Habitat for the pygmy rabbit, a furry denizen of the West’s sagebrush steppes, is in such rapid decline that the species warrants federal protection under the Endangered Species Act, several environmental groups proposed in a petition filed Monday.
Living up to its common name, Brachylagus idahoensis is the world’s smallest rabbit, typically weighing less than a pound. They live in burrows across 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 sage grouse, which the U.S. Fish and Wildlife Service has so far declined to list.
“The species [pygmy rabbit] is highly dependent on sagebrush for virtually all of its winter diet and for cover from predators, and requires deep soil sites for construction of burrows,” states the petition. “Future habitat degradation and loss is predicted, primarily due to an increase in fire frequency in sagebrush habitat in the western portion of the species’ range, which is both driven and compounded by climate change and increases in cheatgrass.”
Filing the petition with FWS are Western Watersheds Project, Center for Biological Diversity, Defenders of Wildlife and WildEarth Guardians. In addition to the ESA listing, it requests the designation of critical habitat for the pygmy rabbit.
“Small enough to fit in the palm of your hand, pygmy rabbits are one of the most endearing and charismatic creatures of the Sagebrush Sea, but unfortunately they are also one of the most at risk of extinction,” said Erik Molvar of Western Watersheds Project. “Our petition demonstrates the serious threats the species is facing throughout its range, and it needs federal protection to ensure its survival into the future.”
The pygmy rabbit is one of six species of rabbit and hare native to Utah, including mountain cottontails and white-tailed jackrabbits. Unlike these other species, pygmy rabbits may not be hunted.
The rabbit now occupies only 10% of its known historic range, which spanned 100 million acres across the America West, according to researcher Miranda Crowell. The historic range includes much of Utah and parts of 12 other states.
“Habitat fragmentation is one of the main issues,” Crowell said. “Because pygmy rabbits are so small, they can’t really travel that far. The maximum dispersal distance that has been found is 13 kilometers.”
A doctoral candidate at the University of Nevada, Reno, Crowell is studying the species’ population dynamics at five sites in Nevada and Oregon.
“The problem is that while one site may pop up with pygmy rabbits that we haven’t discovered before, sites that have been previously occupied are no longer occupied,” Crowell said. “We found a significant decrease in populations over the four years of the study, which was really concerning, and it was a dramatic decrease during that period in all five of our demographic populations.”
Active mostly around dawn and dusk, they tunnel under snow in the winter to safely access the sagebrush that sustains them till spring.
“Pygmy rabbits are slow and thus vulnerable in open areas,” states the petition, authored by Utah-based conservation biologist Allison Jones, the former head of Wild Utah Project, now called Sageland Collaborative. “Pygmy rabbits typically remain in close proximity to burrows. Winter activity occurs within approximately 30 meters of burrows.”
Their leading cause of mortality is predation, with the leading perpetrators being weasels, raptors and owls and coyotes, foxes, badgers, skunks, bobcats and possibly snakes. Being able to hide is critical to rabbits’ survival, but suitable cover is becoming scarce.
Also degrading their habitat are livestock grazing and oil and gas development.
A previous listing petition resulted in a finding of “not warranted” in 2010. Since then, however, the species has experienced fresh setbacks, according to surveys conducted by state wildlife officials across the Great Basin. The Utah Division of Wildlife Resources, for example, developed a monitoring program, with 64 plots established in five locations. In 2011, evidence of rabbit activity was records at 39% of the sites.
These surveys have recorded a troubling decline in habitat occupancy. Alarmingly low occupancy rates of between 7% and 13%, for example, were documented everywhere in Utah outside of the state’s northern region, according to the petition.