(DRAFT) - Taxonomy
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
TAXONOMY
NAME - MOUSE, HARVEST, SALT MARSH
OTHER COMMON NAMES - MOUSE, HARVEST, SALT MARSH; MOUSE, HARVEST and SALT-MARSH
ELEMENT CODE -
CATEGORY - Mammals
PHYLUM AND SUBPHYLUM - CHORDATA,
CLASS AND SUBCLASS - MAMMALIA,
ORDER AND SUBORDER - RODENTIA,
FAMILY AND SUBFAMILY - MURIDAE,
GENUS AND SUBGENUS - REITHRODONTOMYS,
SPECIES AND SSP - RAVIVENTRIS,
SCIENTIFIC NAME - REITHRODONTOMYS RAVIVENTRIS
AUTHORITY -
TAXONOMY REFERENCES -
COMMENTS ON TAXONOMY -
Salt Marsh Harvest Mouse
Reithrodontomys raviventris Dixon, 1908
KINGDOM: Animal GROUP: Mammal
PHYLUM: Chordata CLASS: Mammalia
ORDER: Rodentia FAMILY: Muridae
Two subspecies of Reithrodontomys raviventris are recognized
(01). They are R. r. halicoetes found in the marshes of northern and
central San Francisco Bay and R. r. raviventris found in the central
and southern San Francisco Bay and on the southern portion of the
Marin Peninsula. Reithrodontomys r. halicoetes was originally
described as R. halicoetes and R. r. raviventris as R. raviventris by
Dixon (02,03).
Externally both subspecies are similar in appearance to R.
megalotis longicaudus (western harvest mouse) in the San Francisco Bay
region. The length of the tail is longest in Suisun Bay populations
and shortest in Santa Clara populations, and tail/body ratios are
useful in diagnosis in these two areas. The thickness of the tail at
20 mm from the body is the most useful feature in identification as R.
raviventris has a thicker tail (2.1 to 3.0 mm) than R. megalotis
(generally 1.9 to 2.0 mm). The tip of the tail is blunt and the tail
Taxonomy - 1 (DRAFT) - Taxonomy
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
is unicolor or nearly so. No white hairs are found on the underside
of the tail in typical salt marsh harvest mice, although considerable
variation exists. The pelage is usually darker and the venters of
individuals of R. r. raviventris are usually cinnamon-colored. There
is clinal variation of the venter. Most individuals of R. r.
halicoetes and northern populations of R. r. raviventris have white
venters, even whiter than those of R. megalotis but the percentage of
individuals with darker bellies increase towards the southern end of
the species' range. For a complete discussion of the morphological
differences between these mice see Fisler, 1965 (04).
Only two characteristics of the cranium are known to be
diagnostic. Reithrodontomys raviventris has a significantly longer
length of brain case (04) and a relatively and significantly shorter
distance between the anterior end of the palatine foramen and the
posterior end of the incisive foramen as compared with the length of
the palate from the latter point to its posterior end (05). The
phallus, the simple, slightly-curved baculum and the vagina of R.
raviventris are significantly shorter than those of R. megalotis (04).
The baculum does not exhibit diagnostic differences.
Some ranges of measurements (in mm) from Fisler (04) are:
Total length, 118 to 175;
Length of tail, 56 to 95;
Hindfoot, 15 to 21;
Length of skull, 19.5 to 22.4;
Depth of brain case, 6.1 to 7.6;
Width of intermeatus, 6.7 to 8.5;
Breadth of brain case, 9.2 to 11.0;
Length of rostrum, 8.9 to 10.9;
Length of brain case, 9.5 to 10.9;
Length of nasal, 6.5 to 8.5;
Length of incisive foramen, 3.7 to 4.5; and
Weight, 7.6 to 14.5 grams.
The upper parts of R. r. raviventris are blackish and cinnamon.
A lateral line is present as a tawny stripe. The venter varies from
white to cinnamon. The upper parts of R. r. halicoetes are lighter
than R. r. raviventris but darker than R. megalotis. A lateral line
is seldom present and the venter is usually white. The ears of both
subspecies are dark; those of R. r. raviventris blackish. Most salt
marsh harvest mice have tuffs of ochraceous hairs at the anterior
bases of their ears. The pelage of salt marsh harvest mice is longer
and thicker than that of R. megalotis at all seasons.
The tails of salt marsh harvest mice are indistinctly bicolored.
There are always brownish hairs on the under surface, something absent
from the bicolored tail of R. megalotis.
