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 The
sagebrush habitat of eastern Washington's
Columbia Basin is vanishing, and so is Washington's
only population of pygmy rabbits [Brachylagus
idahoensis], the country's smallest
native rabbit and the only one to dig its
own burrows.
Although
the rabbit has been listed for protection
as a state endangered species since 1993,
and is federally listed as a species of concern,
its numbers have continued to plummet. Prompted
by the rabbits' dramatic decline in Washington
and recent Washington Department of Fish and
Wildlife (WDFW) genetic analyses, the U.S.
Fish and Wildlife Service has taken the rare
step of initiating a federal status review
for potential emergency listing of the pygmy
rabbit as threatened or endangered. Meanwhile,
WDFW has spearheaded an emergency captive
breeding program as well as habitat enhancement
to restore the pygmy rabbit to viable levels.
Washington's
pygmy rabbits unique
The pygmy rabbit is found in many locations throughout the Great Basin
region of the western United States, but the Washington population is
geographically isolated from the rest of the species range, and is genetically
distinct. Dr. Kenneth Warheit, a WDFW research scientist, has conducted
genetic analyses of pygmy rabbits from Washington, Oregon, Idaho and
Montana. His results suggest that the Washington population has not only
been isolated from other pygmy rabbit populations for an extended period
of time, but has also experienced a dramatic loss of genetic variability
possibly due to inbreeding.
 Historically,
Washington pygmy rabbits occurred in native
shrub-steppe throughout five counties: Adams,
Grant, Douglas, Benton and Lincoln. By 1997,
just six populations remained. Last year,
three small populations were left, all in
Douglas County. This year, field surveys by
Nikki Siegel of Washington State University
(WSU) and WDFW biologists Tom McCall and John
Musser found rabbits at only one site, Sagebrush
Flat, and the number of animals there had
declined dramatically as well. The number
of animals there had declined dramatically
as well. After trapping a dozen rabbits from
Sagebrush Flat to initiate captive breeding,
few, if any of the animals remain in the wild..
Wildlife
scientists believe that habitat loss and fragmentation
are the principal factors that have resulted
in the long-term decline of pygmy rabbits
in Washington. Specific reasons for the recent
sharp declines are not known, but may include
disease, predation, or may be a result of
small population size. Pygmy rabbits require
deep loamy soils to dig their burrows and
depend heavily on sagebrush, which they feed
on almost exclusively in winter months. But
the sagebrush is vanishing as the native shrub-steppe
of the Columbia Basin has been converted to
agricultural use. Fire is another factor which
is playing a role in the decline of pygmy
rabbits.
 Emergency
program seeks to preserve population
With the collapse of the state's pygmy rabbit population apparently imminent,
wildlife biologists decided last May to remove rabbits from the wild
to a captive breeding facility in a last-ditch effort to prevent extinction.
The goal of this emergency captive breeding program is to ensure that
Washington's genetically unique population of pygmy rabbits is maintained
by producing sufficient numbers of rabbits to re-establish populations
in suitable wild habitat.
The captive breeding effort is part of a recently completed WDFW emergency
action plan. The breeding program follows earlier efforts, carried out
under a 1995
WDFW recovery plan that included habitat acquisition, extensive surveys
and monitoring and two graduate-student studies of pygmy rabbit ecology
and habitat relationships and predator control.
 The
captive breeding project is expected to be
conducted for five or more years. The objective
is to produce approximately 100 or more pygmy
rabbits each year and release them back into
the wild. Female rabbits can produce up to three
litters per year with four to six young in
each litter.
Besides
the captive breeding and release program,
the emergency plan calls for securing funding
to provide contiguous shrub-steppe habitat,
addressing other risk factors and expanding
public education about the rabbits' fragile
situation.
A
Science Advisory Group has been established
to review and advise on the progress of all
aspects of recovery, including the captive
breeding effort. The group includes WDFW Wildlife
Program Chief Scientist John Pierce, representatives
from the U. S. Fish and Wildlife Service,
universities, and experts in captive breeding
and conservation genetics, and species survival
plan experts from the American Zoological
Association. The group will review genetic
analyses and provide recommendations to WDFW
on the captive rearing program and allocation
of resources for pygmy rabbit recovery.
The
cornerstone of the emergency recovery effort– the
captive breeding program– involves several
major steps:
- Before
captive breeding could begin, wildlife scientists
needed to develop husbandry techniques for
pygmy rabbits, which had never before been
reared in captivity. For this phase of the
project, WDFW worked with the Conservation
Program at the Oregon Zoo in Portland. Dr.
