Karen Mabry, Dispersal and habitat selection behavior of brush mice

Brush mouse; Photo by Karen Mabry My research focuses on how brush mice move through different habitat types, and how their movement patterns and habitat selection are affected by their experience. Animals may prefer familiar habitat because experience makes them more efficient in using resources. The tendency of dispersing animals to settle in the same habitat type they were reared in has been called habitat imprinting or habitat preference induction. Habitat imprinting may influence the maintenance of genetic variation, withinspecies behavioral diversity, and the dynamics of populations in spatially complex habitats.

The Quail Ridge Reserve is an ideal location to study this because there are abrupt transitions between oak woodland and chaparral, and brush mice (Peromyscus boylii) are abundant in both of these habitats. Individual brush mice may be reared in either oak woodland or chaparral, but may disperse to and settle in either habitat. Oak woodland is dominated by interior live oak and California bay, and has an open understory and thick canopy. Chaparral is a dense, shrubby mixture of chamise, toyon, and scrub oak, usually less than 3 m high.

Weighing a brush mouse; Photo by Karen MabryTo compare population densities and demographic parameters between oak woodland and chaparral, I am livetrapping mice across habitat boundaries. To track juvenile mice born in both habitats, I use radio-telemetry. I spend many nights at the Reserve tracking mice during January - June, when most juvenile dispersal takes place, and I plot the radio-locations of each individual on the Napa County Vegetation Map. These data will allow me to determine if movement patterns are affected by habitat itself, or by familiarity with a habitat, and whether dispersers tend to use and settle in their natal habitat more often than expected by chance.

In addition to continuing the live-trapping and radio-telemetry, in 2004-2005 I plan to use microsatellite DNA markers to investigate relatedness among brush mice, and to determine the natal home ranges of juveniles by assigning them to mothers. I also plan to use fluorescent powder tracking to obtain movement paths at a finer scale than can be obtained by radio-telemetry. I will use these paths to explore the effect of habitat type and familiarity on movement parameters such as path complexity, total distance traveled, and movement speed within each habitat.

Not only is Quail Ridge an excellent site for my study, but the GIS data and vegetation maps provided by the NRS staff have been invaluable. The NRS staff helped me locate my sites, and since these sites were far from the field station, they moved a camper out there so I would have a place to stay between telemetry readings on cold spring nights. My research would have been very difficult without the resources and support provided by the UC Natural Reserve System.

Photo Credits: Title, Research (Mike Benard), mouse with collar and mouse being weighed (Karen Mabry)

This page last updated: June 23, 2005  

Contact: Dr. Virginia Boucher
John Muir Institute of the Environment
109 The Barn, University of California, Davis, CA 95616
Phone: 530-752-6949; email: vlboucher@ucdavis.edu

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