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Date:    Wed, 5 May 1999 02:26:06 EDT
From:    C 
Subject: Cornell News - Why squirrels need fire

----------------------------Original message----------------------------

     One of continent's rarest animals is disappearing because
     of suppression of natural fires, Cornell genetics study
     suggests

May 3, 1999

Contact: Roger Segelken
Office: (607) 255-9736
E-Mail: hrs2@cornell.edu


     Cornell biologist Thomas Gavin indicates encroaching
     vegetation that isolates Northern Idaho ground squirrels
     to small patches of habitat. Photo courtesy of Paul
     Sherman
               ITHACA, N.Y. -- Cornell


University biologists who study dwindling populations of one of
the rarest mammals in North America have found another reason to
let "natural" fires burn. Without lightning-sparked fires every
10 to 12 years, they say, pine trees are isolating Northern Idaho
ground squirrels into shrinking groups where non-native plants
that do not supply adequate food for the rodents have overwhelmed
natural, fire-resistant, seed-laden grasses.

"Animals can run from fire, but they can't escape the disastrous
effects of habitat fragmentation and starvation. Unless these
squirrels can link up with neighboring populations and obtain
sufficient fatty seeds to carry them
through hibernation, I'm afraid they will die off altogether in
our lifetime," says Paul Sherman, one of four biologists
authoring a genetic study of the Northern Idaho ground squirrel
( Spermophilus brunneus brunneus ) in the current Journal of
Mammalogy (Vol. 80, No. 1, pp 156-168).

Sherman, a Cornell professor of neurobiology and behavior, and
colleagues Thomas Gavin, Eric Yensen and Bernie May offer a
two-part solution for the squirrels' dilemma:

--  Restoration of habitat, including reopening of meadows, to
    reconnect squirrel populations.

--  Reintroduction of fire into the ecosystem to restore native
    vegetational structure.

Fourteen years ago, when Yensen of Albertson College of Idaho
began the squirrel study in the high-desert meadows of western
Idaho, there were about 1,000 of the ground squirrels on public
and private lands around Payette National Forest, the only part
of North America where the rare animals live. By 1998, the total
population had shrunk to about 600, and 12 of the 36 known
populations were extinct, according to Gavin of Cornell's
Department of Natural Resources.

The U.S. Fish and Wildlife Service has proposed listing S. b.
brunneus as "threatened," deserving of protection through the
Endangered Species Act.

The Northern Idaho ground squirrel depends on the fat-rich seeds
of native bunch grass to sustain it through seven or eight months
of hibernation. Before the federal government instituted a policy
of suppressing wildfires early in the century, the meadows burned
every 10-12 years, and the heat-resistant bunch-grass seeds then
regreened Idaho's meadows.

A rodent in cattle country, this Northern Idaho ground squirrel
is is marked by researchers with hair dye that wears off in a
month. The extremely rare squirrel is slightly larger than the
more familiar chipmunk. Photo courtesy of Paul Sherman.

But without natural fires to maintain the diversity of plant
life, Gavin explains, a few non-native plant species took over.
"The non-native plants put all their energy into rapid vegetative
growth rather than making nutritious seeds," he says. "As a
result, the ground squirrels cannot find enough seeds to fatten
sufficiently before their long hibernation, from August to
March."

Gavin adds, "To make matters worse, when squirrels try to migrate
in search of food or mates, their paths are blocked by dense
stands of pine trees that thrive in the absence of fire. This
means that groups can no longer mix when some populations expand
and others drop because of disease, a hard winter or predators.
Sometimes one hard winter and a little bad luck with hawks,
badgers and other predators are all it takes to wipe out an
isolated, local population. They cannot be rescued by dispersers
from nearby populations that are doing well."

Cornell's long-term study of Idaho ground squirrels had, at
first, focused on the animals' social behavior. But the focus
changed as researchers returned each spring to sites where small
colonies had thrived the year before -- only to find no animals
emerging from their winter burrows. Analysis of blood proteins
and DNA from surviving squirrels offered three clues:

--  Ground squirrels in isolated populations are slightly
    differentiated in their genetic makeup, suggesting that they
    probably intermingled earlier in the century, before dense
    conifer forests closed in, but that intermixing no longer
    occurs.

