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

340 BUI^LETIN 133, UNITED STATES NATIONAL MUSEUM
light eye was prominent at a considerable distance. The birds passed
from perch to perch, with an undulating flight not far above the
ground, and as they checked their momentum in order to alight
spread the tail, displaying its prominent white markings. At times
they hopped down among the branches to conceal themselves among
dense leaves.
In the vicinity of Victorica, Pampa, from December 23 to 29,
Phytotonia 7^tila was encountered in abundance on its breeding
grounds, and six preserved as skins include three adult males, an
adult and an immature female, and a fledgling. At this season the
species ranged in wooded areas of low, heavy-trunked calden, algarroba,
and similar trees where there was abundant dense undergrowth
of chaiiar, piquillin, and a variety of fow shrubs, many with thornprotected
branches. On entering these tracts for the first time my
attention was drawn at once by one of the most bizarre bird notes
that has as yet come to my ears, and, hastening to trace it, I found
to my astonishment that it was the song of this plant cutter. Adult
males in full, handsome plumage rested on open limbs, often at the
tops of low trees, and with great earnestness gave a succession of
low notes that may be likened only to the drawn-out squeaking produced
when two tree limbs, moved by winds, rub slowly across one
another. Occasionally a more strenuous effort produced a sound
like the squeaking of leather, that might terminate in a froglike
croak. The whole, while ranking as a musical performance of the
highest rank in the opinion of the one responsible for it, and without
doubt the sweetest of music to his mate, was to human understanding
ridiculous to an extreme. At intervals they flew from perch to perch
with slow affected flight, performed with rapid beats of the wings,
different entirely from their usual method of progression.
It is possible that two broods are raised, as one fledgling and one
fully grown immature bird were taken, while adult males were in
full breeding condition. The fledgling, though as yet unable to fly,
retreated precipitately among the thorny limbs of a i:)iquillin, where
it was secured only with difficulty. The birds were feeding on green
drupes of various sorts, and all those taken, here and elsewhere, had
the sides of the bill covered with gum from plant juices.
At Potrerillos, Mendoza, an immature female was shot March 19,
1921, at an elevation of 1,800 meters.
In the specimens from the areas listed, there are no differences
apparent other than those that may be considered individual. The
fledgling taken, a young male, suggests the female in color pattern,
save that the coloration is softer and darker, and the streaks on
both dorsal and ventral surfaces more obscure. The under tail
coverts are tawny olive, with obscure shaft streaks of black. Immature
females in full juvenal plumage have the streaking nar-