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

BIKDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 313
ENTOTRICCUS STRIATICEPS (d'Orbigny and Lafresnaye)
Muscisaxicola striaticeps d'ORBiGNrr and Lafbesnaye, Mag. Zool., 1837,
cl. 2, p. 66. (Chiquitos, Bolivia.)
Dr. Hellmayr ^° has determined that this species, known for many
years as einer^eus Sclater,^^ should bear the name of striaticeps as in-
dicated above. He writes that the type, in the Paris Museum, is
labeled as taken at Chiquitos, Bolivia, though in the original description
the species is said to come from La Paz. The greatly narrowed
l)rimaries in this species distinguish it not only from Knipolegus,
but also from all other flycatchers. Mr. Ridgway described the pequ-
liarities of this bird when he erected the genus Phaeotriccus, but as
through inadvertence he designated Gnipolegus hudsoni as type, the
name PTiaeotnccus must be used for hudsoni. As striaticeps is undoubtedly
peculiar, the present writer and Peters"^ have proposed
that it be called Entotriccus. It is characterized by greatly narrowed
primaries with the sixth to the tenth (outermost) distinctly
falcate; seventh primary longest; tenth shorter than the first.
This flycatcher was recorded at the following points: Riacho
Pilaga, Formosa, August 8 (adult female taken), 13 (two females
and a male) and 18; Puerto Pinasco, Paraguay, September 3; Kilometer
80, west of Puerto Pinasco, September 9, 10 (a female shot)
and 15 ; Tapia, Tucuman, April 7 to 13, 1921 (two males and a female
taken April T and 9). The female taken at Tapia is less heavily
streaked on throat and breast than skins from the Chaco, so that it
is paler below, a difference due in part perhaps to the fact that the
specimen is in fresh fall plumage. Females are identical with
males in wing formula and in the narrowed form of the primaries.
In the Chaco, during the winter season, these alert little flycatchers
sought low perches on the sheltered sides of dense groves of forest,
where they were protected from cold winds. In the warmer, more
open scrub near Tapia, Tucuman, they were scattered at random
through little valleys, though more frequent perhaps along deep-
cut barrancas that were common in this region. When at rest the
tail twitched constantly, heightening their superficial resemblance
to smaU Empidonax. During warm forenoons, in pleasant weather,
males, from a perch at the top of a low tree or a dead limb, frequently
shot straight up for a distance of 20 feet, turned and descended head
first, with closed wings until just above the former perch, when the
velocity of their fall was checked with a sudden rattle of wings, and
the bird once more was at rest, as nonchalant and jaunty as though
s«Nov. Zool., Julj', 1906, pp. 318-319.
"^ Cnipolef/us cinereus Sclater, Proc. Zool. Soc. London, 1870, p. 58. (Corumba,
Matto Grosso.)
"» Proc. Biol. Soc. Washington, vol. 36, May 1, 1923, p. 144. Type, by original designation,
MuaciaaMcola striaticeps d'Orbigny and Lafresnaye.