Saving the Point Arena Mountain Beaver -- Biting Into the Struggle

ESA Assignment Bio 227-01
By: Connor Rudolph

Recovery Plan for the Point Arena Mountain Beaver 

(Aplodontia rufa nigra) 

Picture: Natural Unseen Hazards Blog

1. Summarize Description and Ecology of Organism

     The Point Arena mountain beaver (Aplodontia rufa nigra) is found in a small region of coastal Mendocino County, California. This beaver is small and round in stature; stout. Its height is, on average, 30.5 centimeters and weights between 0.8 and 1.8 kilograms (Steele & Litman). It possesses a large skull, very dense and compressed and has a noticeably flat angle. Both eyes and ears of this animal are small in relation to its body. Thumbs of the forefeet are functionally opposed and all digits of the forefeet possess curved, extended claws (Steele & Litman). One of the telltale signs of this animals is its round short tail.
      There are many different species of beavers, as such there are a number of features that differentiate the Point Arena mountain beaver from the rest. The most observable difference is its vivid black color (Steele & Litman). It's also one of the smallest subspecies of beavers and possesses a unique cranium with distinct measurements. Additionally, the outline of the naval is unique to this organism.
     Point Arena mountain beavers live underground utilizing a type of 'burrow system' use openings under vegetation to get aboveground. The diet of the mountain beaver consists primarily of vegetation so lush greens are essential for its survival.


2. Geographic and Population Changes

     Map of Point Arena Mountain Beaver habitat. Point Arena, California. Located in Western Mendocino County, California.

Picture: Bureau of Land Management

   
     Unfortunately, due to the expansion of cattle grazing in parts of northern California, forest areas have been destroyed, in turn displacing many populations of the Point Arena mountain beaver. Many of the burrow systems mentioned before haven't been seen in many years due to this human intervention (Steele & Litman). There is a direct correlation between human intervention and mountain beaver population as fewer and fewer sightings of this species have been reported. There are an estimated 200-500 individuals left in the species.




3. Listing Date and Type of Listing

Listing Date: December 12, 1991; Federal Register 50 FR 64716 (Arcata Fish & Wildlife Office)

Type of Listing: Endangered (Arcata Fish & Wildlife Office)

4. Cause of Listing and Main Threats to Its Continued Existence

     There are a number of threats affecting the livelihood of the Point Arena mountain beaver. The biggest threats to this species include degradation of land due to development, degradation of land due to grazing, destruction of land due to forest harvest, and continuous pressure by invasive plant species (Steele & Litman). Livestock grazing in parts of Northern California have substantially reduced much of the coastal shrub that is a suitable habitat for the Point Arena mountain beaver (T. Wooster 1997). Trash dumping from urban areas has had a major effect on the mountain beavers' habitat too. More direct threats to this beaver species includes predation by domesticated household animals in the area, poisoning from nearby crops, genetic isolation due to such a small population size, and general disturbance caused by humans.

     The video below highlights the efforts of locals in Point Arena trying to rally people to petition to save this endangered species.

https://www.youtube.com/watch?v=k3CV-vck0JY

5. Description of Recovery Plan

- placement of ramps to protect respective beaver habitats within the Manchester Beach State Park camping area (Steele & Litman).

- North Coastal Regional Water Quality Control Board has began efforts to enhance habitat for the Point Arena mountain beaver whilst an area known as the Garcia River Watershed is being restored.

Picture: U.S. Fish & Wildlife Service

- US Environmental Protection Agency and California Department of Pesticide Regulation are working on a program to reduce the use of pesticides in areas where endangered species (Point Arena mountain beaver) are located.

GOALS: 

- at least 16 populations to are to be protected from human disturbance. Each separate population requires 20 hectares of habitat suitable to their being

- said populations must have a mean density of at least 4 Point Arena mountain beavers per hectare (Steele & Litman).

- every population must be stable and show signs of growth over a period of at least 10 years