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Tracking Wildlife With Nothing But Blood-Filled Flies

Why bother with the long, hard work in the wilderness looking for rare animals when you can just trap some flies, pump their stomachs, and get a genetic picture of what animals they’ve been feeding on?

Tracking Wildlife With Nothing But Blood-Filled Flies
Flies via Shutterstock

If you’re searching for Jentink’s duiker, the critically endangered antelope species in Africa, good luck. Only 3,500 individuals are believed to survive in the wild. You might as well find a unicorn. But a Jentink’s duiker is exactly what researchers from the Max Planck Institute for Evolutionary Anthropology in Germany found last year, along with dozens of other species, using a new field technique to survey mammals in the wild: flesh-eating flies.

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Inspired by the way leeches carry around genomic evidence of their past meals, the researchers trekked to Cote d’Ivoire and Madagascar to catch and pulverize 201 carrion flies to extract any mammalian DNA lurking in their bodies. By decoding the DNA from bugs’ last bloody meals, they found 22 species in Cote d’Ivoire and four in Madagascar across a spectrum of ecological niches. The flies yielded a cheap, lightening quick snapshot of local mammal diversity. Mammal species identified including African palm civet, shrews, mangabey monkeys, chimpanzees and a signficant share of the local primate diversity. The researchers, publishing in the journal Molecular Ecology, say carrion flies “represent an extraordinary and thus far unexploited resource of mammal DNA.”

It’s easy to understand why field researchers are so excited. Flies that feed on carcasses, feces and open wounds of animals in remote ecosystems are much easier to catch–set out some rotting meat, and throw a net over them–than the laborious tracking or capture methods used today. Surveying a region’s mammal population is also critical to protecting them, so the tool can become a first line of defense for wildlife conservation in poorly understood areas.

And the German scientists are not alone. A group of researchers in Africa, publishing in the open access journal PLOS One, ran a similar study on the guts of tsetse flies in the Serengeti ecosystem. Their genetic menageries included buffaloes, giraffes, warthogs, elephants and one spotted hyena.

Big game hunting was never quite so easy.

About the author

Michael is a science journalist and co-founder of Publet: a platform to build digital publications that work on every device with analytics that drive the bottom line. He writes for FastCompany, The Economist, Foreign Policy and others on science, economics, and the environment.

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