FIRE EFFECTS AND USE
WILDLIFE SPECIES: Sigmodon hispidus | Hispid Cotton Rat 



DIRECT FIRE EFFECTS ON ANIMALS : 
Mortality from fire is directly caused by burns, heat stress,
asphyxiation, physiological stress, trampling by other animals, or
predation while fleeing fire.  Indirect causes include changes in
quality and quantity of food, nest site availability, predation,
parasitism, disease, increased competition, and social interactions
[24].  Eastman [70] suggested that the dark, grizzled coloration of
hispid cotton rats helps protect them from predation after fire (it is
also adaptive coloration for a grassland rodent) [22].

Komarek [30] reported that fire occasionally kills hispid cotton rats
though they largely avoid fire by going into burrows or moving away from
flames.  Over the course of 225 prescribed fall and spring fires in
grasslands, he never found a dead or injured juvenile hispid cotton rat
even though he examined hundreds of recently burned or burning hispid
cotton rat nests.  He reported that the squeaking of hispid cotton rats
could be heard as the rats moved ahead of a fire.  He often observed
hispid cotton rats leading or carrying their young away from a fire.
They have also been observed running across firelines and returning to
smoking burns without injury [30].  Odum and others [48] reported that
the immediate reaction of hispid cotton rats to fire is to move to
unburned areas with protective cover.  They return to burned areas as
soon as foliage cover develops.

In southern Florida hispid cotton rat mortality from fire may be related
to the rate of fire spread.  In a muhlenbergia (Muhlenbergia spp.)
prairie Taylor [60] found one carcass of a hispid cotton rat (along with
carcasses of other small mammals) after a fast-spreading, severe fire,
but none after a slow-spreading fire.


HABITAT RELATED FIRE EFFECTS : 
The response of hispid cotton rats to fire is usually negative in the
very short term, but populations usually recover rapidly with the
recovery of vegetative cover.  Hispid cotton rats have been rated as
fire-negative, since they are associated with plant debris and are
foliage eaters [24], but they are often reported as increasing after
fire.  Bock and Bock [71] reported a decrease in hispid cotton rat
population after combined wildfires and prescribed fire in big sacaton
(Sporobolus wrightii) grasslands reduced big sacaton cover but
stimulated growth of forbs and other grasses.  Hispid cotton rats could
be classified as fire-positive since the lush vegetation produced during
the first few growing seasons following fire often supports relatively
large populations; hispid cotton rat populations are often highest in the
first few growing seasons after fire [22].  In Kansas tallgrass prairie
hispid cotton rats were captured most often in burned lowlands in the
fall following a late winter prescribed fire.  There were also large
numbers of hispid cotton rat in transition areas that had been burned 1
to 3 years before rats were censused.  In lowland areas vegetation on
burned patches was taller and denser than on unburned patches.  On
upland sites there was no significant difference between the number of
captures on unburned and burned sites, but there were slightly more
captures on the unburned site [49].  Ash from prairie fires had no
effect on the palatability of seed in captive feeding trials [51].

In Oklahoma blackjack oak (Quercus marilandica)-post oak (Q. stellata)
savanna, relative densities of hispid cotton rats were greatest on study
plots that were treated with herbicide to reduce shrubs, then burned
annually to maintain grassy cover.  Plots that were untreated succeeded
to dense brush and young trees and had reduced numbers of hispid cotton
rats.  Peak production of hispid cotton rats occurred in the second year
after herbicide treatment, the year of peak herbaceous dicot
productivity.  Hispid cotton rat numbers declined with repeated annual
burning; dicot density also decreased.  This decrease may have been an
important factor in the hispid cotton rat decline since dicots provide
higher quality forage than grass.  However, overall vegetative
productivity declined on the plots over the same time period and may
have been a more important factor than the amount of dicots present
[44].

In the Southeast open pine woodlands with surface cover of broomsedge
and herbs usually have mid-size populations of hispid cotton rats.  The
open condition of these woods is maintained by frequent fire.  Hispid
cotton rat populations peak 3 to 4 years after fire but decline with
longer intervals between fires [29,30].  Komarek [29] concluded that
frequent (annual or biennial) fire keeps hispid cotton rats from
becoming too abundant but also provides better habitat than no fire.  In
southeastern loblolly pine-shortleaf pine stands hispid cotton rats are
the dominant herbivorous rodent the first and second years after fire.
The early brush stage (postfire years 3 and 4) also supports abundant
hispid cotton rats, but hispid cotton rats decline thereafter.  No
hispid cotton rats were reported for plots that had not experienced fire
for 19 years [34].  In Georgia longleaf-slash pine forests that were
burned annually in spring typically supported hispid cotton rat
populations [5].  In north-central Florida pine flatwoods, hispid cotton
rats were not present on burned areas in the first 2 months following
December prescribed fire that burned all surface litter and vegetation.
Hispid cotton rats returned to the burned areas in spring; hispid cotton
rat abundance was greatest in the fall following the prescribed fire.
The first hispid cotton rats to be captured on the burn were subadult
males, but they were followed shortly thereafter by other hispid cotton
rats.  Females on the burn area apparently produced two litters each
during the first postfire growing season [38].

In Georgia fallow fields that had been cultivated for millet were
censused for small mammals before and after prescribed fire.  In March
approximately one-half acre of one of the plots was litter-burned.  Six
pairs of hispid cotton rats were introduced into two 1-acre enclosures
in April; by September there were 70 hispid cotton rats in each
enclosure.  In the first few weeks after the hispid cotton rats were
introduced to the enclosures they concentrated their activity on the
unburned portion of the plot where cover was greatest, but as the season
progressed they moved onto the burned area.  Hispid cotton rats on the
burned area gained slightly more weight than those on the unburned
areas, which suggested that there was more and/or better forage on the
burned areas [48].


FIRE USE : 
Komarek [29] stated that northern bobwhite management areas could be
kept from becoming overrun with hispid cotton rats through the use of
frequent (annual to biennial) prescribed fire in fall or spring.  This
management technique maintains northern bobwhite habitat and reduces
hispid cotton rat habitat to some extent.  Longer fire-free intervals
are more detrimental to northern bobwhite populations than is predation
by hispid cotton rats [29,30].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Sigmodon hispidus | Hispid Cotton Rat