18/2.] SWALLOWS OF BUENOS AYRES. 609 



home ; this is a sort of declaration of war, and marks the beginning 

 of hostilities. The Oven-birds, full of alarm and anger, rush upon 

 and repel them as often as they approach ; they retire, but not dis- 

 comfited, and only warbling out their gay notes in answer to the 

 outrageous indignant screams of the Furnarii. Soon they return, the 

 scene is repeated, and this desultory skirmishing often continued for 

 many days. But at length the lawless invaders grown bolder, and 

 familiar with his strength and resources, will no longer fly from the 

 master of the house : desperate struggles now frequently "take place 

 at the entrance, the birds again and again dropping to the ground 

 clutched together, and again hurrying up only to resume the combat. 

 Victory at last declares itself for the aggressors ; and they busy them- 

 selves carrying in materials for the nest, screaming their jubilant 

 notes all the time, as if in token of triumph. Thus are the brave 

 and industrious Oven-birds often expelled from the house that cost 

 them so much labour to build. 



It is pleasant, however, to know that this is not the invariable 

 residt of the conflict. To the superior swiftness of the Swallow the 

 Oven-bird opposes greater strength, and, it might be added, a greater 

 degree of zeal and fury than can animate its adversary. The contest 

 is thus scarcely an equal one; and the Oven-bird, particularly when 

 its young are already hatched, is often able to maintain its own. But 

 the Swallows never suffer defeat ; for when unable to drive the Oven- 

 birds by force from their citadel, they fall back on their dribbling 

 system of warfare, and keep it up till theyoung birds leave it, 'when they 

 take possession before the nest has grown cold. 



The nest of this Swallow is composed chiefly of large feathers ; 

 the eggs are four, long, pointed and pure white. 



You will remark that, in all its habits I have mentioned, this bird 

 differs widely from the P. chalybea ; there is also great dissimilarity 

 in the manner of flight of the two birds. The P. chalybea moves 

 with surprising grace and celerity, the wings extended to their ut- 

 most ; they also love to sail in circles far up in the air, or about the 

 summits of tall trees, and particularly during a high wind. At such 

 times several individuals are usually seen together, and all seem 

 striving to outvie each other in the beauty of their evolutions. 



The P. tapera is never seen to soar about in circles ; and though 

 when hawking about for flies it sweeps the surface of the grass with 

 amazing swiftness, at other times it has a flight strangely slow, and 

 in a fashion peculiar to itself: the long wings are depressed as much 

 as those of a wild duck when dropping into the water, and constantly 

 agitated with flutterings short and rapid as those of a butterfly. 



Neither is the bird gregarious like all its congeners, though some- 

 times an individual associates for a while with a party of Swallows of 

 another species, but this only when they are resting on fences or 

 trees ; for as soon as they take flight he again leaves them. They hold 

 no meetings preparatory to migration, but skim about the fields and 

 open plains in un-swallow-like solitude, and suddenly disappear with- 

 out having warned us of their intended departure. 



Proc. Zool. Soc— 1872, No. XXXIX. 