A topotype from Palo Alto, Santa Clara County, CA is deposited at
MVZ No. 3527. Descriptions of the animal can be found in references
04, 05, and 07. A drawing and photographs can be found in reference
08.
A variation in the common name spelling is salt-marsh harvest
mouse (14).
Taxonomy - 2 (DRAFT) - Status
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
STATUS
Coded Status
E: Federal Endangered
COMMENTS ON STATUS -
The salt marsh harvest mouse (Reithrodontomys raviventris) has
been designated an Endangered species pursuant to the Endangered
Species Act of 1973 (50 CFR 17.11; P.L. 93-205, 87 Stat. 884;
16 U.S.C. 1531-1540), as amended. The species has this status
wherever found including the State of California. Critical Habitat
has not been designated.
This species is protected by the Lacey Act (P.L. 97-79, as
amended; 16 U.S.C. 3371 et seq.) which makes it unlawful to import,
export, transport, sell, receive, acquire, or purchase any wild animal
(alive or dead including parts, products, eggs, or offspring):
(1) in interstate or foreign commerce if taken, possessed,
transported or sold in violation of any State law or
regulation; or
(2) if taken or possessed in violation of any U.S. law,
treaty, or regulation or in violation of Indian tribal law.
It is also unlawful to possess any wild animal (alive or dead
including parts, products, eggs, and offspring) within the U.S.
territorial or special maritime jurisdiction (as defined in
18 U.S.C. 7) that is taken, possessed, transported, or sold in
violation of any State law or regulation, foreign law, or Indian
tribal law.
RESPONSIBLE FEDERAL AGENCIES:
USFWS -Responsible for the management/recovery, listing, and
law enforcement/protection of this species.
DOD -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public land under their control. Also responsible for
management/recovery on Department of Defense lands.
All Federal agencies have responsibility to ensure that any
action authorized, funded, or carried out by that agency is not likely
to jeopardize the continued existence of the species or result in the
destruction or adverse modification of Critical Habitat (50 CFR 402),
and to utilize their authorities to carry out programs for the
conservation of the species.
STATE STATUSES AND LAWS:
STATE: California
Status - 1 (DRAFT) - Status
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
DESIGNATED STATUS: Endangered
ADMINISTRATIVE AGENCY: California Department of Fish and Game
STATE STATUTE: California Endangered Species Act; Fish and Game
Code, Ch. 1.5, Art. 1, Sec. 2050.
INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
Reithrodontomys raviventris is listed as Endangered in the IUCN
Red Data Book Part I (1982). This species is also listed by the
U.S. in the Convention on Nature Protection and Wildlife POreservation
in the Western Hemisphere Annex, 1970.
ECONOMIC STATUSES:
The salt marsh harvest mouse has attracted much interest from the
public and media. The mouse has come to represent conservation in the
battle to protect wetland habitats from development.
70/08/25:35 FR 13519/13520 - Proposed rule
70/10/13:35 FR 16047/16048 - Listed as Endangered
79/05/21:44 FR 29566/29577 - Five year review
85/07/22:50 FR 29901/29909 - Five year review
Status - 2 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
COASTAL
LAND USE -
Residential
Industrial
Transportation, communications, and Util
Mixed Urban or Built-up Land
Streams and Canals
Bays and Estuaries
Nonforested Wetland
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Estuarine, intertidal EM6
Estuarine, intertidal EM4
COMMENTS ON HABITAT ASSOCIATIONS -
Salt marsh harvest mice use pickleweed (Salicornia virginica) as
their primary habitat as long as they have non-submerged,
salt-tolerant vegetation for escape during the highest tides. The
value of pickleweed increases with depth, density and the degree of
intermixing with fat hen (Atriplex patula) and alkali heath (Frankenia
grandifolia). Salt grass may be valuable in such mixtures but has
little value as a pure stand. Alkali bulrush (Scripus robustus) has
little habitat value either in tidal or diked situations. Other
species used where they occur in relatively pure patches include the
annual fat hen and perennial Australian saltbush (A. semibaccata).
Recent studies have found mice at a variety of locations in ruderal or
disturbed habitats with a relatively low species composition of
pickleweed (19). Plant species diversity, including facultative and
upland species intermixed with wetland plants, is often quite high in
these situations.
