A slightly unconventional method is being employed to vaccinate prairie dogs in north-eastern Montana. The US Fish and Wildlife Service is set to send out a drone that fires out vaccine-laden M&M’s in the hope that it will help reduce the level of plague found in UL Bend National Wildlife Refuge, and protect the endangered black-footed ferrets that call the park their home.

The vaccines are not actually aimed at targeting the ferrets themselves, but instead are intended for the prairie dogs that share their habitat and form the main part of their prey base. The rodents are highly susceptible to the plague, which is carried by the fleas that live on them. The ferrets depend on the prairie dogs not only for food, but also for the burrows they dig in the grasslands, and this puts them into direct contact with the diseases they carry.

With no more than a thousand black-footed ferrets (Mustela nigripes) surviving in the wild – after being reduced to a population thought to have been as small as nine individuals in the 1980s – and spread across a few different sites, the survival of the creature is still balancing on the brink. Persecuted by farmers and a victim of the poison laid down for prairie dogs, they are also highly susceptible to both the human-introduced and naturally occurring diseases, such as the plague.

^{A young ferret learning to hunt its main prey, a prairie dog. USFWS Mountain-Prairie/Flickr CC BY 2.0}

The baits are made by smearing M&M’s with peanut butter laced with a vaccine that protects against the plague. The biologists have also added a dye to the mix that stains the rodent’s whiskers, so they know exactly which of the squat little mammals have been snacking on the tasty treats. The slightly eccentric choice in bait was actually arrived upon through lab tests, which showed that the prairie dogs found the peanut butter coated M&M’s “delicious”.  

Previously, conservationists have tried to reduce the prevalence of the plague in the park by spraying the burrow entrances with insecticide, which is only a short term solution, and manually wandering around dishing out the M&M’s, but this was only met with limited success and required a lot of work, plus they had no way of preventing any singular prairie dog with a particular penchant for M&M’s from monopolizing them. Anyway, why do something yourself, when you can simply employ a drone to fly around spitting out the delicious vaccine candies for you?

The drone will fly across the refuge firing M&M’s in three directions at 9-meter (30-foot) intervals, and will enable the biologists to distribute the vaccine evenly. The plan is to have it in the air by September, and if successful, introduce the drones to other parks that need protecting.

^{Main image: USFWS Mountain-Prairie/Flickr CC BY 2.0}