Reithrodontomys Megalotis Research Articles

Influence of Mammal Activity on Nesting Success of Passerines

For many avian species, predation is the leading cause of nest failure. However, relationships between predator abundance and nest predation often differ across spatial scales. We examined the relationship between environmental characteristics in meadows and mammalian predator activity, the relationship between predator activity at 2 spatial scales, and the probability of nest predation of willow flycatchers (Empidonax traillii), dusky flycatchers (Empidonax oberholseri), and yellow warblers (Dendroica petechia) in the central Sierra Nevada Mountains, California, USA. Environmental characteristics associated with the detection of nest predators varied depending on species. Douglas's squirrel (Tamiasciurus douglasii) and chipmunks (Tamias spp.) were associated with characteristics common along edges of meadows; short-tailed weasels (Mustela erminea) were associated with willows, whereas mice (Peromyscus maniculatus, Reithrodontomys megalotis, and Microtus spp.) and long-tailed weasels (Mustela frenata) were distributed throughout the meadows. The probability of predation of willow and dusky flycatcher nests increased with increasing short-tailed weasel activity, and the probability of predation of yellow warbler nests increased with increasing activity of chipmunks and short-tailed weasels. Variation in the occurrence of predator species in different areas of the meadows likely influences the probability of nest predation by each species and the nesting success of birds. Identifying factors that influence the distribution and abundance of common nest predators will likely be integral to the development of conservation efforts to increase the reproductive success of some bird species.

IMPACT ON RODENTS OF MOWING STRIPS IN OLD FIELDS OF EASTERN KANSAS

To minimize impact on small mammals while preventing invasion of woody vegetation, we mowed alternating 15-m strips on our area. We then compared numbers and movements of 5 species of rodents on mowed and unmowed strips. Numbers of hispid cotton rats (Sigmodon hispidus) and prairie voles (Microtus ochrogaster) were reduced temporarily in the mowed strips, whereas numbers of white-footed mice (Peromyscus leucopus), deer mice (P. maniculatus), and western harvest mice (Reithrodontomys megalotis) did not change significantly. Movements of cotton rats, prairie voles, and harvest mice across mowed strips were reduced, whereas movements within unmowed strips were relatively unaffected, decreasing only for white-footed and harvest mice in 1 of 2 temporal replicates. Changes in numbers and movements were of short duration, and hence mowing narrow strips when vegetation could recover rapidly had little sustained impact on this rodent community.

Comparative effectiveness of Longworth and Sherman live traps

Despite the widespread use of Sherman (H. B. Sherman Inc., Tallahassee, Flor.) and Longworth (Penlon Ltd., Oxford, U.K.) live traps in small-mammal-community assessment, few studies have directly compared the effectiveness of these 2 popular models. This study compared the relative efficacy of both trap types in capturing small mammals in southern Wisconsin grasslands. As trap size may cause capture bias, we compared Longworth traps with equal numbers of small and large, folding Sherman traps. We also deployed a small number of pitfalls. We carried out trapping at 12 sites over a 2-year period (1996–1997). We observed a significant year effect, so we analyzed differences in capture success, species diversity indices, and percent community similarity between trap types separately for each year. Two-way contingency table analyses indicated that all 3 trap types exhibited species-specific differences in capture rates. We assessed standardized deviates for each cell within this two-way design, and we considered departures greater than 2 standard deviations (SE±1.96) from the mean to show an either significantly positive (≥ + 1.96) or significantly negative (≤ −1.96) association. In the first year, Longworth traps captured greater numbers of long-tailed shrews (Sorex spp.) whereas small Sherman traps captured more western harvest mice (Reithrodontomys megalotis) and white-footed or prairie deer mice (Peromyscus spp.). In the second year, small Sherman captures were greater for long-tailed shrews and western harvest mice while large Sherman traps captured more meadow voles (Microtus pennsylvanicus) and jumping mice (Zapus hudsonius). Although estimates of community diversity were similar between trap types, percent community similarity estimates were lowest for Longworth-Sherman trap comparisons. Mortality rates were highest for Longworth traps and small Sherman traps and lowest for large Sherman traps. Pitfalls caught proportionally more long-tailed shrews than conventional live traps in the first but not the second year of study. In general, body mass of the animal had little effect on trap capture rates. However, in the first year of this study, small Sherman traps caught lighter (P =0.028) long-tailed shrews than the large Sherman traps. Similarly, Longworth traps caught significantly lighter white-footed/prairie deer mice than either small (P=0.022) or large (P= 0.035) Shermans. When used in combination, both Longworth and Sherman traps can diminish overall sampling error and yield less biased estimates of species composition than either trap type alone. The use of new as opposed to used Sherman traps in the second year of this study might account for the greater capture efficacy of these traps and contribute to differences in relative trap type success between years.

