Bulletin - United States National Museum - si-pddr - Smithsonian ...

BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 137
subsequent to that date. As Dr. L. Stejneger has pointed out in
a dissenting opinion accompanying this action of the International
Committee the names given in the edition for 1762 fulfill all of
the conditions imposed by the code to make them eligible.
STERNA TRUDEAUI Audubon
Sterna trudeaui Audubon, J. J., Birds of America (folio), vol. 4, 1S38,
no. 82, pi. 409, fig. 2. (Great Egg Harbor, N. J.)
Trudeau's tern was locally common in eastern and southern Buenos
Aires and near the coast in eastern Uruguay, but was not recorded
elsewhere. It was first noted on October 21, 1920, near Dolores in
eastern Buenos Aires, where I recorded a dozen or more in pairs
that flew back and forth along a drainage canal cut through a
marsh. As two passed near at hand I killed the female with a
shot from my collecting pistol. Near Lavalle the species was fairly
common from October 25 to November 15, and a second female was
secured on November 4. One shot October 31 was preserved as a
skeleton. Near Carrasco, east of Montevideo, Uruguay, one was
seen January 9, 1921, and on January 16 the birds were common.
The skull of a dead bird that had washed ashore was secured on
the latter date. One was observed on the coast at La Paloma below
Eocha, Uruguay, on January 23, and about 20 were recorded Janu-
ary 31 at the Laguna Castillos below San Vicente. One was secured
there in a helpless condition from alkali poisoning. Near
Guamini, Buenos Aires, from March 3 to 8 the species was fairly
common on the borders of the large lagoons. It was not unusual
to find 100 or more gathered in company with gulls. This point
was the farthest inland at which I noted the species, as elsewhere
it was foimd only along the coast or in level marshy areas near tide
water.
Trudeau's tern in flight and general actions is similar to other
smooth-headed terns. As the birds beat back and forth with zigzag
flight along shallow channels they darted down at intervals to secure
small fish that appeared in the water within striking distance.
When they were not feeding they gathered in close flocks to rest
on some sandy beach or point near water. Below Cape San Antonio
parasitic and long-tailed jaegers harried them and made them
disgorge. Once or twice I noted hooded gulls in similar attempts,
but in each case the tern with seeming ease eluded its less agile
pursuer.
The call notes of Trudeau's tern are sharp and explosive and
suggest in many ways the sounds emitted by Forster's tern, a species
that the present one suggests strongly in life. A usual call was a
sharp tik tik tik, changed when birds became angry or excited to
a drawn out keh-h-h. As birds in full plumage approach across