Approximately 220 species of wild mammals occur in California
and the surrounding waters (including introduced species, but
not domestic species such as house cats). Amazingly, the state
of California has about half of the total number of species that
occur on the North American continent (about 440). In part, this
diversity reflects the sheer number of different habitats available
throughout the state, including alpine, desert, coniferous forest,
grassland, oak woodland, and chaparral habitat types, among others102,
About 17 mammal species are endemic to California; most of these
are kangaroo rats, chipmunks, and squirrels.
Nearly 25% of California’s mammal species are either known
or suspected to occur at Quail Ridge (See
Mammal List). Species found at Quail Ridge are typical of
both the Northwestern California and Great Central Valley mammalian
faunas. Two California endemics, the Sonoma chipmunk (see Species
Accounts for scientific names) and the San Joaquin pocket mouse,
are known to occur at Quail Ridge. None of the mammals at Quail
Ridge are listed as threatened or endangered by either the state
or federal governments, although Townsend’s big-eared bat,
which is suspected to occur at Quail Ridge, is a state-listed
species of special concern.
mammal species are nocturnal, fossorial, fly, or are otherwise
difficult to observe. However, it is still possible to detect
the presence of mammals at Quail Ridge, both visually and by observation
of their tracks, scat, and other sign. The mammals most often
seen during the day are mule deer and western gray squirrels.
Mice and rats are nocturnal and thus not often seen, although
the large stick-houses of dusky-footed wood rats are apparent
in oak woodland and riparian habitats. Carnivores such as mountain
lions, foxes, and bobcats may be detected by the presence of scat
and tracks left in mud or dust on the dirt roads. Black bear sign
has even been observed, including claw marks on an abandoned truck
on the west side of the peninsula, and bear tracks were found
in the road leading into Decker Canyon in May 2003. Different
species of mammals are found in the various plant communities
at Quail Ridge. In chaparral, rodents such as brush mice, wood
rats, and harvest mice are common. Ground squirrels, pocket gophers,
harvest mice, and voles inhabit grassland habitats. Wood rats,
gray squirrels, skunks, raccoons, and deer mice may be found in
woodland habitats. Larger mammals such as mule deer, coyotes,
bobcats, and mountain lions may be spotted across Quail Ridge.
Some small mammals, such as deer mice and brush mice, can be found
in more than one habitat type.
Potential Research Topics
Little research has been conducted on the mammals of Quail Ridge.
Mammalogy students from the University of California, Davis have
live-trapped small mammals in riparian areas of Decker Canyon,
and in chaparral near the research station. Karen Mabry, a UC
Davis animal behavior graduate student, is studying the dispersal
and habitat selection behavior of brush mice from oak woodland
and chaparral habitat types.
questions about the mammals of Quail Ridge remain totally unanswered.
As only 18 of the 58 species that may occur at Quail Ridge have
actually been confirmed, a general survey of mammalian diversity
would be extremely helpful. The bats are particularly understudied,
in part because of the difficulty of observing flying, nocturnal
animals, and the need for technology (e.g., ultrasonic bat detectors)
to detect their calls, which can be undetectable to human ears.
Quail Ridge is especially suited for a study of predator/prey
dynamics; small mammals such as mice, rats, and voles are very
abundant and form a prey base for a large number of mammalian
and avian predators. At least two, and possibly three, species
of Peromyscus mice coexist at Quail Ridge – what ecological
factors allow such similar and closely related species to coexist?
Large carnivores such as mountain lions may be particularly disturbed
by human activities; human impacts at Quail Ridge are relatively
minor compared to the surrounding areas. Does the presence of
large tracts of protected land at Quail Ridge positively affect
these animals? These are just a few of the many potential research
projects that could be conducted with the mammals of Quail Ridge.