David Shepherdson of the Oregon Zoo had
cooperated with WDFW in the past on the
Western pond turtle and Oregon silverspot
butterfly recovery programs.
To obtain an experimental population for the husbandry study, project
scientists received permission from the state of Idaho to capture Idaho
pygmy rabbits. Working with Idaho Fish and Game and the Bureau of Land
Management, four Idaho pygmy rabbits were captured and brought to the
Oregon Zoo in December, 2000 for the husbandry study. Results of the
project have enabled wildlife biologists to determine suitably sized
rearing pens for the rabbits, proper foods at different times of the
year and special needs of the rabbits during the breeding season. The
zoo installed video cameras in the rabbit enclosures and uses the cameras
to observe behavior, nesting and reproductive activity. During the
husbandry study, three litters of young rabbits were born. Wildlife
biologists plan to release some of the young rabbits back into Idaho
to learn more about effective release methods.
- Next
came the actual capture of Washington pygmy
rabbits. To collect the rabbits, WDFW biologists
Tom McCall, John Musser and Laura Cooke
located rabbits at Sagebrush Flat and placed
traps at burrow entrances after the rabbits
went into the burrows. They checked the
traps every 10 to 20 minutes, and caught
the rabbits as they emerged. As each animal
was caught, it was immediately removed from
the trap, sexed and placed in a pet carrier
with grasses and sagebrush.
- The
captured rabbits - seven adult females and
five adult males – were immediately
transported to Washington State University
where they were placed in a quarantine facility
under the direction of Dr Lisa Shipley,
Dr. Rod Sayler, and graduate student Nikki
Siegel. After examination by a veterinarian,
the animals were treated for fleas and the
fleas were collected for disease testing.
A passive integrated transponder (PIT) tag,
a small, coded piece of metal which can
be scanned electronically to identify an
individual animal, was inserted under anesthesia
beneath the skin between the shoulder blades
of each of the rabbits. Within the first
two weeks of captivity, a complete disease
work-up was performed on each rabbit while
the animal was under anesthetic. After about
three weeks in quarantine, the rabbits were
transferred to outdoor pens. Ramps connect
individual pens, allowing male and female
rabbits access to each other during breeding
season. Initially, animals were weighed
on a weekly basis until they began to gain
weight. After that they are weighed monthly.
In April 2002, monitoring of birthing will
begin using direct observation and remote
video cameras. WSU staff will rely on earlier
captive breeding work by the Oregon Zoo
to determine when young need to be separated
from adult rabbits. Offspring to be used
for release will receive minimal human contact.
- Genetic
analyses are underway to determine the numbers
of rabbits needed in the captive breeding
population. To reduce the risk of disease
to the pygmy rabbit population at WSU, additional
breeding facilities are needed so that separate
populations of pygmy rabbits can be reared.
The Oregon Zoo, Northwest Trek near Tacoma,
and Zoo Mont. in Billings, Mont., have expressed
interest in maintaining Washington rabbits
at their facilities. Especially needed are
facilities close to arid environments because
of the rabbits' need for fresh sagebrush,
particularly during the winter. WSU is growing
sagebrush at its facility for this purpose.
- The
culmination of the breeding program - release
of the rabbits back into the wild– requires
careful preparation. Prior to release, captive
rearing specialists will attempt to train
young rabbits to avoid predators, using
procedures developed in earlier federal
captive rearing programs for the black-footed
ferret. Release sites will be selected in
suitable habitat. Reintroduction to the
wild will be achieved in gradual steps,
using tests of "soft" releases,
where rabbits will be protected from predators
with barriers such as electric fences for
a period of time before the animals are
released in to the wild. The rabbits will
be released near unoccupied, existing natural
burrows or provided with artificial burrows
for cover until they dig their own burrows.
A sample number of released rabbits will
be fitted with radio-transmitters and monitored
to determine their movements and survival
over time. Research will be conducted into
factors affecting the rabbits' survival
and reproduction in the wild, and rearing
and release procedures will be adapted accordingly.
Mortality is expected to be high among the
released rabbits, as it is in wild populations,
but the goal of the rearing effort is to
produce enough rabbits to compensate for
the loss.
 A
vital aspect of the recovery program is the
protection and acquisition of suitable habitat.
