Download scientists to use satellites to count kangaroo rats

Scientists To Use Satellites to Count Kangaroo Rats
By Tracie Cone, Associated Press r
September 18, 2008
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A giant kangaroo rat is seen in this undated photo provided by the Nature Conservancy.
When the San Joaquin Valley was an arid grassy plain, giant kangaroo rats were the
seed-hording gardeners that helped propagate native plants. Now scientists are turning
to satellite technology to determine how climate change and rainfall patterns are
affecting the endangered species' remaining habitat. Photos. (AP Photo/University of
California, Berkeley, John Roser)
FRESNO, Calif. - Scientists plan to use satellite photos to count Giant Kangaroo Rats,
the first-ever monitoring of an endangered species from outer space.
Scientists will examine images taken from the same satellite used by Israeli defense
forces to find the circular patches of earth denuded by the rats as they gather food
around their burrows. From that they plan to get the first-ever accurate population count
of the rodents, a bellwether for the health of a parched plains environment.
By comparing the photos to 30 years of satellite images being released this month by
the U.S. Geological Survey, researchers hope to better understand how the population
has fluctuated in response to climate change and as the arrival of state and federal canal
water turned the arid San Joaquin Valley into a patchwork of intensely cultivated farms
and forced Giant Kangaroo Rats to concentrate on higher ground.
The information will help scientists determine when cattle might be used to reduce
nonnative grasses, allowing the rats to more easily find food.
This study using satellite technology is taking place on the vast Carrizo Plain, a 390square-mile desert grassland 150 miles southwest of here that is home to the most
concentrated remaining populations of kangaroo rats.
The technology replaces trapping and tedious airplane fly-overs as a means of taking
census.
"It allows us to more quickly recognize whether populations are declining where we want
them to exist," said Scott Butterfield, a biologist with of The Nature Conservancy. "If they
go below a threshold, that is when we would consider intervening."
Giant Kangaroo Rats, nocturnal rodents so named because they hop on back legs,
adapted to their desert environment by extracting moisture from seeds and in their nasal
passages from the humid air they exhale. For food, they pile seeds from native grasses
in circles outside their burrows, which provide shelter for the endangered San Joaquin
antelope squirrel and blunt-nosed lizards. Their fat five-inch bodies are a favored source
of food for the endangered kit fox.
High rainfall encourages the growth of taller nonnative grasses, which overrun the
shorter grasses that kangaroo rats depend on for food. Less food means fewer offspring.
When kangaroo rats decline, so do the endangered native plant and animal species that
depend on them for survival, the researchers say.
Determining at what point rainfall affects foraging will help the U.S. Bureau of Land
Management establish grazing policy to control nonnative grasses and encourage a
healthy kangaroo rat population.
"Without them the entire ecosystem would go out of whack," said Tim Bean, a doctoral
student with the department of environmental policy and management at the University
of California, Berkeley. "It's fairly rare for something so small to be a keystone species.
It's easier to track, say, bison."
Farming has taken 90 percent of the kangaroo rat habitat since the middle of the last
century.
The Carrizo Plain National Monument is California's largest remaining undisturbed tract
of grasslands similar in biology and geography to the San Joaquin Valley, and it
supports many plant and animal species that once thrived on the valley floor.
"Carrizo is like a Yosemite for grasslands, and there are decisions people are learning to
make to manage it in a way that preserves its natural state," Bean said. "Since the
kangaroo rat is so important to its function, we've got to get a handle on it."
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On the Net:
Carrizo Plain National Monument:
http://www.blm.gov/ca/st/en/fo/bakersfield/Programs/carrizo.html
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