AVES HIRUNDINID^. 817 



Description. — Adult female, 283961 Biol. Survey Colin. U. S. Dept. 

 Agriculture, General Roca, Rio Negro, Argentina, November 27, 1920, 

 Alexander Wetmore. Total length, 5. 10 inches ; wing, 4.08 ; culmen, .23; 

 tail, 2.10; tarsus, .56. Above glossy metallic blue, wings and tail dull 

 brownish black, below white ; largest under tail coverts blackish with me- 

 tallic blue tips. 



Sexes alike. 



Geographical Range. — Argentina to central Patagonia (Chupat Valley). 



Mr. Peters found them at Huanuluan when they arrived October 9 and 

 frequented "sandy flats along the line of cart-paths, where old ruts and 

 horse-tracks formed miniature banks where they make their burrows." 

 (Bull. M. C. Z. Ixv. No. 9, p. 327.) 



This species, the Golondriuas timoneles negros of Azara, is the smallest 

 of the Patagonian swallows. W. H. Hudson says: "In Buenos Ayres 

 these swallows appear early in September. They are bank-birds, breeding 

 in forsaken holes and burrows (for they never bore into the earth them- 

 selves), and are consequently not much seen about the habitations of man. 

 They sometimes find their breeding holes in the banks of streams, or in 

 peopled districts in the sides of ditches, and down in wells. But if in 

 such sites alone fit receptacles for their eggs were found, the species, in- 

 stead of one of the commonest, would be rare indeed ; for on the level 

 pampas most of the watercourses have marshy borders, or at the most 

 but low and gently sloping banks. But the burrowing habits of two other 

 animals, the Vizcacha {Lagostomus trichodactyhts) and the bird {Geositta 

 cmiicularia) have everywhere afforded the Swallows abundance of 

 breeding-places on the plains, even where there are no streams or any 

 other irregularities in the smooth surface of the earth. 



"The Geositta bores its hole in the sidesof the Vizcacha's burrows ; and 

 in this burrow within a burrow the Swallow lays its eggs and rears its 

 young, and is the guest of the Vizcacha and as much dependent on him as 

 the Wren or the Swallow we call domestic is on man ; so that in spring 

 when this species returns it is in the villages of the Vizcacha we see them. 

 There they live and spend the day, sporting about the burrows, just as the 

 domestic Swallow does about our houses. The nest, constructed of dry 

 grass lined with feathers, is placed at the extreme end of the burrow, and 

 contains five or six white, pointed eggs. After the young have flown, they 

 sit close together on a weed, thistle-top, or low tree, and the parents con- 



