During the inclement winter of Buenos Ayres the Guira Cuckoo is a miserable bird, and appears to suffer more than any other creature from cold. In the evening the flock, usually composed of from a dozen to twenty individuals, gathers on the thick horizontal branch of a tree sheltered from the wind, the birds crowding close together for warmth, and some of them roosting perched on the backs of their fellows. I have frequently seen them roosting three deep, one or two birds at the top to crown the pyramid; but with all their huddling together a severe frost is sure to prove fatal to one or more birds in the flock; and sometimes several birds that have dropped from the branch stiff with cold are found under the trees in the morning. If the morning is fair the flock betakes itself to some large tree, on which the sun shines, to settle on the outermost twigs on the northern side, each bird with its wings drooping, and its back turned towards the sun. In this spiritless attitude they spend an hour or two warming their blood and drying the dew from their scanty dress. During the day they bask much in the sun, and towards evening may be again seen on the sunny side of a hedge or tree warming their backs in the last rays. It is owing, no doubt, to fecundity, and to an abundance of food that the Guira Cuckoo is able to maintain its existence so far south in spite of its terrible enemy the cold. With the return of warm weather this species becomes active, noisy, and the gayest of birds; the flock constantly wanders about from place to place, the birds flying in a scattered desultory manner one behind the other, and incessantly uttering while on the wing a long complaining cry. At intervals during the day they also utter a kind of song, composed of a series of long modulated whistling notes, two-syllabled, the first powerful and vehement, and becoming at each repetition lower and shorter, then ending in a succession of hoarse internal sounds like the stertorous breathing of a sleeping man. When approached all the birds break out into a chorus of alarm, with notes so annoyingly loud and sustained, that the intruder, be it man or beast, is generally glad to hurry out of ear-shot. As the breeding-season approaches they are heard, probably the males, to utter a variety of soft low chattering notes, sounding sometimes like a person laughing and crying together: the flock then breaks up into pairs, the birds becoming silent and very circumspect in their movements. The nest is usually built in a thorn-tree, of rather large sticks, a rough large structure, the inside often lined with green leaves plucked from the trees. The eggs are large for the bird, and usually six or seven in number; but the number varies greatly, and I have known one bird lay as many as fourteen. They are elliptical in form and beautiful beyond comparison, being of an exquisite turquoise-blue, the whole shell roughly spattered with white.