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 (Yieill.) ; 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 ten feet from the 
ground. At a distance they are not easy to distinguish from 
Hirundo leucorrhoa; 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. 
