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2009 SOUTHEASTERN NATURALIST 8(3):381–386
Temporal Variation of a Small-mammal Community at a
Wetland Restoration Site in Arkansas
Tiffany A. Whitsitt1 and Philip A. Tappe1,*
Abstract - Small mammals serve many ecological roles and contribute to wildlife
diversity in wetlands. We investigated a small-mammal community on a southeastern
Arkansas wetland-restoration site by trapping monthly from February through October
2007. During 8675 trap nights, 886 captures of six species and 615 individuals
were recorded. The numbers and proportions of individuals captured varied monthly
by species. Documentation of monthly fl uctuations in the composition and numbers
of this small-mammal community provides a basis by which to evaluate future restoration
Small mammals serve ecological roles in terrestrial ecosystems, including
as a primary prey base for several mammalian, avian, and reptilian
predators (Carey and Johnson 1995, Preston 1990, Soutiere 1979) and as
facilitators for the dispersal of fungal spores that form root-inhabiting ectomycorrhizae
required by many plants for nutrient procurement (Carey and
Johnson 1995, Maser et al. 1978). Small mammals can also impact the regeneration
of plants through consumption and dispersal of seeds (Chambers
and MacMahon 1994).
Hydrological processes control the life processes of animals that live
in wetland habitats. Historically, the Lower Mississippi Alluvial Valley in
Arkansas was composed of wetlands containing bottomland hardwoods. Approximately
85,000 ha of forested wetlands were converted for agriculture in
Arkansas from the mid-1970s to the mid-1980s (Hefner et al. 1994). Many
farmers are now trying to convert these areas back to their original condition
because of declines in their agricultural value (Smith 2001). Restoration
practices in the Arkansas Delta include the creation of wildlife habitat
mounds and basins, water-control structures, asymmetrical meandering
mounds, meander scrolls, and vernal pools (Smith 2001). These techniques
aim to diversify the habitats available for the regional fl ora and fauna.
The Bob White Memorial Wetlands Research and Teaching Station
(BWMW) allowed us to study small-mammal communities within a wetland
system. Baseline inventory data and a greater understanding of the current
small-mammal community at this site are needed to understand the impact
of current and future management practices. Our objectives were to inventory
small mammals and assess temporal variation in numbers of individuals
captured and species richness.
1110 University Court, Monticello, AR 71656. *Corresponding author - tappe@
382 Southeastern Naturalist Vol. 8, No. 3
Owned by the University of Arkansas at Monticello (UAM), the BWMW
is a 148-ha tract of land located in southwestern Chicot County, the southeastern-
most county in Arkansas. This property was used for agricultural purposes
(wheat, milo, rice) until enrolled as a permanent Wetland Reserve Program
(WRP) easement in 2001. Restoration practices were implemented in 2002
and 2003 through the Natural Resources Conservation Service (NRCS).
Primary vegetation at the site was Typha spp. L. (cattails), Baccharis halimifolia
L. (Eastern Baccharis), Lythrum alatum Pursh (Winged Loosestrife),
and hardwood seedlings including: Quercus nuttallii Palmer (Nuttall Oak),
Fraxinus pennsylvanica Marsh (Green Ash), Carya illinoinensis (Wangenh.)
K. Koch (Pecan), Quercus nigra L. (Water Oak), Quercus shumardii Buckl.
(Shumard Oak), Taxodium distichum (L.) L.C. Rich (Bald Cypress), and
Quercus lyrata Walt. (Overcup Oak).
Located within the Lower Mississippi Alluvial Valley, this property is
inundated with water during the winter, with small pools persisting most
of the year. Restoration of the site included planting hardwood seedlings
throughout the property in 2002 and 2003, with the intention of restoring this
site to bottomland hardwoods.
Microtopography was introduced to the site by creating basin and mound
complexes throughout the central portion of the tract. Basins were designed
with irregular profiles to increase the habitat available for waterfowl. Excavated
fill from these basins were contoured into mounds adjacent to the
basins. Mounds at this site typically ranged from 300–800 m2, with the difference
in elevation from the basins to mounds ranging from 1–1.5 m.
We captured small mammals using a total of 196 collapsible aluminum
Sherman live traps (7.5 x 9 x 23 cm; H.B. Sherman Traps, Inc., Tallahassee,
FL) baited with dry rolled oats and spaced at 15 m within four, 0.8-ha, 7 x 7
grids. We placed grids to include basin and mound complexes; grids were
>100 m apart. We placed traps no further than 1 m from grid points and along
natural habitat features (e.g., runways, trees, burrows; Jones et al. 1996)
when available. At times, trap sites were located in standing water due to
inundation. If vegetation was present (e.g., cattails), we tied plants together
using twine and wedged the Sherman live trap among the plants as close to
the water as possible. This provided enough stability for small mammals to
safely enter the trap. In the rare case (i.e., 1–5 sites) that this could not be
accomplished, a trap was not set at that location.
