BIRDS OF THE REGION 159 



locality affords an excellent opportunity for a detailed 

 study of the habits of these remarkable birds. 



Rock wrens occur all through the cave region, and a 

 pair was evidently nesting in the wall of the big western 

 doorway of the cave. Their habit of building up a 

 little heap of stones at the entrance of a nest hole in the 

 rocks is quaint and unusual, and their bobbing, bowing, 

 and teetering antics and squeaky notes while they hop 

 about on the big rocks or cling with strong feet to the 

 cliffs and walls are especially noteworthy. 



Canyon wrens (Fig. 54), with their ringing songs 

 running down the scale, echoing from side to side of 

 the canyon walls, and issuing from the deep doorways 

 of almost every cave visited in this region, are among 

 the most thrilling and fascinating of the cave birds. 

 When I arrived on March 11, a pair was spending each 

 night down in the ladder shaft, but later as more 

 people were using the ladders they moved up to the 

 west entrance, where they were usually found within 

 the great doorway. Evidently they were considering 

 a nest site in a crack of the wall above the door. In a 

 small cave about three miles to the west a pair had a 

 nest in a hole in the limestone roof back in the first 

 twilight of the entrance, within easy reach of my hand. 

 The hole was so filled with sticks and fibers that I 

 could not see into the nest without injuring it, so I did 

 not make further examinations. But on April 19 

 the old bird was on the nest at mid-day and evidently 

 incubating. On April 29, a pair of these wrens was 

 busily feeding young in a little hole in the roof of the 

 big cave, high up on the east side of Slaughter Canyon, 



