Pygmy Rabbit Proposed For Listing Under Endangered Species Act

 

Prime pygmy rabbit sagebrush habitat along the Big Lost River where I lived while working for the Challis National Forest. Photo George Wuerthner 

Years ago, I worked on the Challis National Forest and lived along the Big Lost River in Central Idaho. One of my favorite winter activities was skiing through the big sagebrush stands, where I encountered the pygmy rabbit.

I spent hours watching them from a distance, but try as I might, I never successfully got any close-up photos of these diminutive creatures. As soon as they detected me, they would scurry into their burrows and be gone for the day.

Pygmy rabbit are dimunative. Photo FWS 

These little fur balls are about as cute as can be. For a rabbit, they have tiny ears, and except for white cottontail, they are uniformly gray-matching exactly the dull color of their preferred sagebrush habitat. They are so tiny they will fit in the palm of your hand. If you are familiar with the pika of high elevations, these rabbits are only slightly larger and look similar, though their ears are more prominent.

LISTING UNDER ENDANGERED SPECIES ACT

Recently, several conservation organizations petitioned to have the pygmy rabbit listed under the Endangered Species Act. It has been a long time coming since people have been concerned about the decline in the rabbit population for decades. It was first petitioned for listing in 1991.

The rabbit was again petitioned for listing in 2003, but it was denied by the Fish and Wildlife Service (FWS). In 2007, a federal court found the Service violated the ESA by refusing to protect the pygmy rabbit and ordered the Service to re-examine its decision.

In early 2008, the Service issued a draft concluding that protecting the pygmy rabbit may be warranted. The Service has since refused to issue a final decision.

Pygmy rabbits often come out of their burrow on warm winter afternoons, but they never stray far from the protection of sagebrush. Photo FWS

ECOLOGY AND HABITAT NEEDS

These tiny rabbits are confined to sagebrush habitat. They dig burrows in the soil. In winter, they tunnel to the surface of the snow, and I would often catch them napping near their burrow entrances on sunny afternoons. Once they detected me, they would disappear down the hole.

Typical pygmy rabbit habitat on Little Sheep Creek, Montana. Photo George Wuerthner 

I also used to regularly encounter pygmy rabbits along Little Sheep Creek near Lima in SW Montana whenever I skied in to visit old friends Bill and Susy Leitch, who lived up there for several years.

Map showing the range of pygmy rabbbit. 

Despite these frequent encounters, I did not regularly see pygmy rabbits despite spending lots of time in their Great Basin sagebrush preferred habitat in Central Nevada, southern Idaho, eastern California, SW Montana, SE Oregon, NW Colorado, northern Utah, and SW Wyoming; I have seldom seen them in my rambles.

Big sagebrush (Artemisia Tridentata Tridentata). Photo George Wuerthner

The rabbit is closely associated with big sagebrush (Artemisia Tridentata Tridentata), sometimes eloquently known as the “sagebrush sea” or sagebrush steppe. At least 350 species of wildlife are associated with the sagebrush sea, and in particular, the pygmy rabbit is a sagebrush obligate—meaning it is not found in any other habitat.

Sagebrush provides not only its primary winter food, but dense sagebrush stands offer protection from predators, whether hawks or mammals such as coyotes, bobcats, weasels and badgers.

Sagebrush with forbs (flowers) important for pygmy rabbit summer diets. Photo George Wuerthner 

Some estimates suggest there has been a 50% reduction in distribution and coverage of sagebrush across the West.

When I worked as a botanist for the BLM, we affectionally called big sagebrush Tri Tri. Tri Tri prefers deep soils. As a result, early settlers of the region, looking for favorable places to plow up for hay or other crops, sought out these sagebrush sites. The pygmy rabbit requires the same deep soils for its burrows, and in transferring sagebrush to pasture or hay fields, ranchers eliminate the habitat for pygmy rabbits. Though Tri Tri is the preferred habitat, pygmy rabbits are found among Wyoming big sagebrush (A. t. wyomingensis) and mountain big sagebrush (A. t. vaseyana).

LIVESTOCK GRAZING AND CHEATGRASS

After the initial elimination of big sagebrush for Ag fields, the pygmy rabbit habitat has been further eroded by the invasion of the highly flammable annual cheatgrass (Bromus Tectorum), which has promoted wildfire.

Livestock grazing along the North Fork of the Big Lost River, Idaho–note the near absense of sagebrush or grass. Photo George Wuerthner 

Livestock grazing, which is nearly ubiquitous across the rabbit’s habitat, compounds the spread of cheatgrass in several ways.

First, cheatgrass is favored by soil disturbance—i.e., the “hoof impact” promoted by charlatans like Allan Savory. Hoof impact destroys soil crusts (lichens, bacteria, mosses) that tend to cover the ground between sagebrush plants. In this void enters cheatgrass. However, some research suggests that removing livestock grazing can lead to biological soil crust recovery.

Bluebunch wheatgrass, a common grass in the Sagebrush Sea, does not tolerate heavy grazing. Photo George Wuerthner 

It’s important to note that over much of this sagebrush habitat, large herds of grazing animals, such as bison, have been absent for the last 10,000 years or more. Therefore, many common grass species like bluebunch wheatgrass, Idaho fescue, and other native grasses are intolerant of heavy grazing pressure.