The characteristics, then, of preferred habitat for salt marsh
harvest mice are as follows:
(1) Areas should have 100% cover;
(2) Vegetation depth of 30-50 cm at summer maximum;
(3) A high percentage of pickleweed present. Areas conducive to
denser populations of harvest mice range from 100% pickleweed to 50
pct. w/ a variety of other halophytes, especially fat hen and alkali
heath. Scirpus and Typha species do not reduce the quality of such
habitat so long as they are not present in pure stands.
(4) No areas, or very few and small areas, of salt grass
(Distichlis spicata), brass buttons (Cotula coronopifolia), alkali
bulrush, other Scripus species or Typha. Upland grasses are valuable
as an upland edge but not as a dominant within the marsh;
(5) No barriers of open ground or water dissecting the
vegetation.
(6) Large marsh areas. Connections between marsh areas should be
a minimum of 20 m wide with 100 percent cover of optimal vegetation
with no barriers of open ground or water across them. Most of marsh
should be habitable throughout the year. The nature of the soil
surface and the management practices should result in at least 40
percent of the marsh being usuable in the winter (i.e., receiving
little, if any, flooding). A majority of the marsh (80 percent or
more) should be of optimum habitat in the summer. Each marsh should
Habitat Associations - 1 have a large edge of halophytes and an adjoining and interdigitating
band of transitional vegetation, including grasses;
(7) Areas should receive minimal disruptive manipulation and only
that needed to provide and maintain mouse habitat. Seasonal inputs of
freshwater in diked marshes may stimulate growth by halophtes but
should not be so great as to shift vegetative dominance to fresh and
brackish species. Plowing, mowing and/or burning of such areas should
not be allowed.
The species occurs on various islands with suitable habitat in
the San Francisco Bay area. The species occurs near or adjacent to
highways, urban industrial and residential lands, aqueducts and flood
control channels. Disturbances in these areas could adversely impact
the mouse. Therefore, buffer spaces in the form of transitional
wetlands/uplands should be provided.
Habitat Associations - 2 (DRAFT) - Food Habits
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
FOOD HABITS
TROPHIC LEVEL -
HERBIVORE
LIFESTAGE FOOD FOOD PART
General Vascular Plants-Emergent Nonwoody
General Poaceae
General
Food Habits - 1 (DRAFT) - Environment Associations
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Coastal Features: Vegetated offshore islands
Environment Associations - 1 (DRAFT) - Life History
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
LIFE HISTORY
FOOD HABITS:
Fisler (04) noted that salt marsh harvest mice eat green
vegetation including grasses, in addition to seeds. They have longer
intestines than the western harvest mouse, which is a seed eater. The
northern subspecies can drink sea water for long periods of time but
prefers to drink freshwater. The southern subspecies is unable to
drink sea water as its only drinking fluid but prefers moderately
saline water (04). The effect of salinity on the diet of these mice
is only partially understood (13,14,15) but may be a critical factor
in their management. Little else is known about the food or drinking
habits of this species. No work has been done since that of Fisler
(04,13) and since the species has been declared endangered.
HOME RANGE/TERRITORY:
This species is probably not territorial. There have been few
studies of home range and then only in very narrow, elongated marshes
(11). Rice found that mice living in one such narrow marsh north of
Alviso had home ranges that varied from 20 to 300 meters by 5 meters
wide, 100 square meters to 1,500 square meters. Most of her animals
apparently lived in home ranges of from 100 to 150 square meters;
similar results have been observed in the personal trapping of H.
Shellhammer (19). Little is known about the size or configuration of
home ranges in the few marshes in which there is adequate cover in a
second dimension.
PERIODICITY:
Both subspecies are essentially nocturnal becoming active 1/2 to
1 1/2 hours after sunset and becoming inactive just before sunrise
(04).
MIGRATION PATTERNS:
Although not well understood, seasonal shifts in habitat
selection and dispersion to or colonization of new habitats may occur
while opportunities exist. They may swim between marshes during
exceptionally high tides or storm-driven high tides (04) but it is not
known whether this activity is common.
Fisler (04,16) noted that salt marsh harvest mice will move up
into the grasslands bordering marshes during spring and summer when
the grasslands provide maximum cover. This sort of movement is less
common in that most of the marshes in the range now lack such a
grassland edge (06,10).
Fisler (04,16) also reported that the mice move deeper into the
marshes as the tidal cycles expose more of the marshes.
COVER/SHELTER REQUIREMENTS:
These animals are extremely cover-dependent (04,07,08,10,11,12).
