BIEDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 21 



position was that birds on the latter course had come south by the 

 interior route perhaps to reach the coast near Bahia Blanca, and 

 were now turning to seek their winter homes. 



With regard to the migratory movement of native birds, particu- 

 larly in Argentina, many instances are noted in the writings of Dab- 

 bene, Gibson, Hudson, and others, while Peters has given an account 

 of the arrival of a number of species in northern Patagonia. In 

 general, such migratory movements are as readily evident to the 

 field observer as in northern regions. Large numbers of ducks of 

 various kinds, seed snipe, small ground-haunting flycatchers {Les- 

 sonia r. rufa), a subspecies of house wren, and other birds appear in 

 the Province of Buenos Aires from more southern regions at the 

 commencement of winter, and wholly or in part withdraw again as 

 summer approaches. Other species, as Thermochalcis Jongirostris. 

 are regular birds of passage from Brazil to Patagonia. The migra- 

 tory flights of the fork-tailed flycatcher are as evident as those of the 

 northern kingbird {Tyrannus tyrannus), for at the end of January 

 these birds gather in flocks and begin a northward movement that 

 carries all to Brazil during the following month. The jacana, the 

 sulphur-bellied flycatcher {Myiodynastes solitarius)^ two species 

 of martins {Progns elegans and Phaeoprogrie t. tapera), and a small 

 swallow {Iridoprocne alhiventris) are summer visitants near Buenos 

 Aires that retire at the approach of cold, as do the greater part of 

 other small species, some of whose individuals are hardy enough 

 to remain. 



Even in the Paraguayan Chaco, in the edge of the Tropics, the 

 spring migration was easily evident, as with the approach of warmer 

 days in September Podager nacunda passed in small numbers to 

 the south (making as regular a flight as the North American night- 

 hawk), a kingbird {Tyrannus tn. melancholicus) ^ and another fly- 

 catcher {Myiodynastes solitarius) appeared, and a little goatsucker 

 {Setopagis parvulits), hitherto absent, began its tremulous calls 

 at evening. 



The low woodland of the level reaches of the Chaco, with its 

 dense jungle impervious to cold winds, and its tangled openings, 

 where the sun may be warm even on sharp frosty mornings, harbors 

 many winter visitants from the more open country to the south, or 

 from the mountain slopes to the west. Here many small flycatchers, 

 warblers, and other insect-eating birds rest in comfort and security, 

 remaining quiet during brief spells of cold and becoming active when 

 the sun appears. The woodlands to the westward that cover the 

 low hills in northern Tucuman are also attractive at this season, and 

 at times small birds are so abundant there that they fairly swarm. 



Altitudinal migrations were easily evident in the Andean foot- 

 hills in Mendoza, as flycatchers and others came working down 



