BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 77 



small flocks, at times as many as 50 together, near the mouths of 

 fresh-water arroyos draining into the strongly saline Lago Epiquen, 

 or in small ponds common here in slight depressions through the 

 undulating pampa. The birds rose with a high-pitched call, and on 

 the wing in flight and form resembled Daflla spinicauda, a species 

 from which they were easily distinguished by the buffy-brown tail 

 (in color distinctly lighter than the back) and by the sharply defined 

 lines of their bicolored heads. 



As no specimens were taken these notes are allocated under the 

 subspecies ruhrirostris on the basis of Bangs's recent review of the 

 group.^^ 



NETTION FLAVIROSTRE (Vieillot) 



Anas flavirostris Vieillot, Nouv. Diet. Hist. Nat., vol. 5, 1816, p. 107. 

 (Buenos Aires.) 



The curious nesting habits of the tree or yellow-billed teal have 

 been well described by the late Ernest Gibson in his notes on birds of 

 the Cape San Antonio region, Province of Buenos Aires.^^ While 

 working at Mr, Gibson's estancia, Los Yngleses, near Lavalle, from 

 October 30 to November 9, 1920, I found the birds fairly common. 

 The breeding season had begun and the teal were nesting in huge 

 stick nests of the monk parrakeet {Myioj)sitta monachus) placed in 

 the tall eucalyptus trees lining the driveways near the estancia house. 

 The birds themselves spent much of their time resting 40 or 50 feet 

 from the ground on open horizontal limbs in the eucalyptus, where 

 they stood on one leg asleep with the bill in the feathers of the back 

 as calmly as though they rested on some mud bar in a lagoon. 

 Though six or eight frequently congregated in these situations, 

 when flushed the birds separated in pairs that circled swiftly over 

 the open fields to return to some safer haven among the trees. The 

 males gave a low whistle and the females a high-pitched kack hack 

 ka-ack^ notes that in both cases resembled those of the similar sex 

 in the green-winged teal {Nettion carolinense) . In fact, the re- 

 semblance to the call of the northern bird was so close that I never 

 overcame a feeling of surprise when I heard the present species call 

 from the treetops. 



After heavy rains the tree teal descended to shallow pools in the 

 grassy fields near at hand, but at other times flew out to feed in the 

 marshes and swamps in company with other ducks. Males taken 

 were in full breeding condition. On October 31 I observed a male 

 on the wing in pursuit of a female, giving his musical whistled note. 

 The two circled and swimg swiftly through the tops of the trees in a 



^■^ Proc. New England Zool. Club, vol. 6, Oct. 31, 1918, p. 89. 

 "Ibis, 1919, pp. 20-21. 