Neither subspecies, however, burrow (04). Individuals of R. r.
halicoetes build ball-like nests quite like those of western harvest
mice. These balls of dry grasses and/or sedges are usually placed on
the ground surface and probably are rebuilt quickly when wetted by the
waters of high tides (04). R. r. raviventris apparently does little
Life History - 1 (DRAFT) - Life History
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
nest building. Shellhammer (20) noted loosely organized nests of dry
grasses built on the ground, whereas Fisler (04) saw no mouse nests
that he could associate with certainty with this subspecies. Johnston
(17) reported that these mice roofed over at least five old nests of
song sparrows. Vegetative cover is a necessity.
The characteristics of preferred habitat for salt marsh harvest
mice are as follows:
(1) Areas should have 100% cover;
(2) Vegetation depth of 30-50 cm at summer maximum;
(3) A high percentage of pickleweed present. Areas conducive to
denser populations of harvest mice range from 100% pickleweed to 50
pct. w/ a variety of other halophytes, especially fat hen and alkali
heath. Scirpus and Typha species do not reduce the quality of such
habitat so long as they are not present in pure stands.
(4) No areas, or very few and small areas, of salt grass
(Distichlis spicata), brass buttons (Cotula coronopifolia), alkali
bulrush, other Scripus species or Typha. Upland grasses are valuable
as an upland edge but not as a dominant within the marsh;
(5) No barriers of open ground or water dissecting the
vegetation.
(6) Large marsh areas. Connections between marsh areas should be
a minimum of 20 m wide with 100 percent cover of optimal vegetation
with no barriers of open ground or water across them. Most of marsh
should be habitable throughout the year. The nature of the soil
surface and the management practices should result in at least 40
percent of the marsh being usuable in the winter (i.e., receiving
little, if any, flooding). A majority of the marsh (80 percent or
more) should be of optimum habitat in the summer. Each marsh should
have a large edge of halophytes and an adjoining and interdigitating
band of transitional vegetation, including grasses;
(7) Areas should receive minimal disruptive manipulation and only
that needed to provide and maintain mouse habitat. Seasonal inputs of
freshwater in diked marshes may stimulate growth by halophtes but
should not be so great as to shift vegetative dominance to fresh and
brackish species. Plowing, mowing and/or burning of such areas should
not be allowed.
REPRODUCTIVE SITE REQUIREMENTS:
Nothing is known about this subject for this species.
REPRODUCTIVE CHARACTERISTICS:
Fisler (04) believed that R. r. halicoetes males were not very
active reproductively in December and January, and that males of R. r.
raviventris were probably inactive from November through January.
Males of R. r. halicoetes are sexually active from April through
September, whereas most breeding by females was from March through
November. The breeding season for R. r. raviventris was shorter,
apparently May through November. Fisler (04) noted that R. r.
halicoetes had an average litter size of 3.7 to 3.9; R. r. raviventris
had an average of 4.0 although the latter figure was based on a sample
of only 14 litters.
PARENTAL CARE:
Life History - 2 (DRAFT) - Life History
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
Nothing is known.
POPULATION BIOLOGY:
It is not known whether food supply, disease or almost any other
factor is limiting. Marsh areas without appropriate cover lack mice;
so do narrow marshes without refugial zones into which the mice can
escape during flooding or high tides. Flat, shallow marshes usually
lack mice even when nearby and connected areas with better refugia
(i.e., peripheral halophyte zones) do support mice (06,10,19).
Vegetation change may be limiting; changes from pickleweed to alkali
bulrush usually results in the disappearance of mice.
Densities are difficult to estimate. Most marshes can only be
trapped by single, long lines of live traps placed 10 meters apart.
Hence relative comparisons are made through the use of trapping
effort. Summer trapping success rates typically vary from
approximately 50 trap nights (TN) per mouse to more than 350 TN/mouse.
Many marginal marshes may not yield mice in two out of tree trapping
efforts spread over several years.
Average litter size is between 3.7 and 4.0 and probably most
animals have only one litter per year (04). Average life span is a
year or less, hence the biotic potential is not high. Population
densities are correlated with cover depth and quality (10) hence
management objectives should include the production of large areas of
optimum habitat (18).
SPECIES INTERRELATIONSHIPS:
The quality of pickleweed (Salicornia virginica) is directly
correlated with the number of salt marsh harvest mice an area can
produce. Full (100%) cover of pickleweed 30 to 50 cm deep is optimal,
especially if there are other halophytes intermixed (04,06,07,08,10,
18). Refugial vegetation, especially that composed of peripheral
halophytes, is necessary in tidal marshes and in diked marshes which
flood seasonally (10).
