18 " 2 ] SWALLOWS OF BUENOS AYRES. 845 



these cries are neither loud nor shrill. When flying, these Swallows 

 glide along very close to the earth, and when weary settle down (con- 

 trary to the custom of other Swallows) and rest 'on the level grassy 

 plains. Like other birds of this family they possess the habit 

 of gliding to and fro before a rider's horse to snatch up the little 

 twilight moths startled from the grass. Seldom does a person 

 ride on the pampas in summer without having a number of Swal- 

 lows gather round him ; often I have thought that more than a 

 hundred were before my horse at one time ; but, from the rapidity 

 of their motions, it is impossible to count them. I have also noticed 

 individuals of the four most common species of Swallow following me 

 together; but after sunset, and when the other species havelono- 

 forsaken the grass plains for the shelter of trees and houses, this dimf- 

 nutive Swallow continues to keep the traveller company. At such a 

 time, as they glide about in the dusk of evening conversing together 

 in low tremulous tones, they have a peculiarly sorrowful appearance 

 seeming like homeless little wanderers over the great level plains ' 

 \V hen the season of migration approaches, they begin to congre- 

 gate in parties not very large (though sometimes as many as one or 

 two hundred individuals are seen together) ; these companies spend 

 much of their time perched close together on weeds, low trees, fences 

 or other slightly elevated situations, and pay very little attention to 

 a person approaching, but seem preocupied or preved upon by some 

 anxiety that has no visible cause. 



_ This time immediately preceding the departure of the Swallows is 

 indeed a season of deep interest to the observer of nature. The birds 

 seem to forget their songs and aerial recreations ; the attachment of 

 the sexes, the remembrance of the spring is obliterated; they al- 

 ready begin to feel the premonitions of that marvellous instinct that 

 urges them hence : not yet an irresistible impulse, it is a vague sense 

 of disquiet; but its influence is manifest in their language and gest- 

 ures, their wild manner of flight, and listless intervals. The little 

 Atticora cyanoleuca disappears immediately after the other larger 

 species. Many stragglers continue to be seen after the departure & of 

 the main body; but before the middle of March not one remains the 

 migration of this species being very regular. 



I give a few more remarks on other species of Swallows, and I shall 

 have done with this family. I continue to meet so frequently with 

 single birds and small parties of the Rirundo leucorrhoa, even on the 

 coldest days of winter, that I am quite positive the birds of this 

 species breeding as far north as Buenos Ayres city migrate in an ex 

 ^eedingly irregular manner, many remaining with us all the year and 

 that the further south we go we find their migrations become more 

 strict and definite; for in Patagonia from March to August I saw not 

 one of them. The same may be said of some other migratory snecie* 

 in this region. J * 



This fall I noticed, as usual, large numbers of the Swallow of which 

 I spoke in my former remarks as closely resembling the H leucor 

 rhoa, but with chestnut tinges*. When they began to pass thev flew 

 * See P. Z.S. 1871, p. 328. 



