Bunnies go wild
Raised in a special facility, a group of Clackamas rabbits are on the loose, back in their natural habitat
Three lifelong Clackamas residents departed for the sagebrush country of eastern Washington this past week, to begin a new life for themselves - and their species.
The Columbia Basin Pygmy Rabbits, bred in captivity at the Oregon Zoo's secure and undisclosed conservation site in the wilds of Clackamas County, are being re-introduced to their native environment.
'These rabbits are unique: they are the smallest North American rabbit and they are burrowing rabbits,' said Dr. David Shepherdson, division manager of the zoo's Department of Conservation. 'They are a unique part of the sagebrush ecosystem.'
Seven years ago, the handful of remaining wild rabbits was captured to begin the captive breeding program.
'Just after we developed the technology to breed them, they vanished in the wild,' said Shepherdson.
Inbreeding had begun to take a toll on the dwindling population, which has been displaced and isolated by human development.
'The reason the Columbia Basin Pygmy Rabbit is disappearing is primarily agricultural conversion,' Shepherdson explained. 'A lot of the land is being converted to agricultural use. The population became fragmented, which left it vulnerable to disease, fire and predation.'
In 1999, the Oregon Zoo and its partners began an experimental captive breeding program using a close cousin of the severely endangered species: the Idaho Pygmy Rabbit.
'People are surprised that it's been hard to breed pygmy rabbits,' said Shepherdson. 'Other species of rabbits have been kept in captivity by humans for probably thousands of years, but these are different.'
Michael Illig, assistant zoological curator at the Oregon Zoo, described the difficulties.
'We've had many issues with disease. Because they were inbred, they had immune system weaknesses,' he said. 'Every year has been a learning process, and every year we've bred more rabbits.'
The Clackamas conservation site has played a special role in the project. Unlike other breeding sites, where the rabbits live in large, dirt-filled tubs, the Clackamas rabbits have lived in 'burrow boxes' made from plastic coolers, with flexible tubing standing in for their native tunnels.
'We've had less problems with disease out there,' said Illig. 'We add a little dirt for breeding season - just enough for the females to dig burrows.'
In total, 20 rabbits were released. The three from Clackamas were joined by five from the zoo's main facility in Washington Park, with the balance coming from other breeding sites scattered around the Northwest.
'It would be nice to release more, but we think it will be enough,' said Shepherdson. 'We're releasing them right before breeding season - some of the females may already be pregnant.'
Another 75 rabbits remain in the captive breeding program, with further releases planned in the coming years.
'We've almost maxed out on space,' Shepherdson said. 'If we have a bumper crop of bunnies this spring, we could have another release as soon as this September.'
The rabbits are being released back into their native sagebrush habitat in Douglas County, Wash., and artificial burrows were prepared for their arrival. To improve their chances of survival, wildlife biologists have taken steps to reduce the threat from predators in the area - such as removing perches that raptors use to spy their prey.
'A lot of things like to eat pygmy rabbits,' said Shepherdson. 'We've had to do some predator control in advance of their arrival.'
For the scientists and zoologists working to coax the species back from the threat of extinction, this first release marks a major accomplishment.
Rachel Lamson, known to her colleagues as 'The Rabbit Whisperer' for the intuitive connection she shares with the diminutive animals, said: 'I was involved in the capture of these animals seven years ago, so it's pretty exciting to be releasing them back into the wild - it's like coming full circle.'
Illig added: 'What's unique is that we're able to finally release this species back into the wild. That hasn't happened very often - condors, black-footed ferrets and a few others - and this is the second time we've been able to do it.'