Although not well-studied, competitive interference within the
small mammal community, such as with rats, house mice, voles and
western harvest mice, may limit the distribution of the species to
varying degrees in marshes throughout its range.
Predators such as raptorial birds may put increased predation
pressure on the mice due to man's modification of tidal and non-tidal
areas. At high tides the mice have less refugia than in the past, and
the concentration of mice in these areas may make them more vulnerable
to predation (20). Feral cats and other mammalian predators also
appear to pose a threat to the species, especially during periods of
high water when escape cover is lacking.
OTHER LIFE HISTORY DESCRIPTORS:
Salt marsh harvest mice are relatively calm as compared to the
nervousness or tenseness of western harvest mice (04,07,18). The
latter species acts like the house mouse, Mus musculus, in that it is
very active, bites a lot and jumps from traps without hesitation.
Salt marsh harvest mice tend to be placid, bite relatively little,
remain balled up in the cotton of traps, and are more deliberate in
their movements. So typical are the behaviors of these two species
Life History - 3 (DRAFT) - Life History
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
that behavior is used as a secondary diagnostic feature in the field
(05).
Individuals of both subspecies swim calmly and well. Their
bouyant fur does not wet nearly as quickly as that of western harvest
mice (04).
Life History - 4 (DRAFT) - Management Practices
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Adverse Developing/maintaining stream bank vegetation
Adverse Dredging
Adverse Flooding
Adverse Groundwater drawdown
Adverse Low Gene Pool
Adverse Predation
Adverse Rural Residential/Industrial Areas
Adverse Salinity alteration
Adverse Shoreline modification/development
Adverse Water Level Fluctuation
Adverse Draining wetlands, marshes, ponds, lakes
Beneficial Controlling/Removing Nonnative Vegetation
Beneficial Controlling/Restricting Pesticide Use
Beneficial Controlling pollution [thermal, chemical, physical]
Beneficial Creating Artificial Habitat/Nesting Structure
Beneficial Reforestation
Beneficial Maintaining/Controlling Water Flow
Beneficial Developing/maintaining/protecting wetlands
Beneficial Maintaining undisturbed/undeveloped areas
Beneficial Suppressing wildfire
Beneficial Land Acquisition
Beneficial Restricting/regulating human disturbance of populations
Beneficial
Beneficial Reducing Urban Light Radiation
Beneficial Transplanting wild animals
Existing Developing/maintaining stream bank vegetation
Existing Dredging
Existing Flooding
Existing Groundwater drawdown
Existing Low Gene Pool
Existing Predation
Existing Rural Residential/Industrial Areas
Existing Salinity alteration
Existing Shoreline modification/development
Existing Water Level Fluctuation
Existing Draining wetlands, marshes, ponds, lakes
COMMENTS ON MANAGEMENT PRACTICES -
Shellhammer (06,07) enumerated the major threats to the habitat
of salt marsh harvest mice which included filling, diking, subsidence
and changes in salinity. A few marshes, such as the one on the
northern edge of San Pablo Bay, are growing because of increased
sedimentation at their bayward edges. Most marshes studied by Fisler
(04) in the late 1950's and early 1960's, however, have been reduced
in size or quality since then, or have been destroyed. Loss of
habitat has been greatest in the range of R. r. raviventris.
Wondollenck et al. (08) studied the Palo Alto salt marsh and noted
that the Spartina-dominated portions of the marsh had increased from
Management Practices - 1 (DRAFT) - Management Practices
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
the 10% of the marsh noted by Hinde (09) to 70%; Spartina is avoided
by salt marsh harvest mice. Concurrently the Salicornia areas have
decreased from 90% to less than 10% and the mice are concentrated in
this small area. The Palo Alto-Alviso area has undergone condiserable
subsidence which has induced the changes in vegetation at Palo Alto
and throughout the Alviso marshes. Decreased salinities in the Alviso
area of southern San Francisco Bay, due to increasing volumes of
non-saline, treated sewage water, is changing the major Salicornia
marshes to nearly uniform Scirpus robustus marshes, another type of
vegetation little used by the mice (10).
Diking and filling for residential industrial development have
destroyed most of the marshes of the San Francisco Bay area and most
of the transition areas bordering those marshes that remain. These
impacts are especially severe in the southern San Francisco Bay. What
transitional vegetation that remains is dominated by peripheral
halophytes, which include the introduced Atriplex sembaccata; these
areas are used heavily as upland refugia during certain times of the
year and various phases of tidal cycles (10,11,12). Throughout most
of the San Francisco Bay area, and especially in the subsided areas of
the southern San Francisco Bay, the usuable portions of former marshes
have been reduced to narrow strips along dikes.