SPATIAL CLUSTERING OF MURID RODENTS INFECTED WITH HANTAVIRUSES: IMPLICATIONS FROM META‐ANALYSES

We applied a rigorous, quantitative methodology to the analysis of local‐scale spatial clustering of multiple murid mice (brush mice, Peromyscus boylii; deer mice, P. maniculatus; piñon mice, P. truei; western harvest mice, Reithrodontomys megalotis) infected or uninfected with hantaviruses. Rodents were sampled longitudinally from 1994 to 2001 on 23 trapping webs at 10 locations in the southwestern United States. This study provided an opportunity to apply meta‐analysis techniques to an important ecological question. There were sufficient captures by species on 199 occasions (three consecutive nights) to compare general use of space using multi‐response permutation procedures (MRPP). The MRPP results were then used in meta‐analyses by species to determine if overall effects of spatial clustering of hantavirus‐infected mice as well as categorical effects (elevation, season, site, and state) were present. Based on MRPP analyses, overall spatial clustering of hantavirus‐infected mice was most pronounced for brush mice, followed by the deer mouse. Meta‐analyses indicated significant overall effects of spatial clustering and varying categorical effects (elevation, season, site, state) of infected mice for each species compared. The overlapping space use by rodents might be an important factor affecting the local transmission of several hantaviruses.

EPIZOOTIOLOGY OF SIN NOMBRE AND EL MORO CANYON HANTAVIRUSES, SOUTHEASTERN COLORADO, 1995–2000

Sin Nombre virus (SNV) is an etiologic agent of hantavirus pulmonary syndrome. To better understand the natural history of this virus we studied population dynamics and temporal pattern of infection of its rodent hosts in southeastern Colorado (USA) from 1995 to 2000. We present evidence for the presence of two hantaviruses, SNV in deer mice (Peromyscus maniculatus) and El Moro Canyon virus in western harvest mice (Reithrodontomys megalotis), at our study sites. Sin Nombre virus appeared only sporadically in deer mouse populations; overall prevalence of antibody to SNV was 2.6%. El Moro Canyon virus was enzootic: seroconversions occurred throughout the year; antibody prevalence (11.9% overall) showed a delayed-density-dependent pattern, peaking as relative abundance of mice was declining. Males of both host species were more frequently infected than were females. An apparently lower mean survivorship (persistence at the trapping site) for SNV antibody-positive deer mice could indicate a detrimental effect of SNV on its host, but might also be explained by the fact that antibody-positive mice were older when first captured.

POPULATION DYNAMICS OF A DIVERSE RODENT ASSEMBLAGE IN MIXED GRASS-SHRUB HABITAT, SOUTHEASTERN COLORADO, 1995–2000

We followed seasonal and year-to-year population dynamics for a diverse rodent assemblage in a short-grass prairie ecosystem in southeastern Colorado (USA) for 6 yr. We captured 2,798 individual rodents (range, one to 812 individuals per species) belonging to 19 species. The two most common species, deer mice (Peromyscus maniculatus) and western harvest mice (Reithrodontomys megalotis), generally had population peaks in winter and nadirs in summer; several other murid species demonstrated autumn peaks and spring nadirs; heteromyids were infrequently captured in winter, and populations generally peaked in summer or autumn. Inter-annual trends indicated an interactive effect between temperature and precipitation. Conditions associated with low rodent populations or population declines were high precipitation during cold periods (autumn and winter) and low precipitation during warm periods (spring and summer). Severity of adverse effects varied by species. Heteromyids, for example, were apparently not negatively affected by the hot, dry spring and summer of 2000. Cross-correlations for the temporal series of relative population abundances between species pairs (which are affected by both seasonal and interannual population dynamics) revealed positive associations among most murids and among most heteromyids, but there were negative associations between murids and heteromyids. These results have important implications for those attempting to model population dynamics of rodent populations for purposes of predicting disease risk.

