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

BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 59
male shot at the same locality on September 20 has the following
measurements: Wing, 358; tail, 127.5; exposed culmen, 106; tarsus,
112. Both of these birds are in full plumage and are similar save
that the female, in addition to being slightly smaller, is paler
throughout, and has the lower neck barred with black on the sides
and behind. A third bird, a female, shot 110 kilometers west of
Puerto Pinasco on September 23 is identified as the present species
with some reservation. It is juvenile, molting from juvenal plumage,
and may represent holivianuin instead of viai^iioraturri. In color it
is buff barred with black, as usual in young tiger bitterns, save that
the black bars are more restricted in width than in other specimens
examined. The crown and hind neck vary from mikado brown to
cinnamon, barred narrowly with black. New feathers that are appearing
on the upper back are dull black, barred narrowly with wavy,
irregular bars of cinnamon; others on the sides of the foreneck are
russet margined tipped and barred with black. This bird measures
as follows: Wing, 316; tail, 115.5; exposed culmen, 99; tarsus, 108
mm.
It is probable that Tigrisoma marmoratuTn will prove to be a sub-
species of T. Imeatum^ a species of northern range, from which it
differs mainly in larger size as far as may be judged from available
descriptions.
The tiger bittern is a species that frequents open shores of marshy
lagoons, often among growths of cattails or other rushes. Two
ranged about a lagoon at the Riacho Pilaga in Formosa during
August, 1920, but were wild and wary. On one occasion I knocked
one over with a broken wing and waded for it in Avater reaching to
my armpits, but was so impeded by mud and aquatic growth that the
heron swam to a mass of floating vegetation and was lost before I
reached it. Near Kilometer 80, west of Puerto Pinasco, Paraguay,
three were observed in Laguna Palmas, where they walked about on
floating plants that choked the Avater. When they flushed, one
alighted on a shaded perch in a tree, where I stalked it and shot it.
This bird, an adult female, had the bill black, with the lower half of
the mandible pale olive-buff, a color that extended along the gonys
to ih& tip ; bare skin from above eye to base of bill, wax yellow ; a line
from anterior canthus of eye to bill, and another above commissure
to below eye, deep neutral gray ; rest of bare skin on side of head and
over ramus of lower jaw, citron yellow; iris antimony yellow; front
of tarsus, and toes shading from chaetura black to chaetura drab;
back of
green.
tarsus for upper half varying from tea green to vetiver
The flight of these herons is slow and direct, accomplished with
slowly flapping wings, and in the air they appear as large as a great