Recent studies (21) have documented the species in a variety of
non-tidal wetlands. Although pickleweed is usually the dominant
species, a diverse assemblage of fresh, brackish and transitional
vegetation is commonly present.
Hence today most marshes are small and separated from one
another; movement between marshes is minimal or lacking and genetic
stagnation is a possibility in many marshes. Many marshes are
strip-like and have very little usuable areas of the most preferred
vegetation, that of Salicornia. Few marshes have adequate peripheral
halophyte zones; such marshes soon lose their mice if they are tidal
marshes as animals are forced into the open and are preyed upon or
drown. Many tidal marshes are undergoing vegetation changes due to
changes in salinity or sedimentation rates. Other marshes are
changing to little used vegetation because of subsidence and
subsequent increased tidal coverage.
Future perceived threats include all of the above plus the
multiple effects of development. Filling of tidal marshes and diked
marshes destroy habitat and at the same time increase the value of
other marsh lands for future development. High land costs result in
very small mitigation packages for the dollars spent on mitigation.
The result will be more small marshes separated at great distances
from one another. Large marshes are needed to preserve individual
populations over time; few large marshes are being saved.
Landward development is encroaching on many marshes. Peripheral
halophyte zones are being destroyed. Human foot and vehicle traffic
increasingly impact such marshes and lead to the destruction of needed
vegetation. Water pollution has not been identified as a problem as
yet; it may become one, however, especially in the southern San
Francisco Bay with its high degree of commercial and residential
development surrounding the Bay.
Management Practices - 2 (DRAFT) - Management Practices
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
APPROVED PLAN:
U.S. Fish and Wildlife Service. 1984. Salt Marsh Harvest Mouse and
California Clapper Rail Recovery Plan. U.S. Fish and Wildlife
Service, Portland, OR. 141 pp.
Recovery actions for the salt marsh harvest mouse are included
in the Salt Marsh Harvest Mouse and California Clapper Rail Recovery
Plan. The primary objective of the recovery plan is (1) to secure
and manage 3900 hectares of essential habitat under government
jurisdictions, (2) to secure and manage 3200 hectares of habitat which
is mostly privately owned and (3) to restore and/or enhance 7000
hectares of historic habitat. The completion of the foregoing would
allow the northern subspecies of mouse to be upgraded to Threatened
with consideration for delisting, and the southern subspecies of mouse
and the rail population to be upgraded to Threatened. Delisting of
the rail and southern subspecies of mouse may be possible following
completion of the above, plus restoration and/or enhancement of an as
yet undetermined amount of additional habitat (currently estimated at
about 3,000 hectares).
The following actions are needed to meet the recovery criteria
listed above:
1. Existing marshes must be protected, and marshes should be
interconnected or combined in order to create maximum populations.
2. Habitat management plans need to be developed and implemented on
all marshes. These plans may include removal of exotic vegetation;
planting native plant species in the upper marsh; restricting land
filling, plowing, mowing and burning; minimizing or preventing
freshwater flushing; limiting human access to upper marsh areas;
diking in some areas; restoring tidal action; and eliminating or
reducing pesticides (e.g., for mosquito control or agriculture) and
pollution.
3. Unprotected marshes and essential marshes need to be secured and
managed to allow the restoration, enhancement, or creation of habitat
rich in pickleweed. Habitat may be secured and protected from
development through land acquisition, cooperative agreement or other
means.
4. Upper portions of marshes must be restored to provide refugia
during high tides and to provide nesting habitat in marshes which have
undergone subsidence and vegetational changes. In some instances this
may involve creating islands or peninsulas of high ground for refugia.
5. Biological research on impacts from sewage effluents, pollutants,
flood control measures, salinity, mosquito abatement, rise in sea
level, reduced sedimentation, marsh erosion, and marsh accretion is
needed to provide information essential to recovery efforts.
6. Reestablish populations at selected locations through
translocation of wild individuals.
Management Practices - 3 (DRAFT) - Management Practices
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
7. Development and implementation of a program for conservation
education.
Management Practices - 4 (DRAFT) - References
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
References
***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****
01 Howell, A.H. 1914. Revision of the American harvest mice. N. Am.
Fauna 36:1-97.
