86 The Naturalist in La Plata, 
was in sight, and, squatting ab my feet, endeaYOiir 
to conceal themselves by thrusting their heads and 
long necks up my trousers. If I had caused a 
person to dress in white or yellow clothes for several 
consecutive days, and had then uttered the warning 
cry each time he showed himself to the birds, I 
have no doubt that they would soon have acquired a 
habit of running in terror from him, even wnthout 
the warning cry, and that the fear of a person in 
white or yellow would have continued all their lives. 
Up to within about twenty years ago, rheas were 
seldom or never shot in La Plata and Patagonia, 
but were always hunted on horseback and caught 
with the bolas. The sight of a mounted man would 
set them off at once, Avhile a person on foot could 
walk quite openly to within easy shooting distance 
of them ; yet their fear of a horseman dates only 
two hundred years back — a very short time, when 
we consider that, before the Indian borrowed the 
horse from the invader, he must have systematically 
pursued the rhea on foot for centuries. The rhea 
changed its habits when the hunter changed his, 
and now, if an estanciero puts down ostrich hunting 
on his estate, in a very few years the birds^ although 
wild birds still, become as fearless and familiar 
as domestic animals. I have known old and ill- 
tempered males to become a perfect nuisance on 
some estancias, running after and attacking every 
person, whether on foot or on horseback, that 
ventured near them. An old instinct of a whole 
race could not be thus readily lost here and there 
on isolated estates wherever a proprietor chose to 
protect his birds for half a dozen years. 