Detection and characterization of Borrelia bissettii in rodents from the central California coast.

This is the first report of Borrelia burgdorferi sensu lato in rodents from San Luis Obispo county, with most isolates obtained from a previously unreported host, Neotoma lepida Thomas. B. burgdorferi sensu lato was identified in seven rodent species, including the California vole, Microtus californicus Peale; dusky-footed woodrat, Neotoma fuscipes Baird; desert woodrat, Neotoma lepida Thomas; brush mouse, Peromyscus boylii Baird; California mouse, Peromyscus californicus Gambel; deer mouse, Peromyscus maniculatus Wagner; and western harvest mouse, Reithrodontomys megalotis Baird. Ear punch biopsies were cultured in BSK-H medium from 179 rodents trapped at six different study sites. Overall, prevalence of rodent infection was 44/179 (24.6%), with 34 of these isolates from N. lepida. Spirochete isolates were obtained from rodents at all study sites, indicating widespread prevalence of B. burgdorferi sensu lato across rodent species and habitats. Nucleotide sequences for 14 of these isolates have been submitted to GenBank. Isolates from three N. lepida and one P. boylii had identical flagellin gene sequences, and phylogenetic analysis placed these spirochetes in B. burgdorferi sensu lato group DN127, now known as B. bissettii Postic, Marti Ras, Lane, Hendson & Baranton. Additional sequencing of the intergenic spacer regions between the 5S and 23S ribosomal genes was performed on three of these isolates. Phylogenetic analysis separated these isolates into two clusters that grouped with Colorado or California isolates. The role of B. bissettii and related species other than B. burgdorferi sensu stricto Johnson, Schmid, Hyde, Steigerwalt & Brenner as human pathogens in the United States warrants further investigation.

LONG-TERM DYNAMICS OF A GRASSLAND RODENT COMMUNITY

We examined long-term (1978–1999) population fluctuations and their influence on community structure in 6 species of rodents that are syntopic in old-field habitat in northeastern Kansas. Populations of all species fluctuated severalfold in abundance, with Sigmodon hispidus, Peromyscus maniculatus, and Reithrodontomys megalotis exhibiting annual cycles. Multiannual periodicities were evident for Microtus ochrogaster, P. maniculatus (3.5–4 years), and P. leucopus (7 years). Only Synaptomys cooperi lacked a discernable pattern in its abundance. Monthly abundances of 6 of 15 species-pairs positively covaried, suggesting similar responses to long-term environmental variation. In addition, several species-pairs showed time-lagged cross-correlations that indicate regular annual cycles, which were out of phase. Because of this variation in population dynamics within and among community members, the structure of this community varied considerably over time, indicating a nonequilibrial community. However, when looking at the community as a whole, 2 reoccurring long-term patterns in community structure emerge: an annual and a 3.5-year cycle. Annual cycles in community structure occurred because 3 of the 6 species showed annual cycles, whereas the 3.5-year cycle in community structure was probably due to the overwhelming influence of fluctuations in abundance of the numerically dominant prairie vole.

Long-Term Dynamics of a Grassland Rodent Community

We examined long-term (1978–1999) population fluctuations and their influence on community structure in 6 species of rodents that are syntopic in old-field habitat in northeastern Kansas. Populations of all species fluctuated severalfold in abundance, with Sigmodon hispidus, Peromyscus maniculatus, and Reithrodontomys megalotis exhibiting annual cycles. Multiannual periodicities were evident for Microtus ochrogaster, P. maniculatus, (3.5–4 years), and P. leucopus (7 years). Only Synaptomys cooperi lacked a discernable pattern in its abundance. Monthly abundances of 6 of 15 species-pairs positively covaried, suggesting similar responses to long-term environmental variation. In addition, several species-pairs showed time-lagged cross-correlations that indicate regular annual cycles, which were out of phase. Because of this variation in population dynamics within and among community members, the structure of this community varied considerably over time, indicating a nonequilibrial community. However, when looking at the community as a whole, 2 reoccurring long-term patterns in community structure emerge: an annual and a 3.5-year cycle. Annual cycles in community structure occurred because 3 of the 6 species showed annual cycles, whereas the 3.5-year cycle in community structure was probably due to the overwhelming influence of fluctuations in abundance of the numerically dominant prairie vole.

