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Western Ecological Research Center
Field Station of the Biological Resources Division- USGS
The United States Geological Survey(USGS, Western Ecological
Research Center) has a field station at Point Reyes National
Seashore. USGS is conducting research on the population status
and ecology of California red-legged frog and Point Reyes
Mountain Beaver. USGS is also conducting an inventory of terrestrial
vertebrates, including amphibians, reptiles, small mammals,
and bats.
California Red-legged Frog Monitoring
Point Reyes Mountain Beaver Monitoring
Multi-Species Inventory and Monitoring
Bat Research
Additional
information on the Point Reyes Field Station (PDF
441 KB)
Summaries:
California Red-legged Frog Monitoring
Overview
The California red-legged frog (Rana aurora draytonii)
is the largest native frog in the western United States. It
was federally listed as threatened in 1996, partly because
it has disappeared from 70 percent of its former range. This
frog is now is found primarily in coastal drainages of central
California. Potential threats to the frog include elimination
or degradation of habitat from land development, and habitat
invasion by nonnative aquatic species. Pesticide drift from
the agricultural use of pesticides may also be contributing
to the decline in the Sierra foothills.
The USGS field station at Point Reyes has several ongoing
research projects that focus on this frog. Since 1993, every
pond and several streams at Point Reyes have been surveyed
for red-legged frogs. In the breeding season (winter), the
location and number of egg masses are recorded. Throughout
the year, individual frogs are radio tagged and tracked to
determine non-breeding behavior, habitat use at breeding sites,
and to monitor dispersal habits in the Olema Valley. Frogs
are also tagged with small electronic microchips that are
placed under the skin. These tags work like a barcode allowing
researchers to identify and record specific data about an
individual frog. Selected sites have been surveyed more closely
in order to document population trends. Currently there are
more than 50 known breeding sites at Point Reyes. Information
on the ecology, distribution, and population status of red-legged
frogs is being used to develop more effective management strategies.
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Point Reyes Mountain Beaver Monitoring
The Point Reyes mountain beaver is a unique subspecies that
exists almost exclusively within Point Reyes National Seashore.
Surveys have been conducted since 1983 to determine the distribution
of mountain beaver within the park. These data became particularly
valuable after the 1995 Vision Fire burned a significant portion
of the habitat for the Point Reyes mountain beaver. Subsequent
to the fire, USGS biologists determined that less than 5%
of the mountain beaver within the burn area had survived.
Ongoing monitoring is documenting the slow recovery.
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Multi-Species Inventory and Monitoring
Overview
USGS biologists are conducting an inventory to determine
what species of amphibians, reptiles, and small mammals are
present within Point Reyes National Seashore. The results
of this work will provide Point Reyes NS with better information
on what animals are present within the park. The inventory
will also provide the foundation for a long-term monitoring
of key park resources. Without a knowledge of what species
are present, and what trends are occurring in key species,
the National Park Service will not be able to properly manage
the natural resources.
Amphibians, reptiles, and small mammals are captured using
several live trapping techniques including artificial cover
boards, pitfall traps, and Sherman live traps. Animals are
identified, weighed, measured, and released at the site of
capture. Some species are given individual tags so that they
can be recognized on subsequent captures. This allows biologists
to assess movement, growth, and longevity. Trapping arrays
have been established in various habitats within the park
to assess habitat preferences.
Medium-sized animals are inventoried with the use of remote
triggered cameras, thus avoiding the necessity more expensive
capture techniques. Incidental photographs of birds and other
species augments other survey techniques. Over 12,000 photographs
have been accumulated thus far (November 1995 -August 2000),
representative of 58 species. Some of the highlights included
1,284 photographs of bobcats, 47 photographs of badgers, and
26 photographs of mountain lions.
The initial inventory work extended over three years and
focused on eight sites in five habitats (bishop pine, Douglas
fir, riparian, grassland, and coastal scrub). As the inventory
draws to a close, many of the inventory sites will be utilized
as long-term monitoring sites. Monitoring will allow the park
to assess changes in distribution, habitat preference, and
(in some cases) abundance of key species. All this information
is important for assuring that the park is being managed in
a fashion that protects the natural resources.
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Bat Research
Research on bats at Point Reyes has centered around two
main projects. One has been an ecological study of Townsend's
big-eared bat, and another is an inventory of bats that occur
at Point Reyes.
Townsend's big-eared bat is a rare bat that has become much
less common in the last 25 years. In 1987, a small maternity
colony was found in an abandoned building at Point Reyes.
Subsequently, Point Reyes National Seashore protected this
colony from disturbance, and the population of rare bats increased
from about 75 to 200. USGS has monitored the bat colony since
its discovery, and has conducted additional research on the
foraging habits of these bats.
As shown by the discovery of Townsend's big-eared bat, there
can be rare and endangered species living within a protected
area without the knowledge of the land managers. Hence, an
inventory of bats is underway to determine what species occur
within Point Reyes NS and to evaluate seasonal activity and
habitat preference. This work has been accomplished with a
combination of capturing bats at night (using harp traps and
mist nets), and acoustic monitoring of bat vocalizations at
a series of monitoring stations. Acoustic monitoring uses
sophisticated electronic equipment that records ultrasonic
vocalizations, and stores them in a format that can be transferred
to a computer. Software is being developed that will allow
a computer program to scan through the thousands of files
and provide summaries of the species of bats that were in
the area. This pioneering technique is also being deployed
at other National Park areas in the region.
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