Observations on the California Mastiff Bat

Abstract

The mastiff bat is one of the largest and most impressive Chiroptera inhabiting North America. Eumops perotis californicus occurs most abundantly in southern California but its range also includes southern Arizona, western Texas and north-western Mexico. Much of our present knowledge of the life-history of this bat stems from work by H. W. Grinnell (1918), A. B. Howell (1920a, 6), A. B. Howell and L. Little (1924), P. H. Krutzsch (1943, 1945), and W. W. Dalquest (1946). The present paper synthesizes the foregoing citations and adds additional data. Many of the observations presented here were made in San Diego County, California and were gathered intermittently through most of the years 1935 to 1943 and in the summer months (June to September) of 1946, 1948, 1949, 1951, and 1953. I wish to acknowledge the assistance of Messrs. K. Dixon, C. Engler, J. R. Homesley, R. Neil, and A. C. Olson, Jr., all of whom accompanied me at one time or another in search of these bats. Thanks are also due Drs. S. B. Benson and Hildegard Howard for permission to examine material in their care. Eumops perotis calif ornicus is a species of the Lower and Upper Sonoran life zones and has been found in cultivated areas, in rocky places where chaparral and live oak intermingle, and in more arid, rocky situations where vegetation is sparse. Mastiff bats utilize a variety of roosting places: Von Blocker (1932) records one which was found hanging in a black acacia tree; Stephens (1906) lists a signboard and a tunnel as roosting sites; Howell (1920a, 6) records several old buildings (either stone or wood) as roosts; Krutzsch (1943, 1945) and Dalquest (1946) report having found them in crevices in rocks; and we have one taken from under a …