The Elusive Riparian Woodrat - Galen Amick

Gneotoma fuscipes riparia

Ecology

The Riparian Woodrat, neotoma fuscipes riparia  also know as the San Joaquin Valley Woodrat is a native of the San Joaquin Valley of California. He's a subspecies of the Dusky-footed Woodrat. The Riparian Woodrat differs from his relatives in that he is a bit more robust and has a bicolored tail that is furred and not scaled like other common rats. He is tips the scales at a whopping 7-14 ounces! 
Riparian Woodrats are herbivores that feed predominately on juniper. Although they're know as generalist herbivores who are known to eat a plethora of fruits, nuts, and other foliage. The Dusky-footed Woodrats are renowned for making large dwellings from sticks and foliage. Their spacious dwellings are built on the forest floor, between the roots of an evergreen, or against a hollowed log. Their shelters range from 2-5 feet high with a diameter that can reach up to 8 feet. There are Woodrat homes that lasted more than 20 years.  

Dusky-footed Woodrats live in loosely cooperative societies, females usually remain close to their birth dens while the males disperse and become very aggressive and territorial during the mating season. These two instincts create mostly female populations with the males having multiple mates. Riparian Woodrats dwell in and around evergreens and live oak. However,  they tend to forage through thick shrubs in the.......Riparian Zone! W hich is the area between a river and surrounding forrest. 

Geography & Change in Population

Riparian Woodrats have a much smaller range now than  80 years ago.  The only verified population lives in a 250 acre area of Riparian Forest along the banks of the Stanislaus River within the Caswell Memorial State Park. The size of this population was 437 in 1993(Williams). There is no known data on the actual reduction in population size because its uncertain what the current population currently is. 

It is known however, that the Riparian habitat within the San Joaquin Valley is a skeleton of its former self, habitat loss and fragmentation are the primary causes in the Riparian Woodrat population. 

When did the Riparian Woodrat become endangered?

February 23, 2003 the Riparian Woodrat was listed as a Region 8 Endangered Species.

Threatening the future of Riparian Woodrats: 

We are the the primary reason for the decline and fragmentation for their population. Construction of large dams and canals to divert water for irrigation has caused the central valley rivers to become streams or dry up completely. More of their habitat was lost to riverbed cultivation. Lastly its likely that livestock trampling and grazing Riparian zones in the central coast leads to more habitat loss. 

In the current drought conditions flooding also poses a threat to the Riparian Woodrat. They are great climbers and sometimes nest in trees but most nests are on or near the ground and their stick dwellings are critical to their survival . 

Lastly the isolated and relatively small population bring up concern for risk of inbreeding. 

Road to Recovery

The recovery plan is focused on the reduction and reversal the population fragmentation. This would eradicate the risk of disease and reduced fitness due to inbreeding. First other populations need to be found, it is suspected that they exist throughout other areas of the San Joaquin Valley. The issue is that most of the riverfront land in the valley is privately owned. The plan requires getting access to the privately owned land to locate other populations as well as encouraging landowners to partner in a conservation plan for the populations. 

Actions required for recovery:

1. Survey and Mapping of Riparian Areas in the San Joaquin River Valley

2. Development of Riparian Vegetation conservation incentive program

3. Habitat restoration program

4. Genetic study of the Caswell Memorial State Park Woodrat population 

5. Establish conservation agreements with landowners for conservation 

6. Begin to restore and link riparian habitat and introduce woodrats

What Can You Do?

It's likely that some of the families that own large plots of land in the valley containing Riparian Habitat have family members that go to school here at calpoly. The best thing you can do is spread the word about Riparian Woodrats and the encourage your friends or family to do the same so that recovery continues. 

Sources:



"The endangered species recovery program"Choice Reviews Online 42.08 (2005): n pag. Web.

 "Species Profile for Riparian Woodrat (Neotoma Fuscipes Riparia)." Species Profile for Riparian Woodrat (Neotoma Fuscipes Riparia). N.p., n.d. Web. 05 Dec. 2015.

Kelly, Patrick A. "CONSERVATION PRINCIPLES FOR THE RIPARIAN BRUSH RABBIT & RIPARIAN WOODRAT." Bay Delta Conservation Plan. CSU, 12 July 2011. Web. 2 Dec. 2015.