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232 BULLETIN 133, UNITED STATES NATIONAL MUSEUM
hill slopes above were little nooks protected from wind and warmed
by radiation from the sun-heated stones, to which the hummers re-
sorted to rest, and from which they darted down at intervals to feed
on the flower clumps below.
Near Tapia, Tucuman, from April 7 to 13, this species, found as
before about the brilliant flower clusters of Psittacanthus, was common.
The birds were especially active on days of bright sunshine.
Males and females alike poised with vibrating wings in feeding, and
at frequent intervals paused to rest on open twigs, usually in the
sun as the weather was cool. When three or four gathered at one
flower clump there was much fighting among the long-tailed males,
while any intruder was greeted with a low chattering call, chit-it,
that often came from birds prudently concealed behind the dense
shelter of thorny branches. When on the wing both sexes frequently
expanded the deeply forked tail, a display, of course, most prominent
in the long-tailed males, and males at rest often jerked the tail up
and down in gnat-catcher fashion. The flight was rapid and direct,
though the bird had the usual hummer habit of swinging up or down
with an irregular bounding motion. Because of the long tail it appeared
large and was easier to folloAv with the eye than most hummers.
A few were seen near 2,100 meters on the Sierra San Xavier
above Tafi Viejo, Tucuman, on April 17.
A male, taken March 19 above Potrerillos, was molting on the
tkroat and had the tail almost grown anew. A male (April 9) and
four females (April 8, 9, and 13) from Tapia were in partial molt
on head, tail, and body. Immature females differed from the single
adult taken in larger green spots on the throat and a wash of cinnamon
on this area. In an adult male when freshly taken the bill
and tarsus were black; iris liver brown.
HELIOMASTER FURCIFER (Shaw)
Trochilus Furcifer Shaw, Gen. Zool., vol. 8, pt. I, p. 280. (Paraguay.)
A female taken near Las Palmas, Chaco, on July 31, 1920,
like other hummers seen here (in winter) was found near the border
of forest, in a region protected from cold winds. The bird, attracted
by squeaking, alighted with a subdued humming of its wings on a
limb near at hand.
The bill, tarsus, and toes, in life, were black.
Family MICROPODIDAE
MICRCPUS ANDECOLUS DINELLII (Hartert)
Apus andecolus dinellii Hartert, Bull. Brit. Orn. Club, vol. 23, December
31, 1908, p. 43. (Angosta Percliela, altitude 2,550 meters, Jujuy,
Argentina.
Dinelli's swift was recorded first in the valley of the Rio Negro
soutli of General Roca, Rio Negro, on November 27, 1920, when 10