Salt Marsh Harvest Mouse

Megan Dunlop

The Salt Marsh Harvest Mouse
Reithrodontomys raviventris

Description and Ecology of Organism
-Description: Rodent with grooved upper front teeth, and cinnamon to red colored fur. There are two subspecies, a Northern variety and a Southern variety.

-An adult's length is twelve to eighteen centimeters (5 to 7 inches) and a tail length of six to ten centimeters (2 to 4 inches)

-Weight of a mature mouse is approximately 10 to 20 grams (0.35 to 0.7 ounces)

-Nocturnal

-Makes tunnels and enjoys living in glasswort plant 

-Predators: hawk, snake and owl species, as well as shorebirds and larger mammals
      -Domestic cats have been becoming a threat due to increased developed land

-Competent swimmer

-Can tolerate salt in its food and water supply

-Drinks salt water and sometimes even prefers it to fresh water!

      -Eats seeds and plants
 -Lives 8-12 months

      -Only has about 4 offspring per litter and only about once a year

 Geographic and Population Changes

-Endemic to the San Francisco Bay Area salt marshes

-Northern Variety lives in the marshes of the San Pablo and Suisun bays

-Southern Variety lives in the marshes of Corte Madera, Richmond, and South San Francisco Bay

-Need thick vegetation cover, specifically vegetation that thrives in salt water

-If salinity is low, these plants die off and lead to lower populations of mice

-Not aggressive animals, so they can live in high population density as long as their essential life needs are met

-Can survive tidal flooding because they can swim, float, and climb

Listing Date and Type of Listing

-Federal listing: October 13, 1970

-CA listing: 1971

-Recovery Priority ranking of 2C

-Recovery Plan originally made in 1984, updated in February 2014

Cause of Listing and Main Threats to its Continued Existence

-Endangered because of its limited habitat, only lives in salt marshes in the SF Bay area

-Human land development is destroying their very limited habitat

-Historic decline in population

-Pollution, boat activity, commercial salt harvesting, decrease in native plants

-Increased predation

Ex: the recovery actions of the peregrine falcon have caused the mice population to suffer

Landfills attract birds such as seagulls and ravens who prey on mice

Description of Recovery Plan

-Protected habitat within wildlife refuges throughout the Bay Area

-Specific protection strategies for different cities

            Ex: San Rafael: No development within 50 feet of the shoreline
-Actions to Recovery include:

• Government possession of all "existing, historic, and restorable tidal lands" to promote long-term conservation
• "Manage, restore, and monitor" tidal marsh habitat
• Conduct range-wide species status surveys/monitoring and status reviews in these areas
• Conduct research necessary for the recovery of the species in these habitats and the long-term conservation of these species
• Improve coordination, participation, and outreach activities to achieve recovery of listed species and long-term conservation of species of concern

Estimated Cost of Recovery:
Grand Total: $1,242,501,640, plus "costs that are unable to be determined at this time"

The plan is expected to be complete by 2063 (50 years from the most recent update of the recovery plan)

Works Consulted http://ecos.fws.gov/docs/recovery_plan/TMRP/20130923_TMRP_Books_Signed_FINAL.pdf

http://en.wikipedia.org/wiki/Salt_marsh_harvest_mouse#Conservation

http://web.archive.org/web/20100116090555/http://bss.sfsu.edu/holzman/courses/Spring%2005%20projects/SMH%20mouse/salt_marsh_harvest_mouse%202.htm


Photo 1: http://www.mnh.si.edu/mna/images/images/salt-marsh_harvest_mouse_thumb.jpg
Photo 2: http://gallery.usgs.gov/images/05_17_2013/mQHt3XWjj1_05_17_2013/large/SMHM.jpg
Photo 3: http://upload.wikimedia.org/wikipedia/commons/thumb/5/5c/BayareaUSGS.jpg/220px-BayareaUSGS.jpg
GIF: http://giphy.com/gifs/harvest-mouse-60NrFxmeeSCoE