The prospect for pygmy rabbit habitat is favorable.
The Nature Conservancy, Bureau of Land Management,
and WDFW have been acquiring and protecting
both existing and potential pygmy rabbit habitat.
Meanwhile, Douglas County is developing a
Habitat Conservation Plan that may help provide
pygmy rabbit habitat. An increasing number
of landowners are enrolling in the federal
Conservation Reserve Program (CRP), which
pays farmers to allow some of their land to
return to wild conditions, and there is evidence
pygmy rabbits can make some use of lands in
CRP status. Finally, there is a concerted
effort among conservation groups and WDFW
to plan and implement pygmy rabbit habitat
acquisition to create a contiguous area, rather
than fragmented pieces.
Besides
the emergency recovery measures, WDFW also
is addressing other risk factors for pygmy
rabbits. Fire is one of the biggest risk factors
to pygmy rabbit habitat. One of the rabbit
populations that was lost was due to fire
at Coyote Canyon in 1999. WDFW Wildlife Area
Manager Mark Hallet and his assistant Dan
Peterson have developed fire plans for the
critical habitat at Sagebrush Flat, including
fire breaks, emergency response plans and
prevention measures. Small population sizes
increase potential impacts from predation
and disease. Cattle may pose risks to small
populations by drawing predators, trampling
burrows, competing for food and spreading
disease.
It
is estimated that the pygmy rabbit recovery
project will cost WDFW about $250,000 a year.
The Department's wildlife biologists initiated
the work with $115,000 from federal and state
funding, and have submitted proposals to the
Bonneville Power Administration (BPA) and
the U.S. Department of Interior to fund three
to five years of the project.
WDFW
is committed to preventing the loss of the
pygmy rabbit from the state's ecosystem. With
adequate funding and teamwork, we believe
we have a good chance of restoring this endangered
species to Washington's Columbia River Basin.
Related
Research
WDFW research into shrubsteppe habitat and its role in bird species abundance
is detailed in a paper published in 2000 in Conservation Biology (Volume
14, pages 1145-1160) by W. Matthew Vander Haegen, Frederick C. Dobler
and D. John Pierce, which may be viewed at: http://wdfw.wa.gov/wlm/research/papers/shrub
Related
Pygmy Rabbit Web Links
WDFW
1995 Pygmy Rabbit Recovery Plan and 2001 Washington
Pygmy Rabbit Emergency Action Plan for Species
Survival:
http://wdfw.wa.gov/wlm/diversty/soc/recovery/pygrabit/pygrabit.htm
US
Fish and Wildlife Service and Conservation
Groups Reach Agreement to List New Species
Under the Endangered Species Act:
http://midwest.fws.gov/ExternalAffairs/Release01-50a.html
Pygmy
rabbit References:
http://www.fs.fed.us/database/feis/animals/mammal/brid/references.html
Distribution
and Abundance of the Pygmy Rabbit, A C2 Species,
on the Idaho National Engineering Laboratory:
http://esrf.org/research/SUMMRPTS/PYGM_R.HTM
Other
captive breeding efforts
Vancouver
Island marmot recovery program:
http://www.marmots.org
California
Condor Recovery:
http://www.peregrinefund.org/conserv_cacondor.html
Black
footed ferret:
http://www.blackfootedferret.org
Author
Biography
 David
Hays is an endangered species specialist
with the WDFW Wildlife Program. He currently
coordinates recovery efforts for the pygmy
rabbit. David has worked as a conservation
biologist and endangered species biologist
with WDFW since 1989. He has been involved
in developing conservation strategies for
the marbled murrelet and spotted owl, among
other species. He served on the Science
Advisory Group for the DNR Habitat Conservation
Plan in Washington, on the Timber Advisory
Group for Gov. Booth Gardner, and served
as a scientific advisor to the Washington
Forest Practices Board for development of
spotted owl regulations on state and private
land. He was part of a team that developed
the Draft Recovery Plan for the Northern
Spotted Owl and the Conservation Strategy
for the Northern Spotted Owl. He has published
scientific papers on spotted owls and northern
goshawks, has written WDFW status reports
and recovery plans for sage grouse, sharp-tailed
grouse, western pond turtle, leopard frog,
and common loon, and has recently completed
a two-year research project on grassland
butterflies in western Washington. David
received a bachelor of science degree in
Wildlife Management from Washington State
University, and is a native of Washington
state.
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