BURROWING OWL. Speotyto cunicularia hypogaea (Bonaparte)

Field characters.—Size small for an owl; about twice bulk of Meadowlark; head rounded, no ear tufts (fig. 39i). Plumage light brown and white in mixed pattern; eyes yellow. Voice: A mellow two-syllabled call, cuck-oo, uttered over and over again; heard most often at dusk during the spring months.

Occurrence.—Common resident in Lower and Upper Sonoran zones; noted by us only west of Sierra Nevada. Lives in open country in and about ground squirrel burrows.

The Burrowing Owl, locally known as 'billy owl,' and perhaps better called 'ground owl,' is to be looked for confidently on the plains of the San Joaquin Valley and on such larger tracts of level land as are to be found among the foothills. Living in the open and being active during part of the day as well as all the night, this owl is likely to be seen by anyone traversing its habitat. It frequents the vicinity of ground squirrel burrows, both for shelter and for nesting sites.

Occasionally individuals are to be seen perched on fence posts at the edges of fields or pastures, and from these vantage points they watch for insects in the surrounding grasslands. As a person walks past at close range the owl turns its head so as to keep the passerby under constant surveillance; should the observer circle about the bird, the latter seemingly finds no difficulty in rotating its head, even so as to look directly over its own back. The dexterity of the bird in this respect has given rise to the popular belief that it can twist its head entirely around several times without inconvenience! A curious mannerism of this owl is a profound bow executed at irregular intervals.

Nests of the Burrowing Owl are situated in squirrel burrows, at varying distances from the entrances, but usually far beyond arm's length. The birds make use of damp horse manure almost exclusively in making the nest proper, hence a scattering of this material seen during the spring months at the entrance to a squirrel hole may be counted on as an indication that a pair of Burrowing Owls has a nest within.

Burrowing Owls are more prolific than tree-nesting species of owls, doubtless because they are more subject to enemies than the latter species. Late in summer family groups of as many as a dozen individuals are occasionally seen within the radius of a few yards.