Influence of a granivorous diversionary food on population dynamics of montane voles ( Microtus montanus), deer mice ( Peromyscus maniculatus), and western harvest mice ( Reithrodontomys megalotis)

Feeding damage to forest and agricultural crops by voles of the genera Microtus and Clethrionomys occurs periodically in temperate and boreal ecosystems. Application of diversionary food is an alternative management practice that does not rely on a reduction in the target population. This study tested two hypotheses that a granivorous diversionary food, sunflower seeds, would (1) reduce feeding damage to tree seedlings by montane voles ( Microtus montanus) without enhancing abundance or other population attributes and (2) enhance population dynamics of non-target deer mice ( Peromyscus maniculatus) and western harvest mice ( Reithrodontomys megalotis) in old field habitats at Summerland, British Columbia, Canada in 1993–1995. Small mammal populations were intensively live-trapped on replicate control and food sites pre- and post-treatment in two (A and B) experiments (food application rates of 68.1 and 113.5 kg/ha). Mean abundance and recruitment of voles/ha were similar between control and treatment sites. Mean abundance and recruitment of deer mice was higher on treatment than control sites in Experiment B but not in A. Mean abundance and recruitment of western harvest mice was similar between control and treatment sites. Overall survival (28-day), early juvenile survival, and body mass showed no patterns for any of the species when comparing control and treatment sites. This granivorous diversionary food did not reduce feeding damage by voles to lodgepole pine ( Pinus contorta) seedlings. The supply of sunflower seed was likely insufficient to divert voles from feeding on trees through the overwinter (5–6 months) period. The predicted increase in numbers of deer mice and western harvest mice appeared only as brief pulses of animals, and hence may not have increased the intensity of competition with voles.

NOTEWORTHY RECORD OF WESTERN HARVEST MOUSE (MURIDAE: REITHRODONTOMYS MEGALOTIS) ON THE BAJA CALIFORNIA PENINSULA

In 1998, we made an inventory of mammals in the Valle de los Cirios Reserve of the central portion of the state of Baja California, Mexico. New records of Reithrodontomys megalotis were obtained and were collected in 3 years at the same locality. This species is restricted to small marshes within an arid region. The range expanded 230 km to the south.

ECTOPARASITES OF SMALL MAMMALS FROM THE NEWPORT CHEMICAL DEPOT, VERMILLION COUNTY, INDIANA

Ectoparasites of various species of bats, carnivores, insectivores, and rodents were examined from the Newport Chemical Depot in Vermillion County, Indiana. A total of 16 species of hosts was examined for ectoparasites, including Blarina brevicauda, Eptesicus fuscus, Microtus ochrogaster, Microtus pennsylvanicus, Mus musculus, Mustela frenata, Mustela vison, Myotis lucifugus, Myotis septentrionalis, Peromyscus leucopus, Peromyscus maniculatus, Reithrodontomys megalotis, Sorex cinereus, Synaptomys cooperi, Tamias striatus, and Zapus hudsonius. The 49 species of ectoparasites recovered included four fleas, four sucking lice, one true bug, two ticks, and 38 mites. Thirty-two new ectoparasitic host records are reported for Indiana, of which 16 are new records for respective hosts throughout their entire range.

