the Province of Buenos Ayres. 169 



ing its wings over its back in the midst of its aerial evolutions, 

 and then dropping some distance through the air before taking 

 flight again. In the summer these birds congregate in large 

 parties, and seem never tired of circling about the topmost 

 branches of some wide-spreading ombo-tree, which is their 

 favourite resort. 



11. Petrochelidon pyrrhonota (Vieill.) ; Scl. et Salv. 

 Nomencl. p. 14. 



The only occasion on which I have seen this bird was on 

 the 25th of March of the present year, when I observed about 

 half a dozen at different times during the day, all flying 

 steadily in a north-easterly direction. This was about thirty 

 miles to the west of Buenos Ayres. From their manner of 

 flight, always keeping in the same general course, though 

 occasionally turning aside to chase some insect, I have no 

 doubt they were migrating : they kept about teu feet from the 

 ground. At a distance they are not easy to distinguish from 

 Hirundo leucorrlioa ; but on a nearer approach their greater 

 size and chocolate throat, but more especially their reddish- 

 brown rumps, are clearly discernible. The museum pos- 

 sesses one specimen, killed in this neighbourhood. 



12. Hirundo leucorrhoa, Vieill. ; Scl. et Salv. P. Z. S. 

 1868, p. 139. 



Arrives early (I saw some on the 10th August last year), 

 and does not leave us till the middle of April. I speak of 

 the main body ; for many birds remain with us all the winter. 

 On the 30th July I saw two or three hundred of them in the 

 course of a long walk a little to the north of Buenos Ayres. 

 It was quite warm and very fine, not at all like winter. 



This is the most common species of Swallow we have, and 

 there is scarcely a rancho in the country that has not its one 

 or two pairs breeding under the eaves or in the cracks of the 

 walls. It also resorts to holes in trees for nesting-purposes. 

 Though during cold and dull weather in the winter none are 

 visible sometimes for weeks together, a warm bright day 

 never fails to attract some from their temporary shelter, wher- 

 ever that may be. Pretty common at'Baradero in April. 



