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May, 1909 THE USE OF MAGPIES' NESTS BY OTHER BIRDS 91 follow an owl into an abandoned nest, and seem utterly at a loss to understand the prompt disappearance of the object of their pursuit. It is, however, in furnishing an ideal nesting site for several species of birds that the magpie bestows his greatest gift upon his bird neighbors. As has been mentioned before the two species whose occupancy of magpie's nests is most prevalent are the Long-eared Owl and the Western Horned Owl. Both of these birds are notoriously averse to anything that bears a semblance to work, and the substantial last year's nests of the magpie furnish an ideal recepta- cle for the great white eggs and the fluffy youngsters. Very little repairing is done to the abandoned structure preparatory to laying the eggs. A few feathers from the parent's breast, and possibly those of some bird which has fallen a prey to the owl, to- gether with the accumulation of dead leaves, dirt and refuse found in old nests, form the "lining" upon which the eggs are laid. Capt. Bendire in his "Life Histories" states that the Western Horned Owl de- posits its eggs "occasionally inside but more often on the broken-down roof of these bulky structures." This state- ment will probably apply equally well to the Long-eared Owl as I have yet to find the first set of these eggs laid in a magpie's nest which was domed over, altho the owls frequently make use of the interior of rooft nests as hid- ing places. Owing to the nature of the timber thruout a large portion of western America the great majority of magpie's nests range in hight from 15 to 25 feet above ground, altho occa- MAGPIE'S NEST APPROPRIATED Bvff A PAIR OF SPARROW HAWKS NEAR DENVER, COLORADO sional nests are encountered ranging upward to at least 60 feet above ground. However, the high nests do not seem to be preferred by the above mentioned species, or in fact by any of the following mentioned species and it is safe to say that prac- tically all birds occupying magpie nests utilize nests varying from 15 to 30 feet above the ground. The Rocky Mountain Screech Owl, like all of the genus Otus, nests almost entirely in natural cavities or deserted woodpecker's nests and I have never been fortunate enough to discover a nest in any other situation; but Bendire in his