328 MR. W. H. HUDSON ON THE BIRDS OF BUENOS AYRES. [May 2, 



other, and tumble to the earth twenty times an hour, often struggling 

 on the ground for a considerable time, and heedless of the screams 

 of alarm their fellows set up above them ; for often while they lie 

 struggling do they fall an easy prey to some wily pussy, who thrives 

 on their disputes. When these troubles and feuds are finally ended, 

 they address themselves diligently to their great work, and build a 

 rather large nest. They are not neat or skilful workers, but merely 

 stuff a great quantity of straw and other light material into the hole 

 they build in, and line it thickly with feathers and horsehair. The 

 eggs are white and pointed, from five to seven in number. 



"All those species that are liable at any time to become the victims 

 of raptorial birds are much beholden to this Swallow, as he is the 

 most vigilant sentinel they possess : often when the Hawk is still far 

 off and the other birds unsuspicious of his approach, the Swallows 

 suddenly rush up towards the sky with a wild rapid flight, announcing 

 the evil tidings with distracted screams. These are well understood ; 

 and the alarm spreads like lightning through the feathered tribes, 

 which are all in terrified commotion, crouching in the grass and 

 plunging into thickets, or mounting upwards to escape by flight. I 

 have often wondered at this ; for surely this swift-winged little bird 

 is the least likely to fall a prey himself. 



" They have another habit which cannot but be grateful to the mind 

 of every lover of nature who is an early riser. An hour before 

 sunrise and ere any wild bird has broken the profound silence of 

 night, multitudes of these Swallows, as at the signal of a leader, 

 begin their song, at the same time mounting upwards into the still 

 dusky sky. Their notes at this time are different from the hurried 

 twitterings they utter through the day ; they are impressive, and, 

 though soft, may be heard at a long distance ; sounding far and 

 near, up in the sky, from so many throats, they have a most charming 

 effect that seems in peculiar harmony with the shadowy morning 

 twilight. 



" We often see a Swallow here bearing a general resemblance to the 

 H. leucorrhoa, but larger than that bird, without the blue and greeu 

 reflections or colouring, and with a tinge of chestnut on the neck, 

 rump, and sides. 



" It does not breed or remain any time with us ; but we see so much 

 of it that it should, I think, have its place in our ornithology. I 

 regret to say that I do not know its name or summer-home, not 

 possessing any of those large works on South-American species that 

 could probably enlighten me on the subject*. But even the neces- 

 sarily imperfect notice I can give of it will perhaps enable you to 

 determine its species. I have scattered through my papers numbers 

 of notes on this Swallow, having observed it much to discover the 

 direction of its flight ; but I have always found it very irregular in 

 its movements and times of appearing, also that it is vastly more 

 numerous some years than others. Indeed sometimes a season 

 passes without one individual being seen ; other years they have only 



* This species may possibly be Pefrochelidon americana (Gm.), ( = Hirundo 

 pi/rrhonota, Vieill.). — P. L. S. 



