1890 - Idaho's Easter Bunny
Pygmy rabbits are found in very patchy distributions in areas with dense, mature sagebrush and deep, soft soils suitable for digging their elaborate burrow systems. Pygmy rabbits are considered “sagebrush obligates” because they require sagebrush to survive. Sagebrush provides protective cover and an important food source for the tiny rabbit, comprising up to 99% of its winter diet. Most herbivores shy away from foraging on sagebrush, which is laden with volatile oils. But the pygmy rabbit has evolved a specialized digestive system to cope with these toxins.
In the decades after Merriam’s Expedition, mammalogists and naturalists generated a trickle of reports describing general characteristics of pygmy rabbits and gradually extended the known range of the species to include the sagebrush deserts of seven westerns states. By mid-20th century, researchers gleaned more details on the species’ life history, behavior, and habitat relationships. These studies identified the pygmy rabbit as a habitat specialist tied to sites of tall, dense big sagebrush and deep soils. By connecting these dots, researchers keyed in on the major limiting factor for pygmy rabbits: habitat fragmentation. Sagebrush habitat across the western U.S. has decreased in area by as much as 55% since European settlement. Within remaining habitat, pygmy rabbits occur in an even smaller subset of remaining patches. So how does a tiny rabbit with limited dispersal capabilities persist in a vast, but highly fragmented habitat?
This looming question and concerns about possible range contractions sparked renewed interest by agencies and researchers to better understand potential threats and conservation needs of pygmy rabbits. In 2002, due to loss of sagebrush habitat coupled with lack of data on distribution and abundance of populations, the Idaho Fish and Game Commission closed the statewide hunting season for pygmy rabbits, and in 2005 the species was listed as an Idaho Species of Greatest Conservation Need. The pygmy rabbit’s elevated conservation status prompted a wave of surveys across Idaho. Idaho Fish and Game databases held fewer than 300 locality records for pygmy rabbit for all years prior to 2002, whereas 3,900 records were collected from 2002-2007. This new information helped the U.S. Fish and Wildlife Service conclude in 2010 that listing the pygmy rabbit under the Endangered Species Act was not currently warranted.
Recent research findings figured prominently in this decision, too. Idaho has been “ground zero” for leading-edge work on pygmy rabbits conducted by Dr. Janet Rachlow and Dr. Lisette Waits with the University of Idaho, Dr. Lisa Shipley with Washington State University, and Dr. Jennifer Forbey with Boise State University and their legions of students. Collectively, the work of these researchers, with support from Idaho Fish and Game, Bureau of Land Management, and the U.S. Forest Service, has furthered the understanding of pygmy rabbit ecology and factors critical to conserving the species by leaps and bounds.
A key ingredient still needed for pygmy rabbit conservation is an effective means to estimate population abundance and changes in abundance over time. This is no small task given pygmy rabbits are secretive, patchily distributed, and their field sign (fecal pellets, burrows, tracks) can easily be confused with other rabbit, hare, or burrowing species. To address these challenges, Idaho Fish and Game, in partnership with University of Idaho and BLM, developed a fecal DNA identification tool and pilot-tested its utility as a survey technique to estimate the proportion of habitat occupied by pygmy rabbit. The technique provided confident identification of species from fecal pellets and minimized survey effort and expense. Some fine-tuning of survey design may be needed, but the technique appears very promising for the thorny task of assessing pygmy rabbit population distributions and trend.
So this spring, when “Peter Cottontail” takes the Easter limelight and animals everywhere are “breeding like rabbits” to pass on their genes, the petite pygmy rabbit will secret away beneath a sagebrush, in the security of its burrow, oblivious to all the holiday fuss. Just as people think of the cottontail rabbit as a symbol of Easter, perhaps we can think of the pygmy rabbit as a symbol for sagebrush conservation and an important part of Idaho’s natural heritage worth protecting for present and future generations.