376 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



calls of the swallows are even stronger; interjected at times were 

 some musical notes heard only occasionally at the time of the nuptial 

 period. 3.08 a. m. The notes given by the swallows are now becom- 

 ing less. At this time, the stars are faint. 3.11 a. m. The swallows 

 have ceased calling, having flown about for 45 minutes." 



In recording a similar experience on June 3, 1929, he writes : "The 

 twittering notes, given by the birds in the very early morning hours, 

 are somewhat like their ordinary ones, but there is this difference: 

 the notes are of a shrill, chattering character, more rapidly given, and 

 almost continuous, as if the bird was excited, though sometimes there 

 are very short pauses between the notes. The flight of the swallow 

 is also very erratic, more of a dashing or twisting kind, and each bird 

 seems to somewhat confine itself to a limited territory in the vicinity 

 of where it is nesting. From a long observation of the violet-green 

 swallow in the dim morning hours before sunrise, I incline to the 

 opinion that those in flight are the male birds, and their unusual 

 actions at this time can be attributed to the procreative impulse which 

 is at its height at this time, for the actions are at an end in the latter 

 part of June, when young swallows are in the nest." 



Nesting. — The violet-green swallow nests in holes, cavities, and 

 crevices in a variety of situations. In suitable localities, where the 

 birds are often very abundant, the demand is sometimes greater than 

 the supply, competition for the available cavities is keen, and the 

 birds cannot be too particular in the choice of a nesting site. Where 

 nesting cavities are numerous, the swallows often form colonies, with 

 many nests in a suitable tree or cliff. Charles F. Morrison (1888), 

 in Colorado, has "seen as many as twenty pair in a single dead pine, 

 and four or five pair in one limb which had been used first by the 

 woodpeckers." 



Throughout much of its range this swallow still continues to nest 

 in localities more or less remote from human habitations and under 

 primitive conditions, such as in deserted woodpecker holes and natural 

 cavities in trees, or cracks, crevices, or holes in various kinds of rocky 

 cliffs. Dawson and Bowles (1909) say that, in eastern Washington, 

 they still nest "to a large extent upon the granite or lava cliffs. In 

 the last-named situations they utilize the rocky clefts and inaccessible 

 crannies, and are especially fond of the smaller vapor holes which char- 

 acterize the basaltic formations. Favorable circumstances may at- 

 tract a considerable colony, to the number of a hundred pairs or more." 



In Arizona they nest mainly high up on the mountains in old 

 woodpecker holes in the pine belt, but a few pairs nest in the lime- 

 stone cliffs that form the walls of the upper canyons. In other places 

 they have been reported as using the old nests of cliff swallows and 



