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 104 VOL. XlI THE OLIVE WARBLER (DEND2?OICA OLIVACEA) IN SOUTHERN ARIZONA By 1,. C. WILLARD WITH TWO PHOTOS MONG the pines of the open forest which covers the summits of the Huachuca Mountains several species of our rarer birds make their summer homes, and they are seldom seen or heard in other parts or lower levels of the mountains. The Olive Warbler (Dendroica olivacea) is perhaps the most sought after of these summit dwellers. It is also one of the rarest and most easily over- lookt. They seem to arrive some time about the 10th of May, and the first few days are spent, as it were, in staking out their claims anew. The males at this time are quite pugnacious toward one another, and, tho apparently already mated, they promptly drive any wanderer of the same sex from their selected bit of forest. I believe they return each year to the same locality in which they made their home of the previous year, as I have found them in the same patch of trees year after year while other places near by, with the same apparent advantages, never seem to be chosen. About the 20th of May nest building begins. The nest is a very handsome and compact affair. It is built by the female alone and she requires about two weeks for its construction. ' The male accompanies her as she flies to and fro gathering the materials. He calls and sings as they work and it is at this time it is best to locate the nest, as it is so well concealed that after it is completed the sharpest eyes cannot penetrate the clump of needles in which it is placed, and the sitting bird cannot be induced to leave her nest unless called off by the male, or when she goes to feed. The well concealed nest is the usual thing tho I have seen several that were quite conspicuous. ShortLl.eaf pines, long-leaf pines and firs are chosen for the nesting sites. Up to the season of 1909 I had always found them in long-leaf pines, perhaps because I always looked there for them. This season one was in a fir and the balance in short-leaf pines. On May 24 the female was observed building the nest found in the fir tree. She was gathering rootlets at the time and seemed very particular about them, picking up and dropping several before selecting one which she thought satisfactory. This she carried into a dense growth at the tip of a branch of a large fir about one hundred yards away. The male was singing and feeding in a tree close by. After' a few trips with material the female would fly into the tree where he was and let him feed her. This is the only time I have observed nest building going on and the male not foil.owing the female in her flights. This nest was apparently well along in its construction as on June 3 1 collected it and a set of four fresh eggs. At this time the male was not seen or heard around the nest, nor would the female flush until I climbed the tree and shook the branch with considerable violence. As there was but a light wind blowing, I roped the branch up, and, crawling out, cut off a few of the intervening twigs so as to get the nest in view. Then I hauled up my camera and fastened it in position eight feet from the nest. During all this procedure the female was hopping around close by, and the male, responding to her calls, came tc investigate, and remained near by until I collected the set. After everything was in readiness, I crawled back to the trunk and mad, myself as comfortable as possible to wait Madame Olive's return to her nest. In 