40 BIRDS OF LA PLATA 
dealing it blows with the beaf¥ hopping briskly about 
it all the time, apparently to guard themselves with 
their wings. They prey largely on the common 
Coronella anomala, but I have never seen one at- 
tacking a venomous species. When they have young 
many individuals become destructive to poultry, 
coming about the houses and carrying off the chickens 
and ducklings by day. In seasons of plenty they 
destroy far more prey than they can devour; but 
in severe winters they come, apparently starving, 
about the houses, and will then stoop to carry off 
any dead animal food, though old and dried up 
as a piece of parchment. This I have often seen 
them do. 
Though the Owls are always on familiar terms 
with the Vizcachas (Lagostomus trichodactylus) and 
occasionally breed in one of their disused burrows, 
as a rule they excavate a breeding-place for them- 
selves. The kennel they make is crooked, and varies 
in length from four to twelve feet. The nest is placed 
at the extremity, and is composed of wool or dry 
grass, often exclusively of dry horse-dung. The 
eggs are usually five in number, white, and nearly 
spherical; the number, however, varies, and I have 
frequently found six or seven eggs in a nest. After 
the female has begun laying the birds continue 
carrying in dry horse-dung, until the floor of the 
burrow and a space before it is thickly carpeted with 
this material. The following spring the loose earth 
and rubbish is cleared out, for the same hole may 
serve them two or three years. It is always untidy, 
