Natural habitats in the valley and foothill areas of coastal southern California have been diminished over the past century as a result of intensive human development and sprawl. The loss, conversion and fragmentation of native vegetation have altered animal communities throughout the region as well, leaving populations isolated from one another and the remaining open space in the surrounding mountains and parks.
The Bernard Field Station (BFS), located in Claremont, California, is a 38-ha tract of scrub, woodland and grassland habitat embedded in a matrix of residential and commercial development. Expansion of Interstate 210 in 2002 approximately 0.5 km north of the BFS further isolated native plant and animal communities from the nearby San Gabriel Mountains.
Rodent populations at the BFS haved been studied occasionally by students taking courses at the Claremont Colleges, e.g., Dr. Nina Karnovsky's studies of woodrats (http://pages.pomona.edu/~njk04747/woodrat/), but information on population densities and microhabitat associations of other rodents is not widely available. As part of our Mammalogy course at Cal-State Fullerton, we live-trapped rodents over three nights in March 2010 to
determine what rodent species were abundant in representative habitats at the BFS and to determine if species tended to be associated with particular microhabitat features.