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 greater depth. Four
sets entered the sand perpendicularly: by working with