A dwindling population of rabbits, isolated in Washington since the ice age, may need help from Idaho relatives to survive.
With no nearby relatives for recolonization, scientists are considering breeding Columbia Basin pygmy rabbits with their pygmy rabbit cousins in Idaho to save them from extinction. Researchers estimate fewer than 100 Columbia Basin pygmy rabbits are left in the wild, Lisette Waits, University of Idaho wildlife resources professor, told the Statesman.
“These rabbits, particularly in Washington, are facing a lot of challenges,” Waits said.
The pygmy rabbit is the smallest rabbit species in North America. Weighing less than 1 pound, the softball-sized mammal was first observed in Idaho — hence its scientific name, Brachylagus idahoensis — but inhabits the larger Intermountain West in extensive burrow networks.
The tiniest and rarest of this species lives in Washington’s Columbia River Basin, subsisting on one of Central Washington’s last-remaining patches of sagebrush. Glaciers isolated the state’s endangered pygmies from relatives about 10,000 years ago, Waits said.
Shrinking sagebrush threatens pygmy rabbits
Scientists estimate the Gem State has the second-largest area occupied by pygmy rabbits, behind Wyoming. The rabbits primarily reside in the eastern, central and southwestern parts of the state.
Assuming they breed like rabbits, the Washington clan could survive with the help of Idaho relatives. Scientists tried this plan before with some success.
When the Columbia Basin population nearly approached extinction two decades ago, scientists bred the remaining 16 rabbits with pygmies from Idaho and other Western states, eventually releasing the next generations in the wild.
Ever since, University of Idaho researchers have been traversing Central Washington’s sagebrush, tracking the rabbits’ burrows and feces. In the lab, wildlife resources students such as Jon Dixon construct a “barcode” from genomes in the pellets to track individual rabbits year after year.
“They are pretty skittish,” Dixon said about the rabbits, which fit in the palm of his hand. “When you see them, they start to bolt.”
With floods and fires, monitoring might not be enough to protect Washington’s miniature rabbits, which are once again disappearing.
There are no specific plans yet for introducing the out-of-state rabbits. The process is complicated, Waits said, because states need enough rabbits to share without contributing to declines.
More research might be needed before Idaho lends its rabbits to Washington. There’s limited data on pygmy rabbit population changes over time, said Janet Rachlow, University of Idaho professor of wildlife ecology. But anecdotally, people have documented declines.
“They’re pretty secretive,” Rachlow told the Statesman. “They’re very good at hiding.”
How to spot Idaho pygmy rabbits
Keen-eyed Idahoans can spot the tiny rabbits in the sagebrush. In late summer, baby rabbits are plentiful, and in the winter snow, their tracks stand out.
Pygmy rabbits are tightly coupled to sagebrush ecosystems, Rachlow said. The rabbits rely on the aromatic shrub for shelter, and it’s their primary food in the winter, Rachlow said. The tiny critters have even adapted to consume the plant’s natural toxins, which give it a distinct cool, sharp smell.
Scientists expect the rabbits to be impacted by changes to their habitat, Rachlow said, and fire, invasive plants, energy systems, and changes in land use have contributed to shrinking sagebrush across the West.
Apart from a potential trip to Washington, pygmy rabbits typically are not very mobile, Jennifer Forbey, Boise State biological sciences professor, told the Statesman. The rabbits become accustomed to eating the particular shrubbery surrounding their homes. If their sagebrush shelter disappears, they may have difficulty finding another place with ample food and deep enough soil to burrow.
The critters are a cute, critical species in the West’s landscape but are sometimes underappreciated compared to flashier species like the sage-grouse, Forbey said.
“I think the pygmy rabbit gets kind of forgotten,” Forbey said.