Save
this Mouse’s House!
Salt
Marsh Harvest Mouse (Reithrodontomys
raviventris)
By:
Regan Dyer
http://www.fws.gov/uploadedImages/Region_8/NWRS/Zone_2/San_Francisco_Bay_Complex/San_Pablo_Bay/Images/Wildlife_and_Habitat/B.Moose.Peterson_520.jpg
Description and
ecology of organism:
 |
|
http://virtualmarsh.org/wp-content/uploads/2012/02/
Salt-Marsh-Harvest-Mouse-e1330123104435.jpg
|
The salt marsh harvest mouse, also known as the “red-bellied harvest mouse, makes its home in the Bay Area of Northern California. Like its name implies, this mouse loves to live in the marshes of Corte Madera, Richmond and South San Francisco. There are two subspecies, the northern and the southern, and each have their own specific colorings. The southern has a cinnamon colored belly while the northern does not. The rest of their bodies are buff or brown and they have darker colored ears. While their coloring may differ, both have grooved upper front teeth that help them eat leaves, seeds and plant stems. Both subspecies can drink salt water for long periods of time, with the southern actually preferring salty water over fresh water. The mice are about 3 inches long and weigh only half an ounce.
Females give birth one or two times a year with an average
litter size of four. Their nests are minimal (the southern doesn’t actually
build a nest) and are often built on top of abandoned bird nests. The average
home range size for the salt marsh harvest mouse is 0.52 acres
Geographic and
Population Changes:
 |
| http://www.audublog.org/blog/wp-content/ uploads/2008/09/sanpablo1.jpg |
The salt marsh harvest mouse lives in Don Edwards San Francisco Bay National Wildlife Refuge and the San Pablo Bay National Wildlife Refuge. These areas offer dense cover for the salt mouse thanks to high populations of salt-tolerant plants like pickleweed. These plants allow the mice to climb above high tides.
Both species have
experienced high levels of habitat loss and fragmentation as the human
population in the area has grown. Less than 10% of the original acreage of the
specie’s habitat is left, with that limited area retaining little to no
structural suitability for the mouse. Over 600 acres of salt marsh in the
mouse’s habitats has been converted to fresh or brackish water due to
freshwater discharge from many wastewater facilities throughout the area.
Listing Date and Type
of Listing:
Endangered
Listed 10-13-1970
Lead Region: California/Nevada Region (Region 8)
Cause of Listing and Main Threats to its Continued Existence:
 |
|
http://farm9.staticflickr.com/8172/
8049449401_e0ee13c7c2_z.jpg
|
The mouse is battling severe habitat loss. Much of its marsh habitat has disappeared due to filling and vegetation changes. “Of the 193, 800 acres of tidal marsh that bordered San Francisco Bay in 1850, about 30,100 remain. This represents an 84 percent reduction”. This loss of habitat is truly the main cause for the listing of the species. The mouse is specialized for its environment and is greatly impacted when its small/specific habitat decreases in size.
Besides infill and water salinity
changes, another factor is that many marshes are completely submerged at high
tide, especially in the south Bay. When the water level goes above the weedy
grasses, the mice run out of climbing space and can’t escape the water. The
complete submerging also leads to nest destruction and higher levels of
predation, as the mice can no longer hide in vegetation. Hawks, gulls, and
short-eared owls are typical predators for the mice. Herons, egrets, and
kestrels are also known to take small mammals from flooded marsh areas.
Terrestrial predators such as foxes, feral cats, skunks, and raccoons may also
have an impact on the population.
Primary threats to all the
listed species include:
- Habitat loss and fragmentation due to urban
development, agriculture, and diking related to duck hunting
- Changes in hydrology and water salinity
- Non-native invasive species
- Contamination
- Sea level rise due to climate change
- Overall vulnerability of small population that is
endemic to an area
Description of
Recovery Plan:
The recovery plan encompasses 5 species and 11 subspecies
that live in the tidal marsh ecosystem; for example, the salt marsh harvest
mouse, California clapper rail, Suisan thistle, soft bird’s beak, and the
California sea-blithe.
 |
|
http://ucdavis.edu/local_resources/slideshow/2014/April/
marsh-mice/09-released.jpg
|
The U. S. Fish and
Wildlife Service requires that within a 50-year planning period the objectives
listed below will be realized:
1.
Secure
self-sustaining wild populations of each covered species throughout their full
ecological, geographical, and genetic ranges.
2.
Ameliorate
or eliminate the threats, to the extent possible, that caused the species to be
listed or of concern and any future threats.
3.
Restore and conserve a healthy ecosystem
function supportive of tidal marsh species.
They hope to
acquire, manage, monitor and restore the historic, existing, and restorable
marsh habitat of the mouse and other species. They also want to conduct
research and surveys on the species to observe the status of the population. The
overall goal is to achieve recovery of the mice.If the program goes as planned and recovery criteria are met, the U.S Fish and Wildlife Service estimates that most of the listed species in this recovery plan could be recovered by 2063 (that’s only 50 years!).
Sources:
Department of the Interior: Fish and Wildlife Service.
Final
Recovery Plan for Tidal Marsh Ecosystems of Northern and Central California
Fish and Wildlife Service
Recovery
Plan for Tidal marsh Ecosystems of Northern and Central California
http://ecos.fws.gov/docs/recovery_plan/TMRP/Appendices%20for%20Recovery
%20Plan%20for%20Tidal%20Marsh.pdf
%20Plan%20for%20Tidal%20Marsh.pdf
U.S. Environmental
Protection Agency:
Endangered Species Protection
Program (ESPP) : Endangered Species Fact Sheet
Coastal
Conservancy: San Francisco Estuary Invasive Spartina Project
|
|
No comments:
Post a Comment