Let us return to the first rock wren I saw. He was exceedingly shy, scurrying off to a more distant perch--another stone--as I approached. Sometimes he would run down among the bushes and rocks like a mouse, then glide to the top of another stone, and fling his pert little aria at the intruder. It was interesting to note that he most frequently selected for a singing perch the top of a high, pointed rock where he could command a view of his surroundings and pipe a note of warning to his mate at the approach of a supposed enemy. Almost every conspicuous rock on the acclivity bore evidence of having been used as a lookout by the little sentinel. This wren is well named, for his home is among the rocks, in the crannies and niches of which his mate hides her nest so effectually that you must look long for it, and even after the most painstaking search you may not be able to find it. The little husband helps to lead you astray. He will leap upon a rock and send forth his bell-like peal, as if he were saying, "Right here, right here, here is our nest!" but when you go to the spot, he flits off to another rock and sounds the same challenge. And so you can form no idea of the nest site. My nearest approach to finding a nest was among the rocks and cliffs on the summit of a mountain a few miles from Golden, where an adult bird was seen to feed a youngster that had already flown from the nursery. It was interesting to know that the rock wrens breed at so high an altitude. However, they are not an alpine species, none having been seen by the writer over eight thousand feet above sea-level, although they have been known to ascend to an altitude of twelve thousand feet. The fourth member of our feathered quartette was the oddest of all. On the thirtieth of June my companion and I were riding slowly down the mountain side a few miles below Gray's Peak, which we had scaled two days before. My ear was struck by a flicker's call above us, so I dismounted from my burro, and began to clamber up the hillside. Presently I heard a song that seemed one moment to be near at hand, the next far away, now to the right, now to the left, and anon directly above me. To my ear it was a new kind of bird minstrelsy. I climbed higher and higher, and yet the song seemed to be no nearer. It had a grosbeak-like quality, I fancied, and I hoped to find either the pine or the evening grosbeak, for both of which I had been making anxious search. The shifting of the song from point to point struck me as odd, and it was very mystifying.