It sounds like a sci-fi story, with drones dropping candies coated with plague vaccine in order to save an endangered species and its food source.

How do you vaccinate a large number of wild animals against a deadly disease? With robotic candy dispensers, of course.

The black footed ferret, which has been on the endangered species list for decades, could be facing extinction, with only several hundred individuals still living in the wild. According to the US Fish and Wildlife Service (FWS), this ferret is “one of North America’s rarest mammals.” And one of the factors that may lead to their demise is a bacterial plague – the sylvatic plague, to be exact – which is transmitted by fleas, and for which there is a vaccine.

Aside from preying on prairie dogs, the black footed ferret also co-opt their burrows for their own, so treating prairie dog burrows with a ‘pulicide’ (a flea-killing agent) that can help break the chain of plague transmission has been one of the ways that wildlife agencies have addressed the issue. However, it’s suspected that these fleas are developing a resistance to this kind of chemical control, which means that other methods are called for, such as the vaccine.

The problem is finding ways to get the vaccine into their bodies, and into those of prairie dogs, in order to stave off a collapse of this ferret food source and habitat provider. And while hand-dispensing an oral sylvatic plague vaccine (SPV) can be somewhat effective, it’s also limited by the sheer size of prairie dog and black footed ferret habitats, which can stretch for thousands upon thousands of acres. Which is where drones, or unmanned aerial systems (UAS) come in, as they could be tasked with precisely delivering vaccine-laced baits (in this case M&Ms coated with a peanut butter/vaccine mixture) across large areas.

According to the US FWS, delivery of the vaccine using drones “is potentially the most efficient, effective, cost-conscious and environmentally friendly method of application,” and could radically increase the vaccine delivery rates from the current manual method of 3 to 6 acres per hour to an ‘automated’ rate of 60 to 200 acres per hour. In The Guardian, Randy Machett, a FWS biologist, relates that a “glorified gumball machine” attached to GPS-guided drones could deliver the vaccine baits reliably – three at a time – at precise intervals across critical habitat.

“We dropped the vaccine out of a bag while walking around, but that’s very hard to do over thousands of acres. Spraying burrows with insecticide to kill the fleas is also labor intensive and not a long-term solution. So we are working with private contractors to develop equipment to drop the vaccine uniformly across an area, rather than one hog getting to eat a big pile of them.” – Randy Machett

The US FWS has completed its impact assessment and the public comment period has closed, so the agency could see this drone-enabled vaccine delivery system begin operations in September, assuming a final approval is granted.

Image: USFWS