334 
ANAS SPINICAUDA 
to sixty yards. It is therefore evident that the typical wavj'^-line form assumed by all 
our northern ducks during migration is also common to this species. 
On the mountain plateaus large companies seem to be rare; groups or family 
parties up to eight are characteristic (Taczanowksi, 1886). 
Association with other Species. This Pintail is sociable, as well as gregarious. 
It will mingle rather freely with any or all ducks and Teal of the Argentine. Flocks 
composed equally of Pintail and Fulvous Tree Ducks, with a sprinkling of Rosy-bills, 
have been seen (E. Gibson, 1920). 
Voice. Like other Pintails this is an extremely quiet bird. Indeed, Captain 
Abbott (1861), writing of the Falkland Islands, says he never heard any note from 
them. Mr. Peters (MS.), who saw this species constantly through the breeding 
season in northwestern Patagonia, never heard the whistle characteristic of the male. 
I cannot say that I ever heard any sound from a captive pair which I kept. However, 
the call of the male resembles, and perhaps is exactly the same as that of the northern 
Pintail. Wetmore (MS.) describes it as a “mellow, trilled whistle, a purling sound 
pleasing to the ear,” and given frequently by parties of males on the wing. An ap- 
parently distinct note, probably used only in the breeding season, and presumably 
the same as the Teal-like proop heard from the Common Pintail on the breeding 
grounds, was noted by Peters (MS.), who describes it as a kriick. 
The female’s note is a low ka-ack or qua-ack slightly lower in tone than that of our 
Common Pintail (Wetmore, MS.). 
The trachea of the male is 180 mm. in length and uniform in size. The bulb is 
small, left-sided, roughly globular in shape, and measures 15 by 11 mm. The trachea 
of the female is simple, as in other ducks. 
Food. The Brown Pintail feeds almost anywhere, but it is particularly fond of 
rising waters which in flooding areas of muddy flats bring up windrows of seeds and 
dead or drowning insects. The seed of the giant thistle {Carduus mariana) which 
ripens on the pampa from January to April is spoken of by several writers as being 
a favorite food (P. L. Sclater and Hudson, 1889; C. H. B. Grant, 1911; E. Gibson, 
1920). They are often seen on open, dry land. Durnford (1877) found large flocks 
spending their time on the mussel-beds at the mouth of the Chubut. Their habit of 
feeding on ripe Indian corn when the cobs are collected in heaps has also been re- 
ferred to by various observers (P. L. Sclater and Hudson, 1889; E. Gibson, 1920). 
A series of seventeen stomachs collected by Mr. J. L. Peters at Huanuluan, Rio 
Negro Province, between August and January, and kindly analyzed by Mr. W. L. 
McAtee of the U.S. Biological Survey, gives a very good idea of the important 
duck foods of this particular region. The proportion of vegetable matter ranged from 
