Cooperative Extension Service Communications and Technology Department 3354 1000 E. University Ave. Laramie, WY 82071 (307) 766-6342 • fax (307) 766-3998 • www.uwyo.edu

 

For Immediate Release

 

 

Contact: Steven L. Miller, Senior Editor

Phone: (307) 766-6342

E-mail: slmiller@uwyo.edu

Archived News Site www.uwyo.edu/agadmin/news/news.htm

 

Date: March 28, 2006

 

UW student’s effort to determine pygmy rabbit habitat no pint-size task

            The heat of high summer in Wyoming would linger into the evening as Melanie Purcell and her crew wrapped their pygmy rabbit traps in burlap to place amidst the sagebrush-spotted landscape.

            Purcell, a University of Wyoming zoology graduate student from Longmont, Colo., draped burlap around wire box traps to make them look more like the burrows the pygmy rabbits dig, and then they were placed beside burrow entrances. Pygmy rabbits, Brachylagus idahoensis, are the only rabbits in North America known to dig their own burrows.

            Purcell baited the traps with apples. She’d check the traps in the morning after 8. The traps were set in the evening because literature suggests the rabbits are active at dawn and at dusk. She would find out the dawn-and-dusk habit may be true in other environments where the rabbits are found – the Great Basin states – but she routinely observed Wyoming rabbits several times a day.  She would also begin to realize the soils where the rabbits lived were related to their distribution.

            Purcell is working closely with College of Agriculture Department of Renewable Resources Professor Stephen Williams, a member of her graduate committee.  Although Williams is not a zoologist, he does work with soils and the biology of soils, and thus the interest in the connection with Purcell’s project.

            The pygmy rabbit is designated as endangered in the Columbia Basin Distinct Population Segment by the U.S. Fish and Wildlife Service and is listed as a species of special concern in Wyoming by the Wyoming Game and Fish Department (G&F).

            Oil and gas development in southwestern Wyoming heightened interest in the pygmy rabbit and also has produced Colorado sightings south of Wamsutter that can’t be confirmed.

            The rabbits were not documented in Wyoming until 1981, although they may have been previously mistaken for small cottontails and not identified as an entirely different rabbit. They are found only in the southwestern and central portions of the state.

            Purcell had conducted pygmy rabbit survey work for the Wyoming Natural Diversity Database, and when the G&F and federal Bureau of Land Management (BLM) wanted someone to examine the distribution of the pygmy rabbit, she hopped at the chance.

             “I knew their characteristics were different compared to other rabbits,” Purcell noted. “They exist in patchy areas and are sagebrush obligates – they eat entirely sagebrush. Also, I was interested in this project because I thought it would be exciting to be one of the first people to do research on them in the state and build a basic understanding of where they exist and what types of habitats they are using.”

            Purcell had to find and document them first. Their easternmost boundary is believed to be near Farson, about 40 miles north of Rock Springs. Her team drove back roads and hiked endlessly to look for habitat and presence or absence of pygmy rabbits.

            The group surveyed south of Interstate 80 between Rock Springs and Baggs and north of I-80 between Farson, Riverton and Rawlins. She used a handheld Global Positioning System unit to map approximately 200 locations and plotted about 900 GPS points.

            Only one rabbit characteristically occupies a burrow complex, which usually ranges from two to 10 burrows, but four to five burrows are more common; however, a rabbit pair will occupy the same burrow complex during the breeding season. The rabbits breed in late winter and early spring and can have up to two litters per year with up to six young per litter. They finish reproducing by June.

            They are called pygmy for a reason. “The largest rabbit I caught was slightly over a pound. Really little! They would fit into the palm of your hand,” she says. “The length was just less than 7 inches. They were all brown with short, brown tails rather than the puffy, whitish tails like cottontails, and their ears are more rounded. They look almost like a pika with more of a rabbit look.”

            Their range is about 33 to 55 yards from their burrows, which are thought to go as deep as about 40 inches.

            The rabbits appear to favor areas having thick sagebrush with deep, soft soil. Some selected habitats include sand dunes where sagebrush exists or on mima mounds where sagebrush is thicker and taller than the surrounding sagebrush (mima mounds are remnants of ice-wedges left from the last ice age).

            Elevation seems to play a role along with hydrology and types of soils in the distribution of these animals. “In Wyoming, we are finding them between 6,500 to 7,500 feet; however, in places like Nevada and Utah, they are found between 4,000 to 7,000 feet. The climate is different there. The types of sagebrush found in Wyoming at that elevation exist at lower elevations in other states.”

            Purcell said mountain chains lacking sufficient sagebrush cover and soil may also be a barrier to pygmy rabbit migration.

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