Trapping sessions were five days in length and took place monthly from
February to October 2007. We baited traps using rolled oats because peanut
butter lures other organisms including Solenopsis invicta Buren (Red
Imported Fire Ant) (Dueser and Shugart 1978). We re-baited the traps as
needed. Two researchers checked the grids early every morning to prevent
2009 T.A. Whitsitt and P.A. Tappe 383
captured small mammals from being exposed to excessive environmental
stresses. We documented sprung traps that contained no specimen or nontarget
captures. We identified captured rodents to species level, with the
exception of Peromyscus spp. We recorded relevant data including trap
site, gender, weight, and recapture status. Individuals were released at the
capture site. Capture and release followed American Society of Mammalogist
guidelines (Animal Care and Use Committee 1998) and were approved
by the UAM Institutional Animal Care and Use Committee (#200601). We
combined data from all of the grids and calculated numbers of individuals
captured by species and richness (number of species) for each month.
Results and Discussion
During 8675 trap nights, we recorded 886 captures of 615 individuals.
We captured six species, including Sigmodon hispidus Say and Ord (Hispid
Cotton Rat; 69.1% of individuals captured), Oryzomys palustris Harlan
(Marsh Rice Rat; 18.9%), Mus musculus L. (House Mouse; 4.2%), Peromyscus
spp. (deer mice; 2.9%), Reithrodontomys fulvescens J.A. Allen (Fulvous
Harvest Mouse; 4.1%), and Cryptotis parva Say (Least Shrew; 0.8%). Species
richness varied by month, with March and April having the greatest
richness and August having the least (Fig. 1). The numbers of individuals
Figure 1. Numbers of small-mammal species recorded by month on a wetland restoration
site in southeastern Arkansas, 2007.
384 Southeastern Naturalist Vol. 8, No. 3
captured differed among months, with July having the greatest number of
captures and March having the least (Fig. 2).
The numbers and proportions of individuals captured varied monthly by
species (Fig. 2). Marsh Rice Rat represented the greatest proportion of total
captures in February–April; however, during May–October, Hispid Cotton
Rat comprised the greatest proportion of captures. Most House Mice were
Figure 2. Numbers of small-mammal captures (at top of columns) and percent of
captures by species on a wetland restoration site in southeastern Arkansas, February–
2009 T.A. Whitsitt and P.A. Tappe 385
captured during February–April, whereas the greatest numbers of Fulvous
Harvest Mouse were captured in April–May, and Peromyscus spp. in February.
Least Shrew were captured in June only.
Community characteristics of small mammals varied temporally at this
site. Peaks in relative abundance of small-mammal species did not occur simultaneously;
Marsh Rice Rat captures were greatest in February and Hispid
Cotton Rat captures peaked in July. Increased captures of Marsh Rice Rat
in February were likely due to the amount of water on the site during this
period, and because this species is semi aquatic (Esher et al. 1978) and can
utilize areas with standing water more efficiently than other small mammals
(Abuzeineh et al. 2007, Wolfe 1982). The subsequent decline in captures of
Marsh Rice Rat may be attributable to the decline in water and the proliferation
of Hispid Cotton Rat.
Hispid Cotton Rat captures were comparatively low in February–April,
likely due to mortalities during winter (Fleharty et al. 1972). Species richness
was greatest in March and April. This peak in richness coincided
with lower relative abundances of Hispid Cotton Rat, which is known to
be aggressive toward other small-mammal species living in the same area
(Schwartz and Schwartz 2001). Hispid Cotton Rat may have excluded Marsh
Rice Rat, House Mice, Peromyscus spp., and potentially other small rodents
from this area during summer months.
Greater captures per unit effort and species richness were recorded in our
study compared to a similar study in Mississippi (Chamberlain and Leopold
2003). The Mississippi study site had fl at topography and contained little
vegetation during the fl ooding period. Greater relative abundance and richness
of small mammals could be due to the microtopography created by the
basin and mound complexes at our study site. Similar to our study, Martin et
al. (1991) captured Marsh Rice Rat, Fulvous Harvest Mouse, House Mice,
and Least Shrew among different marsh types and adjacent levees during the
winter and spring months of a single year in southwestern Louisiana.
Monthly variations in the small-mammal community at our study site were
likely due to changes in amount of water coupled with species interactions.
Species richness was possibly infl uenced by microtopography created by the
basin and mound complexes. Our inventory and documentation of smallmammal
community changes at this site provide a baseline with which to
examine future management practices. Management practices that infl uence
water levels and duration will likely infl uence small-mammal community
characteristics. Additional investigations of small-mammal communities are
warranted at other wetland sites and additional spatial scales to supplement
and expand our investigation.
We are grateful for the funding and support provided by the Bob White Memorial
Foundation, University of Arkansas at Monticello, and Arkansas Forest Resources
Center (AFRC). Additional appreciation is extended to C. Watt, L. Criswell, C.
386 Southeastern Naturalist Vol. 8, No. 3
Barton, A. Schenk, and S. Breedlove for assisting with data collection. We would also
like to thank the numerous AFRC faculty for their assistance.
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