VIOLET-GREEN SWALLOW 381 



Enemies. — The English sparrow is one of tlie worst enemies of this 

 and other swallows, as it preempts the nesting boxes or attempts to 

 oust the swallows from them. The sparrows begin nesting operations 

 earlier than the swallows and thus have the advantage, but, when once 

 well established, the swallows are not easily driven out. Bird lovers 

 that want to have swallows in their bird boxes must keep the sparrows 

 under control. 



Violet-green swallows are sensitive to w^eather conditions ; migrants 

 in early spring are often confronted by a sudden cold spell, which 

 forces them to retreat. At such times, when insects are scarce or 

 driven to cover, it is impossible for the swallows to obtain suflficient 

 nourishment and many of them perish and are picked up in an 

 emaciated condition. 



Mr. Rathbun tells me of one that was building a nest in one of 

 his boxes, using some horsehair in the lining; its wing became en- 

 i angled in one of the hairs, and it might have perished if it had not 

 been released by Mrs. Rathbun. 



Fall. — Mr. Rathbun (MS.) says: "After the young are on the 

 wing these birds disappear from the localities where they have nested 

 unless such happen to be in the vicinity of water, for the species seems 

 to be partial to such surroundings in the vicinity of streams or lakes 

 or even along tidewater. Here the birds will be seen hawking above 

 the low-lying fields or along the littoral line and, on occasions, perched 

 in numbers on the telegraph wires in the vicinity. These localities 

 appear to be the resorts of the violet-greens up to the time when they 

 take their departure in the autumn." 



Theed Pearse tells me that this is the first of the swallows to leave 

 the vicinity of Vancouver Island in summer, very few being left by 

 the end of July. Farther south they gather in large flocks during 

 August and depart from Colorado and New Mexico early in 

 September. 



Dr. Joseph Grinnell (1908) writes: "Many adults and full-grown 

 young were found congregated about the shore of Bear lake [San 

 Bernardino Mountains, Calif.] July 30 to August 2, 1905, On the bare 

 branches of one dead pine on the north shore of the lake, July 31, 

 hundreds (without exaggeration) of violet-green swallows were perch- 

 ing, mostly young-of-the-year. Individuals were constantly coming 

 and going, and occasionally nearly the entire flock would launch out 

 with loud twitterings, only to gather again within a few minutes. 

 It made me dizzy to watch the restless throng. A similar gathering, 

 though on a smaller scale, was witnessed near the South Fork of the 

 Santa Ana, July 24, 190C.'' 



Winter. — A few violet-green swallows spend the winter in the rel- 

 atively warm Imperial Valley in southern California, in the lower 

 Colorado Valley, and in northern Lower California. But the main 



