The world’s smallest rabbit may be at risk of extinction, groups warn

The dwarf rabbit now occupies just 10% of its historical range in the Great Basin, according to a petition seeking an endangered listing.

The habitat of the dwarf rabbit, a furry denizen of the sagebrush steppes of the west, is declining so rapidly that the species deserves federal protection under the Endangered Species Act, several environmental groups suggested in a petition filed Monday.

Living up to its common name, Brachylagus idahoensis is the smallest rabbit in the world and usually weighs less than a pound. They live in burrows throughout the Great Basin, including western Utah. But climate change and invasive weeds are altering this landscape in ways that could threaten the survival of the pygmy rabbit, not to mention many other species, including the sage grouse, which the US Fish and Wildlife Service has so far refused to list.

“The species [pygmy rabbit] is highly dependent on sagebrush for virtually all of its winter nutrition and protection from predators, and requires deep soil sites for burrowing,” the petition reads. “Future habitat degradation and loss is predicted, primarily due to an increase in fire frequency in sagebrush habitat in the western part of the species’ range, both driven and amplified by climate change and increases in cheatgrass.”

The petition to FWS is being submitted by the Western Watersheds Project, the Center for Biological Diversity, Defenders of Wildlife and WildEarth Guardians. In addition to the ESA list, she calls for the designation of a critical habitat for the pygmy rabbit.

“Small enough to fit in the palm of your hand, dwarf rabbits are one of the Sagebrush Sea’s most endearing and charismatic creatures, but unfortunately they’re also one of the most endangered,” said Erik Molvar of the Western Watersheds Project. “Our petition demonstrates the serious threats the species faces throughout its range, and it needs federal protection to ensure its future survival.”

The dwarf rabbit is one of six rabbit and hare species native to Utah, including mountain rabbits and white-tailed hares. Unlike these other species, dwarf rabbits are not allowed to be hunted.

According to researcher Miranda Crowell, the rabbit occupies only 10% of its known historical range, which spanned 100 million acres in western America. The historical range includes much of Utah and portions of 12 other states.

“Habitat fragmentation is one of the main problems,” Crowell said. “Because dwarf rabbits are so small, they can’t travel that far. The maximum propagation distance found is 13 kilometers.”

A graduate student at the University of Nevada, Reno, Crowell studies the species’ population dynamics at five sites in Nevada and Oregon.

“The problem is that while a site is popping up with dwarf rabbits that we haven’t previously discovered, sites that were previously occupied are no longer occupied,” Crowell said. “We found a significant population decline over the four years of the study, which was really concerning, and it was a dramatic decline over that period in all five of our demographics.”

They are mainly active at dawn and dusk, burrowing under snow in winter to safely access the sagebrush, which feeds them until spring.

“Dwarf rabbits are slow-moving and therefore vulnerable in open areas,” says the petition, written by Utah-based conservation biologist Allison Jones, former director of the Wild Utah Project, now called the Sageland Collaborative. “Pygmy rabbits usually stay in close proximity to burrows. Winter activity occurs within about 30 meters of caves.”

Their main cause of death is predation, with the main perpetrators being weasels, birds of prey and owls and coyotes, foxes, badgers, skunks, bobcats and possibly snakes. Being able to hide is essential for rabbits to survive, but suitable cover is becoming scarce.

Livestock grazing and oil and gas exploration also affect their habitat.

An earlier listing application in 2010 led to the finding “not justified”. Since then, however, the species has suffered fresh setbacks, according to surveys conducted by state wildlife officials across the Great Basin. For example, the Utah Division of Wildlife Resources developed a 64-plot monitoring program in five locations. In 2011, evidence of rabbit activity was recorded at 39% of sites.

These surveys have identified a worrying decline in habitat occupancy. Alarmingly low occupancy rates, for example between 7% and 13%, have been documented throughout Utah outside of the state’s northern region, according to the petition.