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Jan., 1919 BIRDS REMAIN MATED i?OR A NUMBER O1? YEARS 29 .I find the Flycatchers very persistent also. One pair of the Ash-throated (Myiarchus cinerascens cinerascens) has returned to the same old cavity in an oak tree for the past four seasons, while several other pairs I have watched have each nested two or three times in their own particular stump or cavity. A change by them is generally caused by the old site being destroyed. Our Black Phoebe (Sayornis nigricans) having once built a nest will return the following year and use it again after supply?.ng a new lining. This I have found to be the case a number of times. I have seen nests of our Western Kingbird (Tyrannus verticalis) two and three stories high, indicating the number of years the nest had been used. Mr. Willard's experience with the Cabanis Woodpecker (Dryobates villosus ?yloscopus) is identical with mine. In 1917 I collected a set from a stump that held three other perfect excavations of previous years. This was a small dead cottonwood not over ten feet high, and though there were a great many other similar stumps in the grove, this was the only one that I could locate that con- tained an excavation of this species. Our Roadrunners (Geococcyx californianus) lay in their chosen cactus patches each year and I have taken as many as three sets from the same nest in successive years. The Raven (Corvus corax sinuatus) can be counted on to re- tarn to the old home each year, but if disturbed a new nest is usually built the next spring in another ledge or crack nearby. Members of the sparrow family as a rule are more uncertain, although they return to the same general locality. This is due, I think, to the nature of the location where their nests are placed; for, if substantial forks or hollows were used, I believe we would find the birds returning to the identical spot on suc- cessive years. To illustrate the point:' Some eight years ago I ran across a few clumps of bunch-grass growing on the side of a steep ravine, under one of which was a slight depression in the hard decomposed granite soil. This was almost hidden by the overhanging grass, and a number of broken eggshells of the Val- ley Partridge were lying about, showing that a family had been raised there. It appeared to be an ideal spot for the home of g Rufous-crowned Sparrow (Aimo- phila ruficeps ruficeps). Each year, when in this locality, I examined the spot, but not until 1917 was I rewarded. That year the cavity contained a nest and four young of this sparrow. The past spring I was on the ground. early, and sure enough the site held a nest and four eggs of the species. I find the L?ast Vireo (Vireo belli pusillus) very persistent in returning to the same clump of trees to nest, and have taken several sets within a foot or two of the spot where the nest of each previous year had been suspended. The Plain Tit-mouse (Baeolophus inornatus) offers a good study along this line. While living at Palo Alto some years ago I had a pair that laid nicely spotted eggs, and I was able to collect two sets on successive years from this pair. The nest each time was built in the same cavity of a live oak. You can be sure that I would return and look at that hollow if I ever were near Palo Alto at the proper season, although the last set I took was ten years ago. The Raptores offer the best and most easily followed of any of the orders. A pair of Golden Eagles (Aquila chrysaetos) I have in mind was watched quite closely for eighteen years. The female of the pair when first encountered was quite old and very white. After a number of years the type of eggs suddenly changed and a dark colored bird was found in possession of the home. The old female can still be seen hunting by herself just off the old range, being easily