Sierra Nevada Bighorn Sheep

Sierra Nevada Bighorn Sheep 

Ovis Canadensis ssp. Sierrae

Calvin Koleszar

               Bighorn Sheep, one of the Golden States' most iconic animals, is under threat of extinction. In the Sierra Nevada Mountain Range, they are even more threatened than other populations in California. Although seen as a different species in comparison to its Southern California relatives, they are relatively the same in nearly all aspects except horn differentiation. 

               According to The California Department of Fish and Wildlife, by 1995 only 100 Sierra Nevada Bighorn sheep remained in sixteen distinct and historic herds. However, due to successful breeding programs and recovery plans, the population has risen to about 600 as of 2014. The map shown above is the current population distribution for the species. The Sierra Nevada Bighorn encompasses a large range of habitats from alpine meadows, rocky mountainsides, and summit plateaus. They tend to avoid dense vegetation for fear of predators. 

               Their population decline can largely be attributed to diseases from livestock in the central valley, predation, unregulated hunting, and habitat destruction. Populations went from a historic population of an estimated 1,000 pre 1900 and dropped dramatically in the twentieth century. The lowest it got was an estimated 100 in 1995, with only five herds remaining. Due to recovery efforts, herd populations have increased to encompass Yosemite National Park, Sequoia-Kings Canyon National Park and four national forests in the area. 

               The recovery plan, first implemented in 2007, has brought tremendous results within the populations. Starting in 2007, the population went from roughly 100 since 1999, to about 500 in 2012 and to about 600 in 2014. This is due in part to the California Department of Fish and Wildlife Service, along with other federal bureaucracies, management of: (1) Management of disease risk from domestic sheep, (2) translocations (augmentations and reintroductions) to increase bighorn numbers and their geographic distribution, (3) predator management to limit predation on bighorn sheep, and (4) monitoring and management of genetic variation. They have been exercised in the areas in the map above. With continued anthropogenic help, populations should continue a healthy increase within the next decade. It has been extremely successful so far. Along with that, there have also been reproduction programs to increase different heard sizes by taking female sheep from one group that has a surplus of females and implementing them into other groups that are lacking females and genetic diversity. 

               The way to sustain these populations so they may have a healthy future without the influence of humans is to limit the livestock entering their domain and spreading deadly diseases to the Bighorn Sheep. Now that there are tag limits for hunting, Bighorn Sheep are a lot less susceptible to becoming trophy ornaments. With time and spreading female sheep between herds, genetic diversity should naturally make these populations healthy and sustainable. Locals can also do their part by just staying away from these animals. Interaction with humans and outside species have taken drastic tolls on the Sierra Nevada Bighorn Sheep and if we are to see these populations thrive in the future, we need to let them grow once they become stable enough. 

Works Cited

"Recovery Program." Sierra Nevada Bighorn Sheep Facts - California Department of Fish and Wildlife. N.p., n.d. Web. 03 Dec. 2016.

"Recovery Plan for Sierra Nevada Bighorn Sheep." N.p., n.d. Web.

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Columbia Basin Pygmy Rabbit - Jae Lee

Please Protect this Precious Rodent, it is Innocent and Furry

(Washington Fish and Wildlife Office)

The Columbia Basin Pygmy Rabbit
A member of the family of hares and rabbits, Leporidae, the pygmy rabbit is the smallest leporid in North America. The species is notable for its small stature, small features, and gray coloration. The pygmy rabbit's diet consists of mainly sagebrush; relying on it for nearly half its meals in the summer, and consuming almost exclusively sagebrush in the winter (Washington Fish and Wildlife Office). Pygmy rabbits are the only leporids that dig their own burrows, which it uses to take shelter from predators including foxes, badgers, bobcats, and birds of prey (U.S. Fish and Wildlife Service). 

