OWLS AND FIELD MICE.
Owls as destroyers of mice are deserving of special mention. Not one of our American owls, unless it be the great horned owl, is to be classed as noxious. Especially beneficial are the short-eared, long-eared, screech, and barn owls. All these prey largely upon field mice, and seldom harm birds. Unfortunately, the short-eared and barn owls, which are the more useful species, are not plentiful in the sections most seriously infested by field mice.
The short-eared owl, while widely distributed, is not abundant, except locally, within the United States, but wherever field mice become excessively numerous these owls usually assemble in considerable numbers to prey upon them. Examinations of stomachs of these owls show that fully three-fourths of their food consists of short-tailed field mice.
The barn owl is rather common in the southern half of the United States and breeds as far north as the forty-first parallel of latitude. That mice form the chief diet of this bird has been demonstrated by Dr. A. K. Fisher, of the Biological Survey, through examination of stomachs of many barn owls and also of large numbers of pellets (castings from their stomachs) found under their roosts. In 1,247 barn-owl pellets collected in the towers of the Smithsonian Building in Washington, D. C., he found 1,991 skulls of short-tailed field mice, 656 of the house mouse, 210 of the common rat, and 147 of other small rodents and shrews. Very few remains of birds were found. Figure 7 illustrates the contents of some of these pellets.
Fig. 7.—Field-mouse skulls taken from pellets found under owl roost in Smithsonian tower, Washington, D. C.
In 360 pellets of the long-eared owl Dr. Fisher found skulls of 374 small mammals, of which 349 were meadow mice. Stomach examinations give similar testimony to the usefulness of this bird.
The common screech owl, in addition to feeding mainly upon mice, destroys also a good many English sparrows. Its habit of staying in orchards and close to farm buildings makes it especially useful to the farmer in keeping his premises free from both house and field mice.
WASHINGTON: GOVERNMENT PRINTING OFFICE: 1915
Transcriber's Note:
Every effort has been made to replicate this text as faithfully as possible.