(CHOPI BOAT-TAIL.)
+Chopi+, _Azara, Apunt._ i. p. 282. +Aphobus chopi+, _Scl. Cat. B._
xi. p. 405. +Psarocolius unicolor+, _Burm. La-Plata Reise_, ii.
p. 494 (Mendoza).
_Description._--Uniform black, slightly resplendent; bill and feet
black; lower mandible sulcated: whole length 9·2 inches, wing 5·2,
tail 4·0. _Female_ similar, but smaller and duller; bill not
sulcated.
_Hab._ S. Brazil, Paraguay, Argentina, Bolivia, and Peru.
The Chopi, which is said to be quite common in Paraguay, is only found
in the north-eastern part of the Argentine Republic, consequently I have
never seen it, except as a cage-bird; nor is there anything about it in
the notes of recent collectors and travellers who have visited the upper
waters of the Plata. This is, however, not to be regretted, since
Azara gave a very full and spirited account of this species in his
'Apuntamientos;' although it certainly does seem strange that the Chopi
should have had two careful observers of its habits fully a century ago,
namely, Azara and his friend and fellow-naturalist the priest Noseda,
and not one since. Evidently Azara was very familiar with this bird, for
he describes it lovingly and at great length, his history of it being
one of the most charming things in his work. According to him the
Chopi is a highly sagacious bird, and although a frequent visitor to
courtyards and verandahs of houses in Paraguay, too shy and suspicious
to be caught with snares. It has a strong and easy flight, and readily
attacks any large bird passing near, following it persistently in
the air, or, pouncing down, fastens itself on its enemy's back. If
the Caracara Eagle (_Polyborus_) alights in order to shake off its
persecutor, the Chopi perches at a distance of a few feet, where it
assumes an indifferent manner; but no sooner does the Caracara allow its
attention to wander from its adversary, then it is again subjected to
fresh insult. These attacks on so large and powerful a species may be
regarded as mere impertinences, but by practising them the Chopi is soon
able to rid himself of the presence of any unwelcome bird. From a long
distance he recognizes an enemy, by its figure, or even its shadow, and
warns all birds of the coming danger with a loud whistle, which at
once sends them into hiding, while the Chopi goes bravely out to the
encounter; and the result is invariably a victorious song on his part,
beginning with the sound of his own name, and running through a variety
of whistled notes. He also sings well in captivity and when his mate is
incubating; and his voice is first heard welcoming the dawn from the
eaves and tiled roofs of houses where he roosts. The pairing-season is
in November; and, Noseda adds, the breeding-place is a hole in a bank,
or tree-trunks, or in a wall under the eaves, and occasionally the nest
is made in the small branches of an orange or other close-leafed tree,
and is built of sticks and straws carelessly disposed, with a few
feathers for lining. The eggs are four, and white.
It may be added that between Azara and his friend Noseda there was
a great controversy respecting the parasitical habits of the common
Cow-bird (_Molothrus_), which were first discovered by the former; and
disbelieved in by Noseda, who accounted for the fact that the Cow-bird
is never seen to make a nest by supposing that species to be the
year-old young of the Chopi, which, he further imagined, took three
years to acquire the adult form and plumage. Such an idea might seem to
discredit Noseda as a naturalist, if we did not remember that Gilbert
White at the same period was trying to prove the hybernation of Swallows
in England. The whole of the discussion appears in the 'Apuntamientos,'
under the description of the Chopi; and Noseda is there allowed to
state his own case; after which the better observer, Azara, gives five
objections to the theory, any one of which would be sufficient to
demolish it.
Fam. XII. CORVIDÆ, or CROWS.
The typical black Crows and Ravens do not penetrate into the New World
so far south as South America, their range terminating in the highlands
of Guatemala and the islands of the Greater Antilles. They have,
however, as representatives in South America several allied groups, clad
mostly in various shades of blue, and commonly known as Blue Crows and
Blue Jays. Two of these are known to occur in the woods of the northern
provinces of Argentina.