Finding Digs for Endangered Small Mammals in Southern California

Kangaroo rats and pocket mice are considered keystone species that influence ecosystem processes in desert, shrub, and grassland ecosystems. They are responsible for dispersal of native grass seeds, soil disturbance, and nutrient cycling, and they are prey to several top carnivores.

Because of the current status of these species and continued development of Southern California, it is vital that efficient and effective reintroduction and translocation methods be designed and implemented.

Our long-term objective is to aid in the recovery of the critically endangered Pacific pocket mouse and the federally and state-endangered Stephens’ kangaroo rat by establishing several new viable populations on protected lands via translocation and conservation breeding and reintroduction. 

For pocket mice, the last few years have been extremely dry, and limited rainfall has meant low seed production and a significant contraction of the largest remaining population. Because of low numbers of animals, translocation has not been an option for this species.

Our hope is to begin a conservation breeding program at the Wild Animal Park to produce individuals for eventual reintroduction onto Camp Pendleton and possibly other locations in their historic range. We plan to begin trapping to bring animals into managed care for breeding in the spring and to reintroduce approximately 50 animals by mid-summer. If our methods prove effective this year, we will establish a second population at the nearby Dana Point Headlands in Orange County in 2010. 

For kangaroo rats, we conducted a translocation in the summer of 2008. We examined whether moving neighboring animals together would increase their survival following release. We are currently working with the Riverside County Habitat Conservation Agency and reserve managers to remove exotic grasses and restore preferred habitat on the reserves.

The most immediate goal for this species is to continue post-translocation monitoring and assessment and establish endocrinology methods to assess stress. A second translocation project is planned for this summer (2009).

This research will serve as a model from which translocations can be designed for other imperiled solitary rodent species in California and facilitate restoration of desert, grassland, and shrub ecosystems in which they play an important role.