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 I42 THE CONDOR VoL. IX on the ground, this owl begins preparation for its nest building, which, by the way, is sisnple in the extreme. The snonth of April is the usual tisne for fresh eggs; and to be snore precise than this as to date is hardly possible, as I have found fresh eggs as common during the first week of April as the last, and I am led to believe that the nesting date is governed largely by climatic conditions. Moreover, the nesting season is not confined to the month o April by any means, and nests with eggs have been found as late as the 30th of May. This is, however, an extreme date and is undoubtedly the result of an accident of some kind. HOME OF ROCKY MOUNTAII' SCREECH OW'L; WALL CUT AWAY TO SHOW NEST CAIT in box-elder or black willows, the cottonwood rarely Captain Bendire in his incomparable work on North As has been stated before the nesting site is invariably along the well wooded water- courses and i1 snore or less dense groves of cottonwoods and occasionally willow or box-elder. A peculiar char- acteristic of this bird is its predilection for sluggish or stagnant water, and one of the prerequisites of a model nesting site is a small slough or pool within a short dis~ rance of the nest hole. I am at a loss to know why this is so, uuless it is that frogs and crawfish forln no inconsider- able portion of the bird's food, and close proximity to a source of food supply may be a solution of the problem. The very great majority of nests are fotmd in cottonwood trees. This is probably due to the fact that this tree greatly predomilmtes along all the foothill streams, and it is the variety most colnmonly used by the Red-shafted Flicker, the deserted excava- tions of which the Screech Owl nearly always occupies. However, natural cavities are occasionally resorted to; but owing to the nature of the trees these are found mostly rotting out in this manner. American Birds, states that the birds occasionally lay in the deserted nests of the Magpie. The size of the cavities and entrances to the same naturally vary greatly. The Screech Owls do not excavate at all, but simply preempt the cavities as they are. It is extremely rare, however, that a nest is found in a cavity which is exposed to the elements, great care evidently being used to select a cavity which is more or less