Cattle tend to feast on the native grasses and ignore cheatgrass, giving the invasive alien a competitive advantage for space, water, and light. Thus, the second way that cattle grazing harms pygmy rabbits is by removing native grasses, which favors the invasion of cheatgrass.

As an annual grass, cheatgrass can rapidly colonize burn area, expanding its acreage, and creating even more flammable habitat. This cheatgrass fire cycle is deadly for big sagebrush plants.

 

Aftermath of the Soda Fire that burned tens of thousands of acres of pygmy rabbit habitat in SE Idaho. Photo George Wuerthner 

For instance, over 6,967,500 acres of pygmy rabbit habitat in Idaho has burned in the last 40 years. This loss represents about 4.1% of all presumably occupied pygmy rabbit range in North America. Nevada has suffered even greater sagebrush loss. Over 9,292,750 acres of pygmy rabbit habitat in Nevada have burned in the last 40 years. Surveys of historic pygmy rabbit sites in Wyoming have found a 69% decline in occupation between 2013 and 2019. Similar losses in pygmy rabbit occurrence are documented throughout the West.

Here cattle have trampled a riparian area, and nearby sagebrush stand below the Ruby Mountains in Nevada. Photo George Wuerthner

Livestock use of these lands is a major factor in the cheatgrass-wildfire cycle.

Sagebrush requires many decades to centuries to recover from wildfire fully. The presence of sagebrush obligates like a pygmy rabbit, sage grouse, sage thrasher, and other species and sagebrush itself is clear evolutionary evidence that Indians did not greatly influence western sagebrush landscapes with frequent cultural burning (every 1-10 years), as some commonly assert. If they were burning the land at landscape scales, we would not have big sagebrush or pygmy rabbits.

Highly flammable cheatgrass surrounds sagebrush in the Owyhee Mountains of southern Idaho. Sagebrush does not recover quickly from wildfire. Photo George Wuerthner 

Despite this kind of evidence, many conservation groups and agency personnel have fallen for the Natives and TEK idea they burned everything bandwagon and promote burning sagebrush in the belief they can provide large blazes.

The Sheldon National Wildlife Refuge in northern Nevada is the largest portion of the Great Basin that is livestock-free after cattle were removed 30 years ago. It has the highest known density and occupation of pygmy rabbits in the West. Photo George Wuerthner 

Interestingly, a survey of the Sheldon Wildlife Refuge in northern Nevada, which has been livestock-free for 30 years, had a 53% occupancy rate. This is the highest occupancy rate of any recent pygmy rabbit surveys across the West that was reviewed for the listing petition.

And if pygmy rabbits did not have enough to deal with between sagebrush clearing and wildfire. There is a new threat–evidence that Rabbit Hemorrhagic Disease Virus Serotype 2 (RHDV2) may be present in some populations, causing internal bleeding.

As a result of all these factors, most pygmy rabbit populations are isolated and discontinuous. One of the problems for pygmy rabbit survival is their limited mobility. For instance, rabbits seldom wander more than a few hundred feet from a burrow in winter. However, they do travel further in the summer. Nevertheless, when a small population “winks” out, there is seldom a rescue from nearby populations.

There appears to be some plant quality and quantity synchronization, as females will conceive earlier when green vegetation is available. The females dig a special birthing burrow where the young are born and live.

The females typically give birth to six babies and can have multiple pregnancies in a season and up to three litters a year. I once watched a female nursing her young, and the tiny rabbits swarmed over their mother like a horde of small mice squirming and climbing all over their mom. Such fecundity is necessary as there is a 50% mortality of young within the first five weeks of birth.

Sagebrush dominates the Monitor Valley in Nevada, typical of the Great Basin ecoregion. Photo George Wuerthner 

 

Pygmy rabbits consume sagebrush leaves and, like all rabbits, can reingest feces and pellets to get additional nutrients. In winter, sagebrush makes up 99% of their diet, though in warmer months, they can consume other plants, including grasses and forbs. Given the arid terrain where they exist, pygmy rabbits can obtain moisture from green vegetation and eating snow.

Pygmy rabbits should be listed. But unless the BLM eliminates livestock grazing from OUR public lands, I do not have much hope that the rabbits, much less other sagebrush obligates like sage grouse, have a real chance of avoiding extinction across much of their range.

Cow bombed wet meadow and sagebrush site in the Alta Toquina Wilderness, Nevada. Photo George Wuerthner 

A study in Washington’s Columbia Basin found that ungrazed areas contained significantly more burrows per unit area than did grazed areas. Vegetation composition and structure differed little among treatments in early summer before annual grazing by cattle. However, late summer through winter cattle grazing removed about 50% of the grass cover, reducing nutritional quality. The authors concluded that “removing cattle grazing from key habitat locations may benefit efforts to restore this rabbit in Washington.”

The dense grass cover is cheatgrass which is taking over much of the sagebrush habitat in the West by frequent burning that destroys sagebrush seen in the middle of the photo. Photo George Wuerthner 

Even eliminating livestock is unlikely to stop cheatgrass spread. Still, it might slow the transition of sagebrush to cheatgrass down enough, which, combined with strong efforts to reverse climate warming, might give these small creatures a chance to survive into the next century.

VOLUNTARY GRAZING PERMIT RETIREMENT

The Voluntary Grazing Permit Retirement proposal could be targetted to remove livestock from critical pygmy rabbit habitat. Writing your Congressional representatives to endorse this plan could help save the pygmy rabbit from extinction.