Rodent Communities in a Grazed and Ungrazed Arizona Grassland, and a Model of Habitat Relationships Among Rodents in Southwestern Grass/Shrublands

We live-trapped rodents in 2000–2001 at eight sites on a 3160 ha grassland and mesquite-oak savanna in southeastern Arizona that had been ungrazed since 1968, and on eight paired sites on adjacent cattle ranches. There were 917 captures of 14 species during 5760 trap-nights. Four species of Muridae (Sigmodon fulviventer, Baiomys taylori, Reithrodontomys megalotis and R. fulvescens) were significantly more common on ungrazed plots, while no species was more abundant on grazed plots. However, Heteromyidae as a group (especially Chaetodipus hispidus and Perognathus flavus) comprised a significantly higher proportion of total captures on grazed plots, and heteromyids as a percentage of total captures was positively correlated across all plots with amount of bare ground. One of the eight cross-fence sites also had been trapped in 1981–1983. In the 17 y between trapping events at this site: (1) the grass canopy on both grazed and ungrazed plots had become dominated by taller species, (2) a kangaroo rat (Dipodomys merriami) that had been the second most common species in grazed areas disappeared from both plots, (3) pocket mice increased on the grazed plot and declined on the ungrazed plot and (4) Muridae (excluding Peromyscus) as a percent of all captures increased by greater than 1.5-fold on both plots. Based on these results, and those from other field studies, we propose a model for the composition of rodent communities in grass/shrublands of the Southwest and Intermountain West, based on ground cover. Kangaroo rats (Dipodomys spp.) are abundant in areas with the most bare soil, Muridae (specifically, Sigmodon, Baiomys and Reithrodontomys) dominate areas with the most and tallest ground cover, and pocket mice (Chaetodipus and Perognathus) are common in areas of intermediate cover. In relatively mesic grasslands, livestock grazing and fire drive the rodent community toward one dominated by heteromyids instead of murids. In more arid landscapes, grazing and fire favor kangaroo rats over pocket mice.

Impacts of small mammals and birds on low-tillage, dryland crops

During 2000–2001, small mammals, birds, and potential corn/soybean damage were studied at a low-tillage, non-irrigated agricultural research site in the Colorado Piedmont. A small mammal survey involved four trapping sessions and 18, 12-live-trap grids each. Within years, two grids each were placed at random, fixed locations in experimental corn, fallow, millet, pea, soybean, sunflower, and wheat plots at the site; two off-plot grids each were set at random, fixed locations <100 m from the north and south edge of these plots. In 2001, periodic bird observations were conducted, and damage to corn and soybean plants was assessed. Capture rates were low during all trap sessions (range 0.1%–3.3%, X ̄ =2.2% ). Sixty-three small mammals were captured and 39 were recaptured. Captures included deer mouse ( Peromyscus maniculatus), northern grasshopper mouse ( Onychomys leucogaster), thirteen-lined ground squirrel ( Spermophilus tridecemlineatus), and western harvest mouse ( Reithrodontomys megalotis). Deer mice accounted for 56 of the initial captures (88.9%). In-crop captures ( n=15) and recaptures ( n=16) were most frequent in wheat plots. Bird counts were low and included horned lark ( Eremophila alpestris), killdeer plover ( Charadrius vociferus), lark bunting ( Calamospiza melanocorys), mountain plover ( Charadrius montanus), mourning dove ( Zenaida macroura), and western meadowlark ( Sturnella neglecta). No direct seed removal, sprout removal, or plant clipping by small mammals or birds was observed, but some clipping of soybean plants was attributed to deer ( Odocoileus virginianus and O. hemionus) and jack rabbits ( Lepus townsendii or L. californicus). Plant debris accumulation is viewed as a key factor determining small mammal abundance and potential damage in low-till agriculture.

Small-Mammal Data on Early and Middle Holocene Climates and Biotic Communities in the Bonneville Basin, USA

Archaeological investigations in Camels Back Cave, western Utah, recovered a series of small-mammal bone assemblages from stratified deposits dating between ca. 12,000 and 500 14C yr B.P. The cave's early Holocene fauna includes a number of species adapted to montane or mesic habitats containing grasses and/or sagebrush (e.g., Lepus townsendii, Marmota flaviventris, Reithrodontomys megalotis, and Brachylagus idahoensis) which suggest that the region was relatively cool and moist until after 8800 14C yr B.P. Between ca. 8600 and 8100 14C yr B.P. these mammals became locally extinct, taxonomic diversity declined, and there was an increase in species well-adapted to xeric, low-elevation habitats, including ground squirrels, Lepus californicus and Neotoma lepida. The early small-mammal record from Camels Back Cave is similar to the 11,300–6000 14C yr B.P. mammalian sequence from Homestead Cave, northwestern Utah, and provides corroborative data on Bonneville Basin paleoenvironments and mammalian responses to middle Holocene desertification.

