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

286 BULLETIN 133, UNITED STATES NATIONAL MUSEUM
jerking their tails continually. They have several soft mewing or
nasal notes, but do not become as excited at intrusion as do many
small birds. A male taken February 7 (preserved as a skeleton)
was in breeding condition and from the appearance of the abdomen
had been engaged in incubation.
THAMNOPHILUS GILVIGASTER DINELLII Berlepsch
Thamnophilus dinellii Berlepsch, Bull. Brit. Orn. Club, vol. 16, May 28,
1906, p. 99. (Estancia Isca Yacu, Santiago del Estero, Argentina.)^''
The bird here treated has been known variously as maculatios,
caerulescens, and gilvigaster until dinellii was described by Berlepsch.
The present combination seems to have been made first by Hartert.^''
Of this form I collected the following skins : Resistencia, Chaco,
July 9, 1920, male and female; Las Palmas, Chaco, July 13, 14, 20,
21, and 30, two males and three females; Riacho Pilaga, Formosa,
August 8 and 11, two females; Tapia, Tucuman, April 12, 1921,
immature female. These differ from gilvigaster from Uruguay in
uniformly paler coloration on the ventral surface, Avith the grayish
wash of the breast lighter and less extensive. Birds from the Chaco
agree in general with the single skin from Tapia, Tucuman, though
this bird from Tucuman, and two from the Eiacho Pilaga. Formosa,
are slightly grayer on the dorsal surface than the series from the
Territory of Chaco.
The present ant bird, in the Chaco, was common in dense undergrowth
under heavy trees, but at times was found in more open
groves scattered over the savannas. In general it had the motions
of a titmouse, save that it did not cling to limbs, but with this
mannerism combined the jerking of the tail and twitching of the
wings of a flycatcher. It fed at times on the ground, where it hopped
slowly about, pausing to peer around, but more often worked through
limbs rising 3 or 4 meters from the ground. The birds had much
curiosity and were easily called out from the heavier coverts. Their
notes were somewhat varied, the usual one resembling pruh yruh
pruh-h, given in a mewing tone. In spring, males mounted into the
top of some bush or low tree where, concealed in the leaves, they
sang a pleasing whistled repetition of notes suggestive of the song
of the white-breasted nuthatch {Sitta carolinensis)
The Toba Indians called them Jcwo o likh.
A male, shot July 9, had the maxilla and extreme tip of the
mandible black; base of mandible gray number 5, with an indis-
tinct, grayish line along the cutting edge ; tarsus and toes slate gray,
underside of toes yellowish ; iris dark brown. A female was similar
but had the colors somewhat duller.
58 Hellmayr, Field Mus. Nat. Hist., Zool. ser., vol. 13, pt. 3, Nov. 20, 1924. p. 103,
states ttiat Berlepsch's type specimen comes from Santiago del Estero, though In the
original description it is listed from Tucuman.
«' Nov. Zool.. vol. 16, 1909, p. 221.
.