and receive the food their parents bring; when approached they become irritated, snapping with their beaks, and retreat reluctantly into the hole; and for some weeks after leaving it they make it a refuge from danger. Old and young birds sometimes live together for four or five months. I believe that nine-tenths of the Owls on the pampas make their own burrows, but as they occasionally take possession of the forsaken holes of mammals to breed in, it is probable that they would always observe this last habit, if suitable holes abounded, as on the North-American prairies inhabited by the marmot. Probably our Burrowing-Owl originally acquired the habit of breeding in the ground in the open level regions it frequented; and when this habit (favourable as it must have been in such unsheltered situations) had become ineradicable, a want of suitable burrows would lead it to clean out such old ones as had become choked up with rubbish, to deepen such as were too shallow, and ultimately to excavate for itself. The mining instinct varies greatly in strength, even on the pampas. Some pairs, long mated, only begin to dig when the breeding-season is already on them; others make their burrows as early as April--that is six months before the breeding-season. Generally both birds work, one standing by and regarding operations with an aspect of grave interest, and taking its place in the pit when the other retires; but sometimes the female has no assistance from her partner, and the burrow then is very short. Some pairs work expeditiously and their kennel is deep and neatly made; others go about their task in a perfunctory manner, and begin, only to abandon, perhaps half a dozen burrows, and then rest two or three weeks from their unprofitable labours. But whether industrious or indolent, by September they all have their burrows made. I can only account for Azara's unfortunate statement, repeated since by scores of compilers, that the Owl never constructs its own habitations, by assuming that a century ago, when he lived and the country was still very sparsely settled, this Owl had not yet become so abundant or laid aside the wary habit the aborigines had taught it, so that he did not become very familiar with its habits. 291. GLAUCIDIUM NANUM (King). (PYGMY OWL.) +Glaucidium nanum+, _Scl. et Salv. Nomencl._ p. 117; _Burm. La-Plata Reise_, ii. p. 441; _Scl. P. Z. S._ 1872, p. 549 (Rio Negro); _White, P. Z. S._ 1883, p. 41 (Cordova); _Döring, Exp. al Rio Negro_, p. 49 (Rio Negro); _Sharpe, Cat. B._ ii. p. 190.