M A LD O N A D O . 1 8 3 2 - 3 .
always so call them. It is a cvwious circurastaDce that, when
cvyiiK’ out, they liirow their heads upwards and backwards,
after tiic same manner as the Carrancha. They build on
the rocky cliffs of the sea-coast, but only in the small islets,
and not in the two main islands. This is a singular precaution
in so tame and fearless a bird._ The sealers say that
the flesh of these birds when cooked, is quite white, and \ eiy
good eating. , nr i,-
We have now only to mention the turkey-buzzard (1 ¡din
aura), and the Gallinazo. The former is found ''Ferever
the countiT is moderately damp, from Cape Horn to North
America. Differently from the Polyborus Braziliensis and
Chimango, it has found its way to the Falkland Islands.
The turkey-buzzard is a solitary bird, or at most goes m
pairs. It may at once be recognised from a long distance,
bv its lofty, soaring, and most elegant flight. It is well
known to be a true carrion feeder. On the west coast of
Patarania, 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
conm-eo-ated on the rocks, there the vultures may be seen.
The Gallinazo [Catliartes atratus) has a different range from
the last species, as it never occurs to the^ southward of
lat. 41°. Azara states that there existed a tradition that these
birds, at the time of the conquest, were not to be found near
Monte Video, but that they subsequently followed the inhabitants
from more northern districts. At the preseiit 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, hut I never
saw or heard of one in Chile: in Peru they are preserved as
¡ 8 3 2 - 3 . CABlUON HAWKS. 6!)
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 done
for sport-sake, 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 generally supposed to
have been formed by lightning entering the loose sand.
These tubes resemble in every particular those from Drigg,
in Cumberland, described in the Geological Transactions.*
The sand-hillocks of Maldonado, not being protected by
Yegetation, 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 greater depth. Four sets entered the sand
perpendicularly : by working with my hands I traced one of
them two feet deep ; and some fragments which evidently
had belonged to the same tube, when added to the other
part, measured five feet three inches. The diameter of the
whole was nearly equal, and therefore we must suppose that
originally it extended to a much greater depth. These dimensions
are however small, compared to those of the tubes
from Drigg, one of which was traced to a depth of not less
than thirty feet.
The internal surface is completely vitrified, glossy, and
smooth. A small fragment examined under the micro-
* G eo lo g . T r a n s a e t., vol. ii,, p. 5 28,