02 Dixon, J. 1909. A new harvest mouse from Petaluma, California.
Univ. Calif. Publ. Zool. 5:271-273.
03 Dixon, J. 1908. A new harvest mouse from the salt marshes of San
Francisco Bay, California. Proc. Biol. Soc. Wash. 21:197-198.
04 Fisler, G.F. 1965. Adaptations and speciation in harvest mice of
the marshes of San Francisco Bay. Univ. Calif. Publ. Zool.
77:1-108.
05 Shellhammer, H.S. 1984. Identification of salt marsh harvest
mice, Reithrodontomys raviventris, in the field and with cranial
characteristics. Calif. Fish and Game 70:113-120.
06 Shellhammer, H.S. 1977. Of mice and marshes. San Jose Studies,
San Jose St. Univ. 3:23-35.
07 Shellhammer, H.S. 1982. Reithrodontomys raviventris. Mammalian
Species, Amer. Soc. Mammal. No. 169:1-3.
08 Wondolleck, J.T., W. Zolan, and G.L. Stevens. 1976. A population
study of harvest mice in the Palo Alto salt marsh. Wasmann J.
Biol. 34:52-64.
09 Hinde, H.P. 1954. Vertical distribution and salt marsh
phanerograms in relation to tide levels. Ecol. Monogr. 24:209-225.
10 Shellhammer, H.S., R. Jackson, W. Davilla, A. Gilroy, H.T. Harvey,
and L. Simons. 1982. Habitat preferences of salt marsh harvest
mice (Reithrodontomys raviventris). Wasmann J. Biol.
40(1-2):102-114.
11 Rice, V. [n.d.] The population ecology of salt marsh harvest mice
at triangular marshes. M.A. Thesis, San Jose St. Univ., San Jose,
CA.
12 Zetterquist, D. 1978. The salt marsh harvest mouse
(Reithrodontomys raviventris raviventris) in marginal habitats.
Wasmann J. Biol. 35:68-76.
13 Fisler, G.F. 1963. Effects of salt water on food and water
consumption and weight of harvest mice. Ecology 44:604-608.
14 Haines, H. 1964. Salt tolerance and water requirements in the
salt-marsh harvest mouse. Physiol. Zool. 37:266-272.
15 Coulombe, H.N. 1970. The role of succulent halophytes in the
water balance of salt marsh rodents. Oecologia 4:223-274.
16 Fisler, G.F. 1968. Adaptations in movement patterns of two
species of salt marsh rodents. Bull. So. CA Acad. Sci. 67:96-113.
17 Johnston, R.F. 1956. Predation by short-eared owls in a
Salicornia salt marsh. Wilson Bull. 68:91-102.
18 U.S. Fish and Wildlife Service. 1984. Salt Marsh Harvest Mouse
and California Clapper Rail Recovery Plan. U.S. Fish and Wildlife
Service, Porland, OR. 141 pp.
19 Shellhammer, H.S. 1975-1985. Personal trapping records. Dept.
Biological Sciences, San Jose St. Univ., 1 Washington Square, San
Jose, CA 95192.
20 Shellhammer, H.S. 1985. Personal observations. Dept. Biological
Sciences, San Jose St. Univ., 1 Washington Square, San Jose, CA
References - 1 (DRAFT) - References
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
95192.
21 California Department of Fish and Game. [n.d.] Unpubl. data. on
file at: Sacramento Endangered Species Office, Sacramento, CA.
***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****
01 Fisler, G.F. 1965. Adaptations and speciation in harvest mice of
the marshes of San Francisco Bay. Univ. CA Publ. Zool. 77:1-108.
02 U.S. Fish and Wildlife Service. 1984. Salt Marsh Harvest Mouse
and California Clapper Rail Recovery Plan. U.S. Fish and Wildlife
Service, Portland, OR. 141 pp.
03 Jones and Stokes Assoc., Harvey and Stanley Assoc., and John Blaney
Assoc. 1979. Protection and restoration of San Francisco Bay fish
and wildlife habitat. CA Dept. Fish Game and U.S. Fish & Wildl.
Serv., Sacramento, CA.
04 Shellhammer, H.S., R. Jackson, W. Davilla, A. Gilroy, H.T. Harvey,
and L. Simons. 1982. Habitat preferences of salt marsh harvest
mice (Reithrodontomys raviventris). Wasmann J. Biol.
40(1-2):102-114.
