protect the female and her eggs or young from the attacks of birds-of-prey, or predatory arboreal mammals. Under these circumstances sanitary matters cannot, of course, be attended to, and the nest-hole, consequently, soon becomes an evil-smelling mass of abominable filth. In order that no time may be wasted, the female moults during the period of her confinement, a process which adds still more to the mess in the hole. The young, which come forth from the eggs almost naked, remain in the breeding-hole till they are fully fledged. To reach the food brought by her partner, the female, at any rate during the early stages of incubation, has to climb up to the aperture in the wall of clay. THE BLUE MACAW (_Ara cærulea_ or _Ara ararauna_) The blue, or blue and yellow, macaw, the ararauna of the natives, is one of the most familiar representatives of a group of tropical American parrots characterised by their large size, long tails, and brilliantly coloured plumage, as well as, it may be added, by their atrociously loud, screaming cries, which render them among the most objectionable of all birds as pets. In the species forming the subject of the plate blue and yellow are the predominant hues; yellow, it is said, being the equivalent among true parrots, in which white is unknown, to no colour at all. The whole of the under surface and the sides of the neck are deep orange-yellow, while the upper surface, inclusive of the tail-coverts, is dark sky-blue. The range of this species, like that of its relative the green and blue macaw (_Ara severa_), extends only from Panama southwards through the tropical forests of the New World. Other kinds are, however, found farther north, the handsome red and blue species (_A. chloroptera_) and the red and green macaw (_A. militaris_) extending, for instance, from Mexico and central America to Bolivia. Four other species, known on account of their deep blue colouring, as hyacinthine macaws, constituting the genera _Anodorhynchus_ and _Cyanopsittacus_, are, on the other hand, solely Brazilian.