As they swim, slither, and otherwise move through their environments, animals leave bits of their DNA behind. As Carl Zimmer writes at the New York Times, researchers are using these bits of leftover DNA to track otherwise hard-to-find animals.
Stephen Spear from the Orianne Society turned to such environmental DNA testing to count the number of hellbenders, rather shy salamanders that live under rocks, instead of the usual approach of overturning rocks and catching what flees from beneath them.
"Essentially, everywhere that we know that they're there from past surveys, we'd pick them up," Spear tells Zimmer. And they haven't found hellbender DNA in regions outside of their known range.
This approach, Zimmer says, not only comes in handy for counting the number of hellbenders and spawning salmon, but also to get a handle on invasive species like the Burmese pythons of the Florida wetlands
Still, the University of Copenhagen's Eske Willerslev notes that more research into how long DNA can persist in the environment needs to be conducted, though Zimmer says Willerslev is optimistic that studies of environmental DNA can give insight into species diversity and population size in certain ecosystems.