carrion-feeder. On the west coast of Patagonia, among the
thickly-wooded islets and broken land, it lives exclusively on what the
sea throws up, and on the carcasses of dead seals. Wherever these
animals are congregated on the rocks, there the vultures may be seen.
The Gallinazo (Cathartes atratus) has a different range from the last
species, as it never occurs southward of lat. 41 degs. Azara states
that there exists a tradition that these birds, at the time of the
conquest, were not found near Monte Video, but that they subsequently
followed the inhabitants from more northern districts. At the present
day they are numerous in the valley of the Colorado, which is three
hundred miles due south of Monte Video. It seems probable that this
additional migration has happened since the time of Azara. The
Gallinazo generally prefers a humid climate, or rather the
neighbourhood of fresh water; hence it is extremely abundant in Brazil
and La Plata, while it is never found on the desert and arid plains of
Northern Patagonia, excepting near some stream. These birds frequent
the whole Pampas to the foot of the Cordillera, but I never saw or
heard of one in Chile; in Peru they are preserved as scavengers. These
vultures certainly may be called gregarious, for they seem to have
pleasure in society, and are not solely brought together by the
attraction of a common prey. On a fine day a flock may often be
observed at a great height, each bird wheeling round and round without
closing its wings, in the most graceful evolutions. This is clearly
performed for the mere pleasure of the exercise, or perhaps is
connected with their matrimonial alliances.
I have now mentioned all the carrion-feeders, excepting the condor, an
account of which will be more appropriately introduced when we visit a
country more congenial to its habits than the plains of La Plata.
In a broad band of sand-hillocks which separate the Laguna del Potrero
from the shores of the Plata, at the distance of a few miles from
Maldonado, I found a group of those vitrified, siliceous tubes, which
are formed by lightning entering loose sand. These tubes resemble in
every particular those from Drigg in Cumberland, described in the
Geological Transactions. [10] The sand-hillocks of Maldonado not being
protected by vegetation, are constantly changing their position. From
this cause the tubes projected above the surface, and numerous
fragments lying near, showed that they had formerly been buried to a
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