Columbia Basin Pygmy Rabbit

Sarah Bach

Summarize Description and Ecology of Organism

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The Brachylagus idahoensis, more commonly known as the pygmy rabbit, is a classified member of the Leporidae family. Distinguished from other leporids, the pygmy rabbit is characteristically recognized for its grayish color, rounded ears, and minuscule tail. Coming in at under a pound, these dwarfed critters are identified as the smallest North American leporid. 

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In addition, they are one of the only rabbits known for digging up their own burrows--which requires areas composed of loose soil. Most pygmy rabbits possess more than one burrow with multiple entrances located near the base of the sagebrush plant. These burrows provide both shelter for the rabbits, alongside a nursing sanctuary for the mothers. They depend upon concentrated zones of sagebrush as it is their main source of nutrient. During winter months, pygmy rabbits remain within close proximities to their burrows, traveling further as it warms up during mating season (between February and July). Pygmy rabbits become sexually mature at the age of one-year old, being able to produce a maximum of four litters per year, with a fecundity of 3.5 kits. Their lifespan typically falls between 3-5 years.

(Dense sagebrush habitat)

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Geographic and Population Changes 

(Fragmentation of sagebrush habitat)
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Natively, pygmy rabbits are found living in dense semiarid shrub steppe habitats within western US terrains, specifically, the pacific northwest. Although collectively, the pygmy rabbit is categorized under ‘least concern’ by the IUCN, the subspecies--the Columbia Basin pygmy rabbits, located centrally in Washington State-- became isolated from the pygmy rabbits residing in surrounding states due to the sagebrush habitat being converted for agricultural use. Approximately sixty percent of the original sagebrush habitat in the Columbia Basin area has been converted since for human use. This persistent modification steadily expanded the fragmentation between the pygmy rabbit population and ultimately led to unsustainable numbers in Washington State. By 2002, only 16 Columbia Basin pygmy rabbits remained.

Listing Date and Type of Listing

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In 2001, attention was brought to the staggering Columbia Basin pygmy rabbit population of just 30 rabbits (an 80% decline since 1995). By March 5, 2003, the Columbia Basin pygmy rabbit was officially listed as an endangered species by the U.S. Fish and Wildlife Service (USFWS). By 2004, all wild Columbia Basin pygmy rabbits were extirpated. As of 2008, the last purebred Columbia Basin pygmy rabbit has deceased. The current goal is to stabilize the crossbred population of Columbia Basin pygmy rabbits enough so that they can be reclassified as threatened. 

Cause of Listing and Main Threats to Its Continued Existence

(Common predators of pygmy rabbits)
https://sites.google.com/site/pygmyrabbitjw2012/_/rsrc/1336006239079/
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Approximately, only ten percent of adult pygmy rabbits survive each year due to high levels of predation. Nonetheless, their sustainability level can still maintain a steady rate given that a substantial population is already established and widespread. However, because of the isolation that the Columbia Basin pygmy rabbits face, this staggering percentage proves to be the main contributor to their current listing. 

(Sagebrush catching fire)
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larson.jpg

Although, their high dependency upon sagebrush is an abutting factor to their declining numbers. Sagebrush is highly susceptible to catch fire, resulting in large ranges of habitat fragmentation and destruction. Invasive plant species growing in the area combined with human disturbances have significantly increased the likelihood of fires inciting. Conversion of sagebrush land for agricultural use has also limited the scope of suitable living grounds. This proves to be immensely detrimental, as this further isolates these specialists and prevents expansion. Their localization has resulted in reproductive and skeletal abnormalities caused from inbreeding. This has also led to a decrease in their genetic diversity. Another intrusion on pygmy rabbits’ habitats is livestock grazing. The modifications grazing can cause on the surrounding land has proven to affect the quality and ability for pygmy rabbits to burrow. Although perceived to have relatively lower levels of threat, other contributing factors to the mortality of pygmy rabbits include incidental hunting, burrow trampling, and diseases, specifically coccidiosis which originates from fecal matter and soil and has been an increasing threat to captive bred pygmy rabbits.

