BANK-MARTIN 39 
laria)—have everywhere afforded the Martins abun- 
dance of breeding-places on the plains, even where 
there are no streams or other irregularities in the 
smooth surface of the earth. 
The Minera bores its hole in the sides of the 
Vizcacha’s great burrow, and in this burrow within 
a burrow the Martin lays its eggs and rears its young, 
and is the guest of the Vizcacha and as much depen- 
dent on it as the House-Wren and the Domestic 
Swallow on man; so that in spring, when this 
species returns to the plains, it is in the villages of 
the Vizcachas that we see them. There they live and 
spend the day, sporting about the burrows, just as 
the Common Swallow does about our houses; and 
to a stranger on the pampas one of these villages, 
with its incongruous bird and mammalian inhabi- 
tants, must seem a very curious sight in the evening. 
Before sunset the old male Vizcachas come forth to 
sit gravely at the mouths of their great burrows. 
One or two couples of Mineras, their little brown 
bird-tenants, are always seen running about on the 
bare ground round the holes, resting at intervals 
with their tails slowly moving up and down, and 
occasionally trilling out their shrill laughter-like cry. 
Often a pair of Burrowing-Owls also live in the 
village, occupying one of the lesser disused burrows ; 
and round them all flit half a dozen little Martins, 
like twilight moths with long black wings. It is 
never quite a happy family, however, for the Owls 
always hiss and snap. at the Vizcacha if he comes 
too near; while the little Martins never become 
