Using Leeches to Track the World's Rarest Animals

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The Grizzly Bear, the Snow Leopard, the Orangutan—these animals were once thought to be mere folklore before their existences were proven with hard, biological evidence. Now, one research team wants to harvest the same evidence from the world's wilds using a natural collection network of leeches.

Monitoring wildlife is both an essential aspect of any conservation effort and one of its most difficult challenges. Getting researchers, equipment, and monitoring tools into the field for a sufficient length of time and back is a logistical nightmare. And it's only made more difficult when the wildlife being surveyed is exceedingly rare or shy—or both, as in the case of the Snow Leopard. "The problem is particularly acute in tropical forests, where a disproportionate number of species are listed by IUCN as ‘data deficient', due to the difficulty of monitoring with conventional approaches. This presents serious obstacles to conservation management," states the report's summary.

So instead of combing the forest floor for long-since-decomposed biological samples, or relying on remote camera networks, one research team has discovered a new way of collecting blood samples of these reclusive animals—they pull it from the guts of leeches.


The team from University of Copenhagen in Denmark, in collaboration with researchers from Cambridge University and Copenhagen Zoo, discovered that blood can last in the gut of a leech for up to four months. By extracting that blood, a la Jurassic Park, they can sequence it and see exactly what the leech was feeding on. So, instead of having to send researchers out to find the animals themselves, they can simply pick up a few leeches and sample the fauna indirectly.

On a recent test expedition, the team, led by Tom Gilbert of the University of Copenhagen, collected 25 leech "samples" from a remote forest in Vietnam. Upon sequencing the collection, the team found four leeches contained the DNA from a striped rabbit only rumored to inhabit the area (this was the first confirmation), one leech contained the DNA of a Muntjac, six more had dined upon a rare badger and three more had recently had a rare species of goat. So, all in all, a pretty successful expedition.


Now granted, this method certainly isn't going to replace traditional field work—animals aren't going to radio-collar themselves—but who knows, this could be how we obtain the first real, hard evidence of Bigfoot. Beats waiting for somebody to finally shoot one. [Current Biology via New Scientist - Image: sydeen / Shutterstock]