Leeches suck. Most individuals attempt to keep away from them. But in the summertime of 2016, park rangers in China’s Ailaoshan Nature Reserve went looking for the little blood gluttons.
For months, the rangers searched via the reserve’s evergreen forest, gathering tens of 1000’s of leeches by hand and typically plucking the slimy parasites from the rangers’ personal pores and skin. Each time the rangers discovered a leech, they’d place it into slightly, preservative-filled tube, tuck the tube right into a hip pack and stick with it. The work might assist help conservation efforts, at Ailaoshan and elsewhere.
There are some ways to measure how a lot effort goes into wildlife conservation, but it surely’s tough to evaluate the success of that effort, even in protected areas, says Douglas Yu, an ecologist on the Kunming Institute of Zoology in China.
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But bloodthirsty worms could also be simply the software for the job. Leeches aren’t choosy eaters — they’ll feast on the blood of many various creatures, from amphibians to mammals to fish. Scientists have proven they will extract animal DNA from blood that leeches and different bloodsucking creatures have ingested, what’s often called invertebrate-derived DNA, or iDNA, and determine the supply animal.
And some researchers had instructed that iDNA, a sort of environmental DNA, may very well be used to hint the ranges of animals in an space, Yu says (SN: 1/18/22). “We thought we would just actually just try to do it.”
Enlisting 163 park rangers, Yu and colleagues deputized the leech-hunters with gathering the parasites alongside rangers’ common patrol routes, which lined all 172 areas of the reserve.
Three months later, the rangers had gathered 30,468 leeches. After extracting and analyzing animal DNA from the leeches’ blood meals, Yu and colleagues detected the presence of 86 completely different species, together with Asiatic black bears, home cattle, endangered Yunnan spiny frogs and, after all, people.
What’s extra, the iDNA gave clues to the place the animals most well-liked to roam, the researchers report March 23 in Nature Communications. Wildlife biodiversity was biggest within the reserve’s high-altitude inside, the researchers discovered, whereas home cattle, sheep and goats had been extra plentiful within the reserve’s decrease, extra accessible zones. Because a lot of the wild species detected ought to be capable to inhabit all elements of the reserve, the dichotomy means that human exercise could also be pushing wildlife away from sure areas, Yu says.
Compared with different strategies for surveying wildlife, utilizing iDNA from leeches is “really cost- and time-efficient and doesn’t require a lot of expertise,” says Arthur Kocher, an ecologist on the Max Planck Institute for the Science of Human History in Jena, Germany, who was not concerned within the research.
Camera traps, as an example, are triggered solely by animals of huge sufficient dimension, and the devices are costly. Sight-based surveys require educated observers. With leeches, Kocher says, “there are clear advantages.”
Yu and Kocher each suspect that leeches and different bloodsucking critters, corresponding to carrion flies or mosquitoes, will develop into extra common wildlife surveillance instruments sooner or later. People have gotten extra conscious of what iDNA brings to the desk, Yu says.