September 19, 2008
Scientists Use Satellites to Track Endangered Species
For the first time ever, scientists will use satellites in space to monitor the fluctuations of endangered species populations.
The scientists will use satellite photos to count and monitor giant kangaroo rats, a key indicator for the health of a dry plains environment. The photos will be obtained from the same satellites the Israeli defense forces use, and will be compared with 30 years of satellite images released this month by the U.S. Geological Survey.
Researchers aim to use this data to determine the impact of climate change and other conditions, such as the transformation of California's once-arid San Joaquin Valley into a mosaic of highly cultivated farms, which have forced the giant kangaroo rats to higher ground. Farming has robbed the rats of 90 percent of their habitat since the middle of last century.
The information obtained from the satellites will also help scientists assess when cattle could be used to reduce nonnative grasses, something that would make it easier for the rodents to find food.
The research is being conducted on the large Carrizo Plain, a 390-square-mile desert region 150 miles southwest of Fresno and home to the most concentrated remaining populations of kangaroo rats. The Carrizo Plain National Monument is California's largest unmolested tract of grasslands, and is similar in biology and geography to the San Joaquin Valley. It supports many animal and plant species that once thrived in the area.
"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," Tim Bean, a University of California doctoral student with the department of environmental policy and management, told the AP.
"Since the kangaroo rat is so important to its function, we've got to get a handle on it."
The use of satellite technology replaces trapping and dreary airplane flyovers as a way of obtaining population counts.
"It allows us to more quickly recognize whether populations are declining where we want them to exist," Scott Butterfield, a biologist with of The Nature Conservancy, told the Associated Press.
"If they go below a threshold, that is when we would consider intervening."
Giant kangaroo rats are nocturnal rodents named for their ability to hop on their back legs. Their plump, five-inch bodies are a favored food source of the endangered kit fox. They adapted to their desert environment by removing moisture from seeds and from within their nasal passages from the humid air they exhale.
The rats gather seeds from native grasses in circles outside their burrows to obtain food. These burrows also serve as shelter for the endangered San Joaquin antelope squirrel and blunt-nosed lizards.
Increasing rainfall promotes the growth of taller nonnative grasses, which can often overrun the shorter grasses that kangaroo rats use for food. Less food results in fewer offspring and a declining population. When this happens, the endangered native plant and animal species that depend on the rats for survival also decline, according to researchers.
Determining the precise point at which falling rainfall affects foraging will help the U.S. Bureau of Land Management (BLM) set an appropriate grazing policy to control nonnative grasses and restore the kangaroo rat population.
"Without them the entire ecosystem would go out of whack," Bean said.
"It's fairly rare for something so small to be a keystone species. It's easier to track, say, bison."