Geographic and Population Changes

Approximate historical distribution of the pygmy rabbit (U.S. Fish and Wildlife Service)

The pygmy rabbit has resided in the Great Basin's shrub steppe biomes in the western United States for more than 100,000 years. Pygmy rabbits have occured in several states including California, Oregon, Nevada, Wyoming, and Montana; however, fossil records indicate that gradual climate change restricted the pygmy's range as sagebrush grew less abundant (U.S Fish and Wildlife Servvice).

Listing

• Classified as a threatened species: 1990 (Washington State)
• Classified as an endangered species: 1993 (Washington State)
• Classified as an endangered species: 1995 (Washington Department of Fish and Wildlife)
• Emergency Federal Listing as an endangered species: 2001 (U.S. Fish and Wildlife Service)
• Final rule listing as an endangered species: 2003 (U.S. Fish and Wildlife Service)

Threats

1. Habitat Destruction
   Land development and irrigation has fragmented the Columbia Basin habitat that the pygmy rabbit calls home. Fragmentation restricts the rabbits' range of movement and ability to disperse. Urbanization has converted approximately 60% of the original Columbia Basin shrub steppe habitats, taking away over half of the pygmies' former residences. Its burrows also are shallow enough that walking across one could collapse the shelter entirely.
2. Sagebrush Dependence
   Due to the pygmy rabbit's specialized diet, the vitality of the sagebrush population directly affects the pygmy population. New invasive species of flora in the Columbia Basin provide easy fuel of fires that decimate the sagebrush that the pygmies rely on.
3. Predation
   While pygmy rabbits have adapted the wide variety of predators they face, due to the small size and centralized presence of the population, even normal levels of predation pose a threat to the current Columbia Basin pygmy rabbits.
4. Disease
   Pygmy rabbits are highly susceptible to parasites making them vulnerable to disease. Even in captivity numerous deaths in domestic Columbia Basin pygmies have been related to disease. Coccidiosis and mycobacteriosis are two commonly reported illnesses in pygmy rabbits, with other conditions such as brachydactylia under further investigation. 

Recovery Plan

The originally defined phases of the pygmy rabbit recovery program were stated as:
1. "Removal of abatement of imminent threats in order to prevent the extinction of the Columbia Basin pygmy rabbit."
2. "Reestablishment of an appropriate number and distribution of free-ranging subpopulations."
3. "Establishment and protection of a sufficiently resilient, free-ranging population that would be expected to withstand foreseeable long-term threats."

With these ideas in mind, the ultimate goal of the recovery plan is the remove potential threats to the Columbia Basin pygmy rabbit, and eventually have the species removed from the Federal List of Endangered and Threatened Wildlife and Plants (U.S. Fish and Wildlife Service).

Action 1. Focus on captive breeding of Columbia Basin pygmy rabbits
Action 2. Reintroduce pygmy rabbits back to the Columbia Basin ecosystem
Action 3. Search for remaining wild Columbia Basin pygmy populations
Action 4. Protect free-ranging pygmies by removing predators and other threats
Action 5. Protect pygmy rabbit habitats and recovery areas
Action 6. Negotiate with landowners within the pygmy rabbit's historical distribution
Action 7. Address general public to garner support for recovery efforts
Action 8. Establish funding for recovery efforts
Action 9. Revise Recovery Plan as necessary

What can you do?
One of the National Wildlife Federation's priorities is protecting existing sagebrush habitats for potential pygmy populations to occupy (National Wildlife Federation). You can donate to the National Wildlife Federation to help fund efforts to conserve the sagebrush habitat for pygmy rabbits and other species that live there.

References
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.

Washington Fish and Wildlife Office, U.S. Fish & Wildlife. "WAFWO - Pygmy Rabbit (Columbia Basin DPS)." WAFWO - Pygmy Rabbit (Columbia Basin DPS). U.S. Fish & Wildlife Service, n.d. Web. 01 Dec. 2016.

Federation, National Wildlife. "Return of the Mighty Pygmy Rabbit - National Wildlife Federation." National Wildlife Federation. National Wildlife Federation, n.d. Web. 01 Dec. 2016.