PYGMY RABBITS: SMALL SW WYOMING MAMMAL RECEIVING GROWING ATTENTION

12/16/2005

GREEN RIVER – Pygmy rabbits.

OK. The name isn’t very flattering like, perhaps, their relative the snowshoe hare or even the cottontail. (Can you imagine children singing, “Here comes Peter Pygmy Rabbit, hopping down the bunny trail”?) 

You can’t hunt the diminutive inhabitant of southwest Wyoming, soand most folks don’t even know the sub-species exists.  The name doesn’t invoke rapid changes in blood pressure to the extent as the mention of, let’s say, the grizzly bear or gray wolf. Yet all three species warrant some form of protection. The animals remind us about the basic concept of how all species are interrelated and why all wildlife needs protected.

                In fact, there is growing concern for the conservation of the pygmy rabbit. Its most important habitats face  with a high potential for habitat loss due to conversion of sagebrush communities to grazing lands and oil and gas developments. The pygmy rabbit has been considered a “Species at Risk” by the U.S. Fish and Wildlife Service since 2002. In 1996, the Wyoming Game and Fish Department declared the pygmy rabbit a “Species of Special Concern.”

                Like the greater sage grouse and Gunnison sage grouse of the sagebrush West, pygmy rabbits are declining in numbers. “I was thinking (perhaps wishfully) that discovering more detailed information about pygmy rabbits could help biologists understand other sagebrush obligate (reliant on sagebrush) species and lead to better management of the species and its habitats,” said Lucy Wold, Wyoming Game and Fish Department information specialist in Green River. “That’s when I was introduced to University of Wyoming graduate student Melanie Purcell. Purcell is studying pygmy rabbit distribution throughout southwest and central Wyoming. I have since realized now the situation is a lot more complicated than it appears.” 

         Pygmy rabbits (Brachylagus idahoensis) are the smallest member of the fFamily Leporidae (hares and rabbits) and make their home in the West. They are gray in color with a small, buff-colored tail, which, unlike the cottontail, is difficult to see. Pygmy rabbits are distributed throughout most of the Great Basin and some of the adjacent intermountain region, including portions of Washington, Oregon, California, Nevada, Utah, Idaho, Montana and Wyoming. The species eat mostly sagebrush (up to %99 percent of its winter diet) with a small portion of grasses and forbs consumed. Until recently, there has not been an abundance of pygmy rabbit research or data available. 

                “Pygmy rabbits are unique among the rabbit family and are quite interesting creatures,” says Purcell. “They are the only rabbit in North America known to dig their own burrows.  They are territorial with only one rabbit occupying a burrow complex, except during the breeding season when a pair occupies a complex. Pygmy rabbits have even been known to chase cottontails and jackrabbits out of their burrows. They only have two litters per year with 4-6 young per litter. The mother digs a separate burrow where she has her young and then backfills the hole to protect them.” 

                To date there has only been one study of pygmy rabbits conducted in Wyoming. Another UW graduate student, T.E. Katzner, completed the study in 1997 at Fossil Butte National Monument near Kemmerer. Purcell says there is little information quantifying habitat characteristics for pygmy rabbits and none of the information applies specifically to Wyoming. The winter study at Fossil Butte provides some baseline data for habitat characteristics, however, it is a protected area and habitat associations may be different than in managed landscapes. Currently, there is no quantitative data to compare habitat in different areas of Wyoming.

                Pygmy rabbit populations may fluctuate locally and perhaps regionally in response to environmental conditions and are subject to long-term changes.  In Idaho and Washington, a gradual decline has been attributed to climatic and vegetative changes since the end of the ice ages and has been accelerated by human activities. Purcell’s three-year study will identify pygmy rabbit distribution in southwest and central Wyoming and habitat characteristics.

                “We’re studying habitat associations of the pygmy rabbit at 10 geographically separate study sites,” says Purcell. “Each site is a paired site consisting of a pygmy rabbit use area and a pygmy rabbit non-use area. Habitat sampling data was collected at pygmy rabbit use sites and adjacent non-use sites to quantify habitat use and availability within each site.”

She explained there are 10 locations at each site (10 use and 10 non-use) where habitat measurements are conducted. Each location has five vegetation points, one in the center, and one 10 meters in each direction.  This will provide each sample with a set of sub-samples to achieve a better estimate of the characteristics for each of the samples.  

                Purcell and her co-workers spent the 2005 field season mapping the boundaries of the distribution of pygmy rabbits within Wyoming and habitat characteristic measurements, including sagebrush such as height and cover, as well as cover of grasses and forbs, bare ground and litter. Soil samples were obtained from various depths. 

                “Pygmy rabbits appear to be habitat specialists,” she says.  “Field observations suggest that soils play an important role in affecting pygmy rabbit distribution patterns. The specific types of sites where pygmy rabbits build their burrows infer a relationship between the rabbits and the soils. Sites where pygmy rabbits were commonly observed were in three types of habitats: sand dunes, mima mounds (remnants of mounded soil and vegetation left over from the last ice age) and riverbanks.”

                Pygmy rabbits were found beyond their previously known distribution in Wyoming. The known range has been extended east as far as Rawlins, south toward Baggs and north toward Riverton. Geographic information system maps showing pygmy rabbit distribution and quantification of habitats used by pygmy rabbits within Wyoming will be updated as a result of the surveys conducted.

        Now entering the third year of the study, Purcell is confident the results from this study will benefit the state of Wyoming and open up opportunities for further research on pygmy rabbits within Wyomingthe state. .      “The pygmy rabbit may not seem like it should be a species of concern, but conservation of any species, no matter how insignificant they may seem, is important because even small changes in an ecosystem can sometimes have larger, long-term impacts, which can ultimately affect humans.”    

      “It has been exciting learning about such a unique species. It was interesting to see the specific, yet similar types of habitat they are using. All areas had sagebrush, but they were specifically found in tall, dense sagebrush, on sand dunes, on mima mounds, in drainages, and in swales or patches of sagebrush that are often in the deposition areas of hillsides and rims. They are so small (300-500 grams) and holding them in your hands is an awesome and humbling feeling. I am grateful to have had the opportunity to work on pygmy rabbits.  I think we continually grow through our experiences and this opportunity has enlightened me in many ways.”

                So, there you have it. In this case, the answers to some complex interrelationships might just be in the soil. We can all learn from something as small as a pygmy rabbit. Even if it just makes us take a closer look at the sagebrush we take for granted.

                For more detailed information on Purcell’s study visit the Game and Fish Web site at   and click on Green River Region Office News.

(contact: Lucy Wold (307) 875-3223) (photos available)

-WGFD-