Karen Mabry, Dispersal and habitat selection behavior of brush
mice
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.
 To
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)
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