Mav.1918 



THE WHITE-THROATED SWIFT IN COLORADO 



105 



The cliffs where the birds were seen, bordering the Grand River, east of 

 Sulphur Springs, are of a mixed lava formation, with some parts of hard, ring- 

 ing material, and others of cracked, crumbling formation, intermixed with 

 seams and deposits of soft lava ash, through which the river has cut its way in 

 ages past. The visible base of the cliffs is at the top of a steep slope of debris, 

 extending to the Grand River several hundred feet below (see fig. 13). The 

 mesa above the cliffs is open rolling country covered with sage brush and na- 

 tive grass. 



The day following our arrival we felt our way carefully around the base of 

 the bluffs, at times starting displace- 

 ments of rock that rolled, bounded and 

 smashed their way to the foot of the 

 slope below us. In the air there was 

 an abundance of Cliff Swallows, inter- 

 mixed with a number of Violet-greens 

 and an occasional Swift ; and we were, 

 of course, constantly watching the last 

 mentioned, alert to locate their entrance 

 to and departure from crevices indi- 

 cating nest sites. Several of these en- 

 trances were spotted which were inac- 

 cessible from above, owing not only to 

 the extremely rotten and treacherous 

 character of the surrounding material, 

 but also to the fact that they were plac- 

 ed in steeples or pinnacles, separated 

 from the main bluff. Crevices selected 

 for nesting sites on the sides of these 

 steeples were generally overhung by 

 projecting rock. (See fig. 14.) 



The first available prospect, located 

 by Niedrach through the presence of 

 excrement about eight feet up, and to 

 which he was able to climb, was in a 

 horizontal crevice about two and one- 

 half inches in width, sloping slightly 

 downward and partly filled, in places, 

 with lava, sand and vegetable matter 

 evidently deposited by the wind (see 

 fig. 15). Upon reaching the crevice a 

 Swift darted forth nearly in his face, 

 and he caught site of its mate retreatin'g 



back into the crevice, from which it was not seen to emerge. Less than an 

 hour's work resulted in collecting, from a point about eighteen inches back, our 

 first nest, containing four fresh eggs. 



This seemed so "dead easy" that we were greatly encouraged, and we soon 

 spotted a second prospect in a nearly vertical crevice about ten feet up in a V- 

 shaped chimney. This was overhung with such suspiciously loose looking ma- 

 terial that we brought a couple of long cotton-wood fence rails from the river 

 bank below and pried loose several hundred pounds of rock, large chunks of 



Fig. 15. Nesting crevice of White- 

 throated Swift, showing method 

 of gaining access. 



