Southern Illinois University-Carbondale,
with funding support from the Depart-ment
of Natural Resources, will be
investigating this species in greater
detail in the coming three years. The
research goal is to reassess the rice rat’s
status and, if warranted, make a recom-mendation
to the Illinois Endangered
Species Protection Board to review the
species’ status and consider if it should
be removed from Illinois’ list of endan-gered
and threatened species.
From March to October each year,
rice rats will be captured using small
aluminum traps baited with birdseed.
Traps will be laid out at fluctuating nat-ural
wetlands within the Mississippi
River floodplain, as well as in perma-nent
wetlands associated with
reclaimed mines. When an animal is
captured, it will be tagged with a small
microchip (similar to those inserted
into pets for identification) so that it
can be identified upon recapture. Some
animals will even be fitted with radio
collars—small and light enough to not
impair their movements, enabling them
to go about their daily routines unhin-dered—
which will allow tracking them
with a receiver up to 100 meters away.
Using microchip and radio transmit-ter
data, researchers will be able to
monitor distances moved by individuals,
habitats used and general patterns of
dispersal between small populations of
rice rats in different wetlands. In addi-tion,
the trapping information will allow
an estimate of the number of animals in
each area. If the data indicates that large
populations of rice rats are dispersing
between wetlands and increasing in
numbers over the three years, a propos-al
may be submitted to remove the
species from the threatened list.
In addition to monitoring movement
patterns, researchers also will investi-gate
the diet of rice rats.
It is generally believed that rice rats
have a diverse diet, including seeds,
insects, snails and even fish and carcass-es
of mice and birds. It is unknown how
their diet changes through seasons, or if
their diet differs between river flood-plains
and reclaimed mine wetlands.
Researchers will use the new tech-nique
of stable isotope analysis to
assess variation in the rice rat’s diet.
Plants and animals have different “signa-tures”
for carbon and nitrogen, and
analysis of rice rat fur will give an indi-cation
of the proportion of plant and
animal foods in their diet over the
recent past (3-4 months).
Rice rats serve an important function
in ecosystems, being preyed on by vari-ous
raptors and carnivores as well as
aiding in controlling some invertebrate
wetlands species. Through this
research project, information will be
gathered on a rice rat’s place in the
food web, helping build a greater
understanding of Illinois’ complex wet-land
Delisting a species
Illinois law requires that the Illinois
Endangered Species Protection
Board review, and revise as necessary,
the list of threatened and endangered
species at least once every five years.
Changes to the list must be based on
scientific evidence, such as changes in
population size or range in the state,
whether it occurs at protected sites,
any known threats to its existence and
features of its life history which might
have a bearing on survival. Scientists
with expertise in flora and fauna serve
on technical advisory committees and
advise IESPB on possible revisions.
The board may remove from the Illi-nois
list non-federally listed species no
longer endangered or threatened in Illi-nois.
A public hearing is held to consid-er
the board’s action of listing, delisting
or changing the list status of a species.
For further information on the
endangered and threatened species
process, visit www.dnr.state.il.us/
How extensive are populations
of the state-threatened marsh
rice rat? SIU scientists
are looking for
Marsh Rice Rat
Story By Jorista van der Merwe
They can be big or small, found
in dry or wet climates, near
the coast or far inland. Regard-less
of size, shape or location,
wetlands are invaluable to
wildlife and aquatic animals.
Often, the primary activity associated
with wetlands is hunting. However, wet-lands
provide much more than a spot for
a duck blind. Wetlands are diverse
ecosystems, rich in water-loving plant
species, frogs, birds, highly-adapted and
fascinating invertebrates such as insects
and snails, and, of course, furry mam-mals
adapted for life in or near water.
The early 1900s saw the destruction
of nearly 10 percent of wetlands in the
United States, mainly due to extensive
mining activities, large-scale agricultur-al
practices as well as the booming and
ever-expanding human populations
seeking more land for residential and
urban development. The decrease in
valuable wetland surface area led to a
decline in many animal species that
live in and around wetlands, including
60-75 percent of the species of birds
and amphibians in the United States
and up to seven wetland-associated
mammal species now considered
threatened or endangered. Under
recent programs, such as the 1985
federal Farm Bill, Wet-lands
Program and Intera-gency
Act of 1989, the
U.S. has experienced an
increase in acreage classi-fied
as freshwater wetland.
One important, but relatively
unknown, furry wetland inhabitant is
the marsh rice rat (Oryzomys palus-tris).
Small enough to fit in your hand,
at first glance the marsh rice rat resem-bles
a large house mouse. A closer look
reveals rougher fur, a hairless tail and
big, tough feet to facilitate swimming.
These small mammals inhabit wet-land
areas, including marshes and
swamps, either man-made or natural.
They occur in the southeastern United
States and reach the northern limit of
their distribution in Illinois, where they
are a state-threatened species, a listing
that means the marsh rice rat is vulnera-ble
to possible endangerment in Illinois.
A group of researchers with the
Cooperative Wildlife Research Lab at
The marsh rice rat inhabits natural
and reclaimed-mined wetlands in
extreme southern Illinois.
Researchers from Southern
Illinois University will aid in
determining if the rice rat should
be removed from Illinois’ list
of threatened mammals.
Jorista van der Merwe is a doctoral
student at Southern Illinois University-
Carbondale and can be reached at jvan
July 2011 OutdoorIllinois / 11
(>10 years old)
10 / OutdoorIllinois July 2011
(Photo courtesy Scott Cooney.)
(Photo courtesy Kenneth Delahunt.)
(Photo courtesy Jorista van der Merwe.)
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