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Tracking the elusive Burmese python—with DNA clues in the dirt

When a Burmese python slithers out of its burrow, it leaves part of itself behind. Now, for the first time, scientists have used that part—DNA traces in the soil—to track the elusive snake in southern Florida.

First, they wanted to see whether it was even possible to pick up such traces, which most animals release whenever they expel waste or shed skin. Past studies have looked at waterborne DNA to identify snakes, fish, and other aquatic animals, but few have looked at soil-based DNA. Back in the lab, the researchers placed three red corn snakes in soil-lined containers for a week and found that their DNA gradually built up in the dirt below, disappearing 4 to 7 days after they were taken out of their containers.

Armed with that information, the researchers ventured into a reserve on Florida’s gulf coast to gather soil from the burrows of Burmese pythons, an invasive species that has wreaked havoc there by devouring any animal it can fit into its massive jaws. All 43 burrows in the study were monitored by cameras or other sensors. In two of the three burrows with video evidence of recent visitors, researchers found python DNA; none was present in any of the other burrows. By simply sampling the dirt, the researchers discovered whether and when a snake had been in a particular spot, they report this month in Herpetologica. The new technique, they say, could help conservationists and land managers protect Florida’s native animals by revealing where the pythons are hiding—and where they are spreading.