Satellites Enlisted in Search for New Species

John Roach
for National Geographic News
September 13, 2005
Conservation biologists have recruited sophisticated satellites to help discover and protect unknown species before they disappear.

Sensors on the satellites can collect information such as the vegetation, climate, and topography of remote and unexplored regions, explained Christopher Raxworthy, the associate curator of herpetology at the American Museum of Natural History in New York.

In computer models these data are combined with information on habitats in which certain species thrive. The combination allows scientists to predict regions where species—some known, others not—are most likely to be found.

These data are combined with the coordinates of sites where a species is known to occur. Then, using computer programs, scientists analyze the information to predict other areas where the species might live.

Field scientists can then travel to the targeted area and search for the species. The technique helps eliminate some of the guesswork traditionally involved in conservation biology, speeding the pace of discovery and protection.

"Habitat loss in many regions is occurring so fast that some species may be lost before we find them," Raxworthy wrote in an e-mail to National Geographic News.

Madagascar Test

Raxworthy and his colleagues are using satellite data to help predict the locations of chameleons, lemurs, and other species on the island nation of Madagascar, located off the east coast of Africa.

"This next rainy season we will be testing these predictions," Raxworthy said. (The rainy season in Madagascar runs from November through April.)

This type of testing—called ground truthing—involves visiting regions that the computer models predict are homes to certain species and verifying the species' presence the old-fashioned way.

Ground truthing is essential to validating the satellite data, according to Woody Turner, a scientist with NASA's Science Mission Directorate in Washington, D.C.

"I believe it was Mark Twain who said there are three kinds of lies: lies, damned lies, and statistics," Turner said. "To that, I'd perhaps add a fourth: remote-sensing observations that have not been adequately ground-truthed."

Turner explained that satellite imagery beamed to Earth is easy to misinterpret. Only through ground truthing can scientists be confident that the computer models' predictions are true.

Once scientists have ground-truthed the imagery, they can apply their findings to unexplored regions with confidence.

Using satellite data, scientists can analyze larger areas "in ways you couldn't with information gained on foot or by driving a car," Turner said. "It allows you to make connections across large areas."

If Raxworthy and his colleagues' Madagascar ground-truthing test bears out their computer predictions, the team will use their results to help the island nation identify areas for conservation.

Madagascar is considered a biodiversity hot spot, an area that is home to great numbers of species and that is under constant assault from human activity.

In 2003 the country committed to tripling its protected area from 4.2 million to 14.8 million acres (1.7 million to 6 million hectares) by 2008.

Evolving Tool

According to Turner, the use of satellite technology in conservation biology is becoming more and more mainstream. "A number of things have happened coincidentally to push this," he said.

For one thing, satellite imagery is now widely available from government agencies and businesses. For another, the imagery is cheaper, making it more accessible to scientists with limited budgets.

Also, scientists can now take GPS (global positioning system) receivers out into the field to record the precise locations of where they make observations.

These data collections are then presented through GIS (geographic information system) technology, which has grown exponentially in recent years.

GIS technology incorporates the satellite and GPS data into interactive maps that scientists can view different ways, depending on what data are of the most interest.

Finally, the computer power and software required to process the information is vastly improved. "All of this has come together and made remote sensing effectively another tool that a lot of conservation biologists ... can use," Turner said.

Nonetheless, challenges remain.

The current challenge, Raxworthy said, is the lack of specialists trained to handle the satellite data and incorporate it into their work. "It takes a lot of time and money to train specialists, and currently there are not enough resources to accelerate training," he said.

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