Ecology of pocket gophers with emphasis onThomomys bottae mewa

The life history and ecology of the Digger pine pocket gopher (Thomomys bottae mewa) are here reported. Most of the data were obtained by live-trapping for five years 330 marked individuals 1,798 times on a 3.7-acre study plot at the San Joaquin Experimental Range, O’Neals, California. In all, more than 1,000 gophers were studied, many of which were maintained in various types of laboratory cages. Body weight is not a reliable indication of age since males continue to grow throughout their life and the alimentary tract of seven gophers averaged one fifth of their gross body weight. Males do not live as long as females, which often live for three or four years. Gophers apparently are frequently polygamous. The adult sex ratio of males to females varied from about 1:1 to 1:4. Females predominated (1:4) when the population density was high. The home range of a pocket gopher is also its “territory,” for adults vigorously defend their entire burrow system from others of both sexes, except during the breeding season. Male territories occupied an average surface area of 2,200 square feet, whereas females only one half that, or 1,300 square feet. Young gophers often left home by dispersing aboveground. More than 200 were captured in funnel traps on the ground surface along hardware-cloth drift fences. Gophers released 200 or more feet from their burrow were able to return home by traveling through existing burrow systems. The ecological factors responsible for creating fluctuations in the density of gophers are discussed. Also discussed are the signifiance of pocket gophers with respect to animal associates, soil and forage relationships, effect of burrows, and importance to man.