The United States launched early spy satellites in response to the Soviet Union Sputnik (first artificial satellite, 1957) and other space efforts. The espionage program, titled Corona, was aimed at locating Soviet missile sites, but its orbital photography captured something unintended: snapshots of animals and their habitats frozen in time. Now, by comparing these images with modern data, scientists have found a way to track the decline of biodiversity in regions that lack historic records.
The researchers tested the approach on bobak marmot (Marmota bobak) populations in the grassland region of northern Kazakhstan. There, Soviets converted millions of hectares of natural habitat into cropland in the 1960s. The scientists searched the satellites' black and white film images on a U.S. Geological Survey database for signs of the squirrel-like animal's burrows.
They identified more than 5,000 historic marmot homes and compared them with contemporary digital images of the region, mapping more than 12,000 marmot burrows in all. About eight generations of marmots occupied the same burrows in the study area over more than 50 years, even when their habitats underwent major changes, the team reports in the Proceedings of the Royal Society B. Overall, the researchers estimate the number of marmot burrows dropped by 14% since the '60s. But the number of burrows in some of the oldest fields -- those persistently disturbed by humans plowing grassland to plant wheat -- plunged by much more -- about 60%.
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