Description of Recovery Plan

(Columbia Basin pygmy rabbit in the captive breeding program at the
Oregon Zoo; ears painted to help distinguish the rabbits)
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_basin_pygmy_rabbit_nature_gal.jpg

Captive breeding programs were established to help aid the population growth. In partnership of the Oregon Zoo, Northwest Trek Wildlife Park, and Washington State University; the existing 16 Columbia Basin pygmy rabbits were crossbred with Idahoan pygmy rabbits to increase their genetic diversity and to prevent the arising problem of inbreeding depression (witnessed through skeletal abnormalities), that these pygmy rabbits were facing due to their isolated quarters. Although there was a successful average birth increase of 25%, the WDFW failed to foresee the high mortality rate that would result from reintroducing these captive pygmy rabbits back into the wild. Being in close quarters with humans also resulted in a high possibility of domestication. Modified measures were taken to improve this program. 

(An enclosed release site)
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This includes releasing the captive purebred Columbia Basin pygmy rabbits into large enclosures in order to better monitor fatal influences. In order to control levels of predation, the Washington Department of Fish and Wildlife (WDFW) has taken measures which include, creating artificial burrows, removing nesting grounds, and creating barriers to keep predators, such as coyotes and weasels, out of the sagebrush area. The recovery plan aims to increase the quality and protection of sagebrush in order to provide these pygmy rabbits with suitable habitats needed for reproduction and survival. The objective is to create an undisturbed and unfragmented area of sagebrush with regular monitorization in ensure constant maintained quality, along with reestablishing the free-ranging population. Two sites that are specifically being monitored for their dense sagebrush are Douglas County and Grant County. 

(Members of WDFW monitoring Columbia Basin pygmy rabbits in
Douglas County after a recent fire outbreak on 06/28/17)
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Methods of monitoring the abundance of pygmy rabbits located in the Columbia Basin district include scanning for active burrows and searching for pellets indicating the relative number of individuals present. The Safe Harbor Agreement (SHA) was initiated in 2006 by the USFWS and WDFW to protect sagebrush habitats located on privately owned land. This voluntary conservation agreement states that no impromptu action or intrusion will take place on the owner’s land, so by they follow the instructions of the USFWS and WDFW in preserving the valuable sagebrush land. In return, funding and other incentives will be provided to these landowners for their cooperation. Thus, the recovery plan aims at publicizing the concern of the Columbia Basin pygmy rabbit to civilians and stakeholders in order to raise awareness and funds in order to further protect free-ranging Columbia Basin pygmy rabbits that have wandered onto privately owned land. 

(Pygmy rabbit fitted with a radio collar)
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According to the USFWS, the population size of pygmy rabbits has to sustain at least 500 individuals in order to ensure genetic diversity, with at least 50 of these individuals being sexually mature and adequate of reproduction. Radio transmitter collars will be used to better monitor the activity of these pygmy rabbits and the results will be evaluated to provide the best quality environment needed for a self-sustaining, free-ranging population.

What Can You Do?

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With the continued expansion in development, natural habitats are being destroyed and fragmented at alarming rates. Preventative measures need to be taken in preventing the construction of roads and trails that allow the public ease into otherwise inaccessible areas containing protected habitats. Reducing the number of disturbances will aid the growth and maintenance of dense sagebrush habitats and prevent incidental hunting and destruction of burrows by trampling. Thus, if you are an avid hiker or outdoor explorer, be aware of your imprint on the environment. Stay on the manmade trails, as wandering off may incidentally impair an imperative habitat. 

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In addition, the susceptibility of sagebrush to catch fire is of high concern due to its vitalness to pygmy rabbits. It is necessary to prohibit access to the area in order to prevent accidental fires ignited from recreational activities that can be costly. To directly support the endangered Columbia Basin pygmy rabbit, get involved in volunteering opportunities that aim at preserving and conserving sagebrush habitats. 

