By Alice Vincent, Wired UK
Rare pygmy rabbits are being reintroduced to their native Columbia Basin in the United States, bringing them back from the brink of extinction. It will be the first time that the endangered species has been seen in the wild since 2004, after a mere 16 of the remaining little fluff balls were taken into captivity in an attempt to save their species in 2001.
[partner id=”wireduk” align=”right”]With adults weighing in at under 500g, the pygmy rabbits don’t share the same reputation as their larger cousins: Pygmies do not breed capriciously in the wild. That’s one of the reasons why bringing them back from the extinction feared in the 1990s is such an achievement for the Washington Department of Fish and Wildlife.
Conservation biologists within the department found that the rabbits’ breeding difficulties were down to a vicious cycle of dwindling numbers. Fewer rabbits caused a level of inbreeding within the species, which resulted in a lack of genetic diversity which subsequently lowered reproductive rates and increased the rabbits’ susceptibility to parasites.
Fortunately, the rabbits had southern cousins in Idaho that belong to the same species — although they are genetically distinct and have shown to be separated for more than 10,000 years by fossil and genetic evidence.
Like the Columbia Basin pygmies, the southern rabbits have also been enlisted as endangered but their numbers have improved in recent years. By cross-breeding the Idaho pygmies with the Columbia species the resultant offspring have had better health and their numbers have increased to around 100 rabbits.
These new rabbits, with a genetic makeup of three-quarters Columbia Basin genes and one-quarter Idaho genes, are being gently re-established into the area. Biologists are wary of following the failure of an experimental reintroduction in 2007, when raptors (the bird, not the dinosaur) and coyotes killed rabbits let into the wild.
Instead, a “soft release” strategy is being adopted. First, captive-bred rabbits will be moved to a six-acre enclosure to develop the foraging and burrowing habits needed to survive in the wild while protected from hungry predators. Step by step, the rabbits will move to smaller enclosures while they adjust to the wild, with individual rabbits being released as they become acclimatised.
Newborns will be better-equipped to deal with the wild than their parents raised in captivity, so those pygmies that give birth in the enclosures will have their offspring released before they adapt to human interaction.
Paws’ crossed, the Columbia Basin will soon once more be home to a pile of mini-bunnies.