[You must be registered and logged in to see this image.]In 1980, the black-footed ferret was declared “possibly extinct”. But, almost miraculously, it has returned from the dead. Gerardo Ceballos Gonzalez explains how luck and hard work have saved the little carnivore of the prairie.
The black-footed ferret is a small carnivore, similar in length to a domestic cat. Its short legs and long, slim body make it superbly adapted for life in the burrow systems of prairie dogs, which are almost its sole prey. It spends most of its life underground – remaining in each burrow for up to 10 days at a time – only emerging to seek a mate or another burrow to plunder. Prairie dogs do not wait to be hunted down by the ferrets. They often plug their burrow entrances with soil from the inside, but a determined ferret will dig through using its powerful forepaws.
The black-footed ferret’s limited diet means its fate is inexorably linked to that of the prairie dog, which was once one of the most abundant mammals in the American West. Up to the 19th century, it lived in vast colonies that extended almost uninterrupted from southern Canada to northern Mexico. But as ranching and agriculture expanded, the prairie dog became a target for extermination.
In the early 1900s, the US Government even put a bounty on its head. The prairie dog was eradicated from 98% of its original range. Even today, it is still trapped and poisoned, because ranchers believe that this tiny rodent competes with livestock for grass – a belief that belies recent research showing that prairie dogs and cattle feed on different plants.
The eradication of the prairie dog led directly to the decline of the black-footed ferret. The first efforts to conserve the species began in 1974, when the remaining wild individuals were brought into a captive-breeding programme. Sadly, they did not fare well, and in January 1979 the last of them died – making the black-footed ferret the first mammal to become extinct in the northern hemisphere in the 20th century.
Back from the dead
But you can’t keep a good ferret down. Two years later, a Labrador carried an odd-looking creature to its owner’s ranch in Meeteesee, Wyoming. Luckily, instead of throwing it out, the rancher put the carcass in his fridge and alerted state officials. The dog had found a black-footed ferret – thus effectively saving the species from extinction. An intensive search in the region led to the discovery of a 100-strong population.
The colony thrived for a while, but disaster struck again and the animals were decimated by distemper – probably contracted from domestic dogs. In a final bid to save the species, the remaining 18 wild ferrets were trapped for a new captive-breeding programme. This project was successful, and there are now more than 2,000 ferrets in captivity across the US and Canada.
The future of the black-footed ferret now depends on finding enough places to support viable wild populations – and there is one location that is key. The Janos area on the US-Mexico border is one of the most important remnant grassland ecosystems in the Americas. The landscape seems vast, but it is a mere fraction of what the US-Mexico Boundary Commission found when its representatives established the border in 1893.
Major Edgar A Mearns, naturalist for the US party, found abundant deer, antelope, bighorn sheep, brown and black bears, wolves and pumas. But he was most surprised by the prairie dogs, writing: “For miles, the burrows of these animals are scattered over the plains… As we rode amongst them their sharp barking was incessant and their tameness surprising.” Today, the wolves and grizzlies have gone, but prairie dogs still dominate. This was the obvious place to reintroduce black-footed ferrets.
Survival techniques
Before captive ferrets can be released into the wild, they have to be taught how to hunt. They are first released into holding pens on the prairie, to keep them safe from predators until they learn to avoid them. To teach the ferrets to hunt, we feed them dead prairie dogs. Once they associate these animals with food, we release live prey into the pens. The ferrets soon realise that they must hunt or go hungry.
Teaching them to live underground and avoid predators is more complicated, since captive-born ferrets are not used to using burrows as refuges. We have to lure them into the holes with bait as a response to danger, a time-consuming but vital process.
Since 2001, we have released more than 200 ferrets and, in 2002, we spotted our first wild-born kit. We calculate that there are now about 25 wild-born ferrets in Mexico – a quarter of the total wild population. We hope to release more animals in 2008 and 2009. But we have to act fast to reduce the impact of human activities in the region.
When we first discovered the Janos prairie dog colony in 1987, it covered 55,000 hectares. It has since shrunk by almost 50 per cent, due to encroaching agriculture and mesquite scrubland. A major drought is exacerbating the problem.
We are working towards formal protection of the land, improved cattle management and restoration of the prairie dog colonies. My dream is that we will be able to enjoy and learn about these and other prairie species for many years to come.
Wed Sep 05, 2012 8:37 am