05 Simons, L. and H.S. Shellhammer. Trapping survey of salt marsh
harvest mice Reithrodontomys raviventris halicoetes during the
summer of 1980. Calif. Dept. Fish Game, Nongame wild. Invest.
Final Rept. E-W-4, V-3.1.
06 Newcomer, M. 1982. Trapping survey of salt marsh harvest mice,
Reithrodontomys raviventris, in the marshes of the San Francisco
Bay region during 1982. San Fran. Bay NWR, Newark, CA.
07 Harvey and Stanley Assoc. 1984. Bahia Property salt marsh harvest
mouse (Reithrodontomys raviventris) trapping program. 17 pp.
08 Botti, Fred. 1984. Personal communication. California Department
of Fish and Game, P.O. Box 47, Yountville, CA.
09 Shellhammer, H.S. Personal trapping records, various times in
1960's and 1970's. Department of Biological Sciences, San Jose
State University, 1 Washington Square, San Jose, CA 95192
10 Harvey and Stanley Associates. 1980. Status of the salt marsh
harvest mouse (Reithrodontomys raviventris) in the Suisun Marsh.
Water and Power Resour. Serv., Sacramento, CA.
11 Botti, F. May 1981. Personal communication. California
Department of Fish and Game, Yountville, CA.
12 Envirodyne Engineers. 1978. Salt marsh harvest mouse trapping and
vegetative study at the Montezuma Powerplant Site. Pacific Gas and
Electric.
13 Biosystems Analysis. 1978. Potential for mitigation of salt marsh
losses and associated impacts on salt marsh harvest mice at the
proposed Montezuma Powerplant Site. Pacific Gas and Electric.
14 Biosystems Analysis. 1979. Technical report on the 1979 summer
trapping program for the endangered salt marsh harvest mouse at the
Montezuma Powerplant Site. Pacific Gas and Electric.
15 Biosystems Analysis. 1980. Winter salt marsh harvest mouse
trapping results and spring vegetation survey, 1979-1980.
Technical Report, Pacific Gas and Electric.
16 Biosystems Analysis. 1980. Technical report on the 1980 summer
trapping program for the endangered salt marsh harvest mouse at the
References - 2 (DRAFT) - References
Species MOUSE, HARVEST, SALT MARSH
Species Id ESIS051004
Date 14 MAR 96
Montezuma Powerplant Site. Pacific Gas and Electric.
17 Western Ecological Service Company. 1981. Personal communication.
WESCO work done for Pacific Gas and Electric, 1978-1979.
18 Harvey and Stanley Associates. July 30, 1979. Memorandum, Concord
Naval Weapons Station, Department of the Navy.
19 Harvey and Stanley Associates for EDAW. July 29, 1980. Salt marsh
harvest mouse survey, Stockton Ship Channel Sites, Contra Costa
County, CA.
20 Harvey and Stanley Associates for ESA Madrone. July 15, 1983.
Roberts Landing salt marsh harvest mouse trapping program.
21 Harvey and Stanley Associates. July 10, 1982. Hayward Marsh
expansion trapping results. East Bay Regional Park District.
22 Harvey and Stanley Associates. 1984. Hayward Marsh expansion,
salt marsh harvest mouse experimental translocation. East Bay
Regional Park District.
23 Gilroy, A. and H.S. Shellhammer. 1980. Trapping survey of salt
marsh harvest mice, Reithrodontomys raviventris raviventris, in the
marshes of South San Francisco Bay during the summer of 1980. San
Francisco Bay NWR, Newark, CA.
24 Shellhammer, H.S. 1985. Trapping studies of salt marsh harvest
mouse use of marginal habitats in the South San Francisco Bay.
San Jose State Univ. Foundation, for the Calif. Dept. Fish Game.
25 Wondolleck, J.T., W. Zolan, and G.L. Stevens. 1976. A population
study of harvest mice in the Palo Alto salt marsh. Wasmann J.
Biol. 34:52-64.
26 Michaels, J.L. June 1978. Personal communication. Then at Calif.
Dept. Fish Game, Yountville, CA.
27 Harvey and Stanley Associates. 1982. Rodent trapping at
Canalways, San Rafael, for David Coldoff.
28 Western Ecological Service Company. 1984. Personal communication.
29 Zetterquist, D. 1978. The salt marsh harvest mouse
(Reithrodontomys raviventris raviventris) in marginal habitats.
Wasmann J. Biol. 35:68-76.
30 Larkin, J.A. 1985. Estimating population size of a rare species.
M.A. Thesis, San Jose St. Univ.
References - 3