Neither of these hypotheses is free from objection, for, on the one hand, it is not likely that birds, which cannot see in the dark, would take the risk of dashing their brains out against the cliffs and crags of the cañons by following them at night; yet they may depart from their usual habit of nocturnal migration, and make the journey up the gorges and vales by day. On the other hand, the nights are so cold in the elevated regions that the little travellers' lives might be jeopardized by nocturnal flight over the passes and peaks. There is one thing certain about the whole question, perplexing as it may be--the feathered pilgrims reach their summer quarters in some way, and seem to be very happy while they remain. We stopped at a number of places in our run down South Platte Cañon, adding no new birds to our list, but making some interesting observations. At Cassel's a house-wren had built a nest on the veranda of the hotel where people were sitting or passing most of the time, and was feeding her tiny brood. In the copse of the hollow below the resort, the mountain song-sparrows were trilling sweetly--the only ones we had encountered in our wanderings since leaving Arvada on the plains. These musicians seem to be rather finical in their choice of summer resorts. Chaseville is about a mile below Cassel's, and was made memorable to us by the discovery of our second green-tailed towhee's nest, a description of which I have decided to reserve for the last chapter of this volume. Lincoln's sparrows descanted in rich tones at various places in the bushy vales, but were always as wild as deer, scuttling into the thickets before a fair view of them could be obtained. The veranda of a boarding-house at Shawnee was the site of another house-wren's nest. While I stood quite close watching the little mother, she fed her bantlings twice without a quaver of fear, the youngsters chirping loudly for more of "that good dinner." At this place barn swallows were describing graceful circles and loops in the air, and a sheeny violet-green swallow squatted on the dusty road and took a sun-bath, which she did by fluffing up all her plumes and spreading out her wings and tail, so that the rays could reach every feather with their grateful warmth and light. It was a pretty performance. [Illustration: _Violet-green Swallow_ "_Squatted on the dusty road and took a sun-bath_"]