May, 1918 



THE WHITE-THROATED SWIFT IN COLORADO 



107 



could not be reached from this bench, nor was there any secure footing on 

 which the ladder, after being drawn to the third lift, could be placed so as to 

 reach the diagonal crevice to be explored. However, after securing the best 

 rest possible for the upper end, the lower extremity was supported by two men 

 on the insecure footing available, while the third man carefully climbed to the 

 crack in the rock. From this point, and without any disaster, he secured nest 

 number two, with four nearly fresh eggs, placed about two feet back in the 

 crevice. (See fig. 16.) 



While watching and admiring the powerful, graceful, and apparently ef- 

 fortless flight of these unrivalled masters of the air, I noticed what appeared 

 to be a conflict in midair, in which two birds clinched, fluttered, and fell as if 

 with broken wing, ten or twenty feet before separating. I had heard of their 

 copulating in flight, but was still somewhat skeptical. Neidrach assured me, 

 however, that he had frequently noticed 

 this while in company with Mr. F. C. Lin- 

 coln, Curator of Ornithology, Colorado 

 Museum of Natural History, who had 

 taken them in the act. Mr. Lincoln veri- 

 fies this statement and adds that in May, 

 1915, while on a collecting trip in the 

 Paradox Valley, Colorado, he frequently 

 observed this curious action. On two oc- 

 casions he collected with a single shot the 

 two birds while in the act, and both times 

 one proved to be a male, the other a fe- 

 male. Examination of the sexual organs 

 showed them to be in full breeding condi- 

 tion. The difference of about a month be- 

 tween the date of his observations and my 

 own is accounted for by the difference in 

 seasons, altitude and latitude. 



The balance of the four days we 

 spent at these cliffs was much a repeti- 

 tion of the foregoing, the nest sites dis- 

 covered being protected by overhanging 

 projections and mostly on the sides of 

 inaccessible pinnacles. In one instance 



one was located on the face of the main bluff back of some steeples, perhaps 

 one hundred feet below the mesa above, and thirty feet above the top of a chim- 

 ney slide, to which one of the boys laboriously climbed. We anchored and low- 

 ered the swing outfit with a view of raising him to the nest, but the swing in 

 passing the projections, and the manipulation of the rope afterwards, contin- 

 ued displacing such volumes of loose materials that it would have been suicidal 

 to have attempted reaching the nest. A Raven's nest and also a Red-tailed 

 Hawk's nest, similarly located at different points on the main cliff, were aban- 

 doned for the same reason. 



This year (1917), with three assistants, I revisited this same site by auto- 

 mobile, when a day and a half of hard and conscientious work was but a repe- 

 tition of the foregoing experience, except that no nests located could be 

 reached from below or above, and none was taken. On my return to Denver, 1 



Fig. 17. Fifty feet from the bot- 

 tom, BUT UNABLE TO REACH NEST 

 SITE BENEATH PROJECTING ROCK. 



