(BLACK-TAILED SKIMMER.)
+Rhynchops nigra+, _Burm. La-Plata Reise_, ii. p. 520 (Rio Paraná);
_Scl. et Salv. P. Z. S._ 1869, p. 634 (Buenos Ayres); _iid.
Nomencl._ p. 147; _Durnford, Ibis_, 1877, p. 209 (Buenos Ayres);
_White, P. Z. S._ 1882, p. 628 (Buenos Ayres). +Rhynchops
melanura+, _Saunders, P. Z. S._ 1882, p. 522.
_Description._--Above brownish black; forehead and wing-band white;
tail black: beneath white; bill, apical half black, basal half
orange; feet red: whole length 19·0 inches, wing 15·0, tail 5·0.
_Female_ similar.
_Hab._ Coasts of South America.
The Black-tailed Skimmer, which is common on the coasts of Brazil,
migrates south in spring, following the course of the Plata river in its
journey, and appearing in pairs or small flocks in the neighbourhood of
Buenos Ayres during the month of October. Its chief breeding-ground is
on the extensive mud-banks and islets at Bahia Blanca on the Atlantic
coast. The return-migration occurs in March.
Darwin met with the Scissor-bill during his excursion up the Paraná in
October 1833, and speaks of it as follows (Nat. Journ. p. 161):--
"I here saw a very extraordinary bird, called the Scissor-beak
(_Rhynchops nigra_). It has short legs, web feet, extremely long-pointed
wings, and is of about the size of a Tern. The beak is flattened
laterally, that is in a plane at right angles to that of a Spoonbill or
Duck. It is as flat and elastic as an ivory paper-cutter, and the lower
mandible, differently from every other bird, is an inch and a half
longer than the upper. I will here detail all I know of the habits of
the Scissor-beak. It is found both on the east and west coasts, between
lat. 30° and 45°, and frequents either salt or fresh water. The specimen
now at the Zoological Society was shot at a lake near Maldonado, from
which the water had been nearly drained, and which, in consequence,
swarmed with small fry. I there saw several of these birds, generally in
small flocks, flying backwards and forwards, close to the surface of the
lake. They kept their bills wide open, and with the lower mandible half
buried in the water. Thus skimming the surface, they ploughed it in
their course; the water was quite smooth, and it formed a most curious
spectacle to behold a flock, each bird leaving its narrow wake on the
mirror-like surface. In their flight, they frequently twist about with
extreme rapidity, and so dexterously manage, that with their projecting
lower mandible they plough up small fish, which are secured by the upper
half of their scissor-like bill. This fact I repeatedly saw, as, like
Swallows, they continued to fly backwards and forwards, close before me.
Occasionally, when leaving the surface of the water their flight was
wild, irregular, and rapid; they then also uttered loud, harsh cries.
When these birds are fishing, the length of the primary feathers of the
wings is seen to be quite necessary, in order to keep the latter dry.
When thus employed, their forms resemble the symbol by which many
artists represent marine birds. The tail is much used in steering their
irregular course.
"These birds are common far inland along the course of the Rio Paraná;
it is said they remain during the whole year, and breed in the marshes.
During the day they rest in flocks on the grassy plains, at some
distance from the water. Being at anchor, as I have said, in one of the
deep creeks between the islands of the Paraná, as the evening drew to a
close, one of these Scissor-beaks suddenly appeared. The water was quite
still, and many little fish were rising. The bird continued for a long
time to skim the surface, flying in its wild and irregular manner up and
down the narrow canal, now dark with the growing night and the shadows
of the overhanging trees. At Monte Video I observed that some large
flocks during the day remained on the mud-banks at the head of the
harbour, in the same manner as on the grassy plains near the Paraná; and
every evening they took flight direct to seaward. From these facts, I
suspect that the _Rhynchops_ generally fishes by night, at which time
many of the lower animals come most abundantly to the surface. M. Lesson
states that he has seen these birds open the shells of the _Mactræ_,
buried in the sand-banks on the coast of Chile; from their weak bills,
with the lower mandible so much produced, their short legs and long
wings, it is very improbable that this can be a general habit."