--  Squirrel populations as close as two miles apart are no
    longer mixing.

--             The farther apart populations are geographically, the more
    different they are genetically, suggesting that they have
    been separated longer, and that little or no dispersal is
    occurring between populations today.

The biologists' hypothesis -- that inadequate nutrition is one
cause for the squirrels' disappearance -- received a boost from
an "accidental experiment," when cattleman Frank Anderson moved
to a remote house on the OX Ranch. Within a year, the Idaho
ground squirrels around Anderson's residence were reproducing
like rabbits and doubling their weight during the summer months,
just like hibernating animals are supposed to.

Sherman and Gavin quickly pinpointed the cause of the population
explosion: Seed-starved squirrels were eating kibble the rancher
left outdoors for his herding dogs, as well as spilled oats from
horse feed.

Now the dog chow-fed squirrels are part of a deliberate
experiment by the Idaho Department of Fish and Game, the U.S.
Forest Service and researchers from Cornell and Albertson
College:

--  Controlled, "cool" fires are set to burn off non-native
    vegetation and underbrush that blocks the ground squirrels'
    movement from one population patch to others. Unlike hot,
    uncontrolled wildfires, the controlled burns should not
    destroy seeds of native plants, including some that require
    heat to germinate.

--  Burned meadows are reseeded to reintroduce native plants that
    the ground squirrels and other wildlife need.

--  Healthy squirrels from the ranch house population are
    humanely trapped and moved to prepared sites in burned and
    reseeded meadows. The biologists even dig burrows with power
    augers, giving the squirrels a head start in establishing new
    homes.

"It's not Purina dog chow, but they're finally getting plenty of
the leaves and fat-rich seeds of native grasses that they've been
missing," said Gavin. He credits students in the conservation
biology course he teaches at Cornell for highlighting the role
of nutrition in squirrel population problem.

Gavin said that controlled "cool" fires are not a threat to
ground squirrels, which are safely hibernating several feet
underground when controlled fires are set.

"We know this runs counter to everything Smoky the Bear taught
us," Sherman said. "But we think Smoky was worried about careless
campers and cigarettes, not the natural fires that are set by
lightning. Ironically, we've become so good at fire suppression
that many forests are tinder boxes of underbrush and non-native
vegetation. Now, when a fire gets out of control it really is a
threat to wildlife.

"The Idaho ground squirrels are part of an ecosystem that
functioned successfully for tens of thousands of years, and
natural fires were a part of that system, too," Sherman said.
"Perhaps by undoing some of mankind's tampering -- as
well-meaning as it was -- and setting back the clock, we can
encourage the re-establishment of native flora and fauna,
especially the rodent variety, while saving the immense costs of
fighting catastrophic fires every summer."

Authors of the Journal of Mammalogy report, "Population Genetic
Structure of the Northern Idaho Ground Squirrel," are Gavin,
Sherman, Yensen and May, formerly a research associate in
Cornell's Department of Natural Resources and now a researcher
in the Department of Animal Science at University of California
at Davis. The genetics study was supported, in part, by the
National Science Foundation, U.S. Department of Agriculture,
National
Geographic Society, Idaho Department of Fish and Game and the OX
Ranch.

Related World Wide Web sites: The following sites provide
additional information on this news release. Some might not be
part of the Cornell University community, and Cornell has no
control over their content or availability.

-- Idaho Department of Fish and Game:
http://www2.state.id.us/fishgame/fishgame.htmlct/life/ento/simon/9-idx.html

-- U.S. Fish and Wildlife Service - endangered species
information: http://www.fws.gov/r9endspp/endspp.htmlme.htmlct/life/ento/simon/9-idx.html

-- OX Ranch: http://www.sevendevils.com/cattle.htmllme.htmlct/life/ento/simon/9-idx.html

-- Cornell Department of Natural Resources:
http://www.dnr.cornell.edu/cattle.htmllme.htmlct/life/ento/simon/9-idx.html

-- Cornell Section of Neurobiology and Behavior:
http://www.bio.cornell.edu/neurobio/sofneurobio.htmle/ento/simon/9-idx.html

-30-

URL: http://www.news.cornell.edu/releases/May99/squirrel.fire.hrs.web.htmlx.html