COMMON SWALLOW 35 



August I did not meet with a single individual* In 

 Buenos Ayres the autumnal migration of the Hirun- 

 dines begins about the middle of February, and from 

 that date vast numbers of this Swallow are seen 

 travelling north, and, in some seasons, they continue 

 passing for over a month. One autumn, in April, 

 several days after the Swallows had all disappeared, 

 flocks of the Common Swallow began again to appear 

 flying north, and for ten days afterwards they con- 

 tinued to pass in large numbers* They would stoop 

 to dip themselves in a pool where I observed them, 

 and then alight on the reeds and bushes to rest, and 

 appeared quite tired with their journey, rising reluc- 

 tantly when approached and some allowing me to 

 stand almost within arm's length of them without 

 stirring. I had never before observed any later or 

 supplementary migration like this ; for as a rule the 

 causes which in some years delay the departure of 

 birds seem to affect them all alike. Possibly these 

 late birds come from some remote district, where 

 exceptionally cold weather had retarded breeding 

 operations. 



The Common Swallow sometimes lays in a tree, 

 in the large nest, previously abandoned, of the 

 Lenatero (Anumbius acuticaudatus). Its favourite site 

 is, however, a hole in a wall, sheltered by the over- 

 hanging tiles or thatch ; for though it does not go 

 much into towns, as Azara has remarked, it is very 

 domestic, and there is not a house on the pampas, 

 however humble it be, but some of these birds are 

 about it, sportively skimming above the roof, or 



