The U.S. launched espionage satellites during the Cold War to locate Soviet missile sites, but in doing so, they also captured photos of animals and their historic habitats, Science magazine reported.
Now, scientists have put these 1960s snapshots to new use: showing how a specific population of marmots in Kazakhstan has dwindled over the last five decades.
The same approach could be used to study how other animal populations have changed through time, particularly in regions with little historic data on record, the authors wrote in a report published May 19 in the journal Proceedings of the Royal Society B.
For each sample plot analyzed in the study (each 0.6 miles (1 kilometer) in diameter), the authors derived the number and location of all burrows for a historic and a contemporary time period. An image from 1969 can be seen on the left, and an image from 2012 on the right.
Using a U.S. Geological Survey database, the team collected black-and-white images captured by Cold War-era satellites launched as part of a U.S. espionage program called Corona. Poring over images of the grasslands of northern Kazakhstan, they searched for evidence of bobak marmots (Marmota bobak) — large prairie dog-like rodents that live in underground burrows, which they can use for many decades. The team identified more than 5,000 marmot burrows in the historic photos and estimated that, since the 1960s, about eight generations of marmots have occupied some of those very same burrows.
However, far fewer bobak marmot burrows exist today than did 50 years ago. The number of burrows declined by about 14% across the entire region, and by as much as 60% in grasslands that had been converted into wheat fields, the study found.
Marmots often return to rebuild burrows disrupted by farming, but in heavily cultivated areas, the energetic cost of reconstructing burrows over and over again may prove too great, the authors wrote. This may explain why marmot populations fell steeply in the oldest wheat fields included in the study, as those were subject to persistent plowing over many years, they wrote.
The work may be the longest record of how mammals respond to their habitat being developed for agriculture, study author Catalina Munteanu, a geographer at Humboldt University of Berlin, told Science magazine.
Using historic satellite images and other archived data could help humans better manage activities to reduce our impact on animal habitats, Daniel Blumstein, an ecologist and marmot expert at University of California, Los Angeles, who was not involved in the study, told Science.
Bobak marmot
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Originally published on Live Science.
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