The US government is set to unleash drones that fire vaccine-covered M&M chocolates in a bid to save the endangered black-footed ferret, a species that is facing a plague epidemic across America's Great Plains.
The US Fish and Wildlife (FWS) has developed a plan to bombard ferret habitat in Montana with the vaccine, which will be administered via specially designed drones that will be able to shoot M&Ms in three directions simultaneously.
The vaccines will be targeted at the prairie dog population at the UL Bend National Wildlife Refuge in north-eastern Montana. Black footed ferrets – North America's only native ferret – are completely dependent upon prairie dogs, which are a type of burrowing rodent, for their food and shelter.
Both black-footed ferrets and prairie dogs are susceptible to the sylvatic plague, a flea-borne disease spread from rats that were introduced from ships arriving in California in the 1800s. While individual ferrets can be vaccinated by an injection, wildlife officials have found it difficult to protect prairie dogs over large areas.
Black-footed ferrets feast upon prairie dogs and invade their burrows, meaning that the disappearance of their co-dependent animal would prove disastrous for the species. Prairie dogs are considered a ''keystone'' species due to their importance to a range of animals, such as eagles, owls and coyotes.
''We dropped the vaccine out of a bag while walking around, but that's very hard to do over thousands of acres,'' said Randy Machett, a FWS biologist. ''Spraying burrows with insecticide to kill the fleas is also labour 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.''
Machett said a ''glorified gumball machine'' has been devised to dispense the vaccine. This device can be fitted to a drone, which will use its GPS to reliably drop vaccines at 30ft intervals. The drone will also be able to fire out the M&Ms to the left and right, meaning that three vaccines can be dropped at once.
A modified fish bait machine has helped create the vaccine, which will consist of M&Ms smeared in vaccine-laden peanut butter. Machett said lab tests show that prairie dogs find the bait ''delicious'', with a dye added to the mix reliably showing up on the animals' whiskers.
Only 300 black-footed ferrets remain in the US across a handful of isolated sites. The species was briefly thought to be extinct in 1981, only for a number of animals to be brought into captivity for breeding. The current population originates from just seven ferrets that were selectively bred.
Black-footed ferrets and prairie dogs have suffered population crashes due to disease, shooting and habitat loss. Many farmers still consider both species to be a pest, with some voicing their unhappiness at the M&M drone plan.
However, Machett said most submissions during a public comment period were ''highly supportive'' of the plan and he hopes that it will be operational by 1 September following final FWS approval. Other ferret populations in Arizona and Colorado will also be aided by the drones following the trial in Montana.
''It is the fastest, cheapest way to distribute the vaccine,'' Machett said. ''We are hopeful this oral vaccine will be used to mitigate plague sites and treat tens of thousands of acres each year.
''This is what the Endangered Species Act is all about – saving species, particularly those affected by human actions.''