Other Resources

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1) The International Union for Conservation of Nature (IUCN) provides the World Database on Protected Areas (WDPA). Before planning a trip, regardless the distance, ensure that your awaited adventure is not intruding upon the wellbeing of your fellow organism by confirming this list of internationally protected areas. https://www.iucn.org/theme/protected-areas/our-work/world-database-protected-areas

2) Seeking an outdoor adventure? Check out American Trials to find hiking trials located all around the U.S. Being mindful of your footprint benefits the survival of integral habitats necessary for endangered animals. https://www.americantrails.org/resources/statetrails/

(Biologists and volunteers releasing captive bred pygmy rabbits back into
the wild)
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3) The Nature Conservancy in Washington State partnered with WDFW in monitoring the wellbeing of pygmy rabbits living in Grant County this past year. To find out about more volunteering opportunities, whether it be directly searching for pygmy rabbits, planting sagebrush, or donating to the cause, The Nature Conservancy provides the resources to get involved. http://www.washingtonnature.org/volunteer-events/2016/7/8/beezley-hills-pygmy-rabbit-monitoring-project

http://www.washingtonnature.org/volunteer

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4) Adopt a pygmy rabbit! A perfect gift to show your appreciation and support for wildlife conservation. Their high dependence upon sagebrush means that specialized grounds have to be grown and preserved in order for their survival. By adopting a pygmy rabbit, you are directly repairing the grounds which have endured metamorphic disturbances.  https://gifts.worldwildlife.org/gift-center/gifts/Species-Adoptions/Pygmy-Rabbit.aspx

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5) Donate directly to help the WDFW with their efforts in recovering the Columbia Basin pygmy rabbit population. Use the subject name “pygmy rabbit restoration” with the address as follows...Fiscal Office, Washington Department of Fish and Wildlife, PO Box 43160, Olympia WA 98504-3160.

Bibliography

 “Columbia Basin pygmy rabbits.” Oregon Zoo, Oregon Zoo, www.oregonzoo.org/conserve/fighting-extinction-pacific-northwest/columbia-basin-pygmy-rabbits.

Oransky, Ivan. “What's Killing the Pygmy Rabbit?” The Scientist, The Scientist, 1 June 2007, www.the-scientist.com/?articles.view/articleNo/25117/title/What-s-Killing-the-Pygmy-Rabbit-/.

“Primack, Richard B., and Anna Sher. Introduction to conservation biology. Sinauer Associates, Inc., Publishers, 2016.

Pygmy Rabbit - Brachylagus idahoensis.”Montana Field Guide, Montana Natural Heritage Program and Montana Fish, Wildlife and Parks, fieldguide.mt.gov/speciesDetail.aspx?elcode=AMAEB04010.

“Pygmy Rabbits in Peril in the U.S.A.” ACTION BIOSCIENCE, American Institute of Biological Sciences, Feb. 2008, www.actionbioscience.org/biodiversity/shipley.html.

Rachlow, J., Becker, P.A. & Shipley, L. Brachylagus idahoensis. The IUCN Red List of Threatened Species 2016, http://www.iucnredlist.org/details/2963/0

Service, U.S. Fish & Wildlife. “WAFWO - Pygmy Rabbit (Columbia Basin DPS).” U.S. Fish & Wildlife Service, U.S. Fish & Wildlife Service, www.fws.gov/wafwo/articles.cfm?id=149489590.

U.S. Fish and Wildlife Service. 2012. Recovery Plan for the Columbia Basin Distinct Population Segment of the Pygmy Rabbit (Brachylagus idahoensis). Portland, Oregon. ix + 109 pp.

https://ecos.fws.gov/docs/recovery_plan/Columbia%20Basin%20Pygmy%20Rabbit%20Final%20RP.pdf