Genetic identification and characterization of limestone canyon virus, a unique Peromyscus-borne hantavirus.

Hantaviruses, family Bunyaviridae, are rodent-borne RNA viruses that can cause hantavirus pulmonary syndrome (HPS) in various regions of the Americas. A coevolutionary relationship exists between hantaviruses and their specific rodent reservoir hosts; the phylogeny of the viruses generally matches that of the rodents. There are several Peromyscus-borne hantaviruses, including Sin Nombre virus, the most common cause of HPS in North America. This report describes the genetic detection and characterization of a newly discovered Peromyscus boylii-borne virus, Limestone Canyon (LSC) virus, the most divergent member of the Peromyscus-borne hantaviruses to date. Analysis of a 1209-nucleotide region of the S segment of LSC virus showed it to be more closely related to hantaviruses found in harvest mice (Reithrodontomys megalotis and R. mexicanus) than to other Peromyscus-associated hantaviruses (Sin Nombre, New York, and Monongahela). Phylogenetic analysis of virtually the entire M genome segment (3489 nucleotides) of LSC virus revealed a similar picture in which LSC virus was found to be very distinct from other Peromyscus-associated viruses, but its exact relationship to the other Peromyscus-borne and the Reithrodontomys-borne viruses was not resolved. These results indicate that hantavirus host species-jumping events can occur by which a hantavirus may switch to, and become established in, a rodent host belonging to a different genus. P. boylii are present throughout the southwestern United States and central Mexico. More extensive screening of HPS patients by using RT-PCR assays will be necessary to determine if LSC virus can cause human disease.

Do unusual site-specific population dynamics of rodent reservoirs provide clues to the natural history of hantaviruses?

Between January 1995 and November 1997, longitudinal mark-recapture studies of rodent hosts of hantaviruses in a disturbed microhabitat within a shortgrass prairie ecosystem in southeastern Colorado (USA) were conducted. The site was distinguished by edaphic and floristic characteristics unique to this area and associated with historical land use patterns, as well as the year-around availability of water from a functioning windmill. Populations of two common rodent species that are hosts for hantaviruses, Peromyscus maniculatus and Reithrodontomys megalotis, had unusually rapid turnover, a younger age structure, and a much lower prevalence of antibody to Sin Nombre virus than did populations at nearby sites in more typical shortgrass prairie and canyon habitats. Based on these findings, we suggest that a stable resident population of the reservoir is critical to the maintenance of hantaviruses at a given site, and we hypothesize that long-lived, persistently infected rodents are the principal transseasonal reservoir of hantaviruses.

Pneumocystosis in wild small mammals from California.

Cyst forms of the opportunistic fungal parasite Pneumocystis carinii were found in the lungs of 34% of the desert shrew, Notiosorex crawfordi (n = 59), 13% of the ornate shrew, Sorex ornatus (n = 55), 6% of the dusky-footed wood rat, Neotoma fuscipes (n = 16), 2.5% of the California meadow vole, Microtus californicus (n = 40), and 50% of the California pocket mouse, Chaetodipus californicus (n = 2) caught from southern California between February 1998 and February 2000. Cysts were not found in any of the harvest mouse, Reithrodontomys megalotis (n = 21), California mouse, Peromyscus californicus (n = 20), brush mouse, Peromyscus boylii (n = 7) or deer mouse, Peromyscus maniculatus (n = 4) examined. All infections were mild; extrapulmonary infections were not observed. Other lung parasites detected were Hepatozoon sp./spp. from M. californicus and Notiosorex crawfordi, Chrysosporium sp. (Emmonsia) from M. californicus, and a nematode from S. ornatus.

Arenavirus antibody in rodents indigenous to coastal southern California.

The purpose of this study was to extend our knowledge on the geographic and natural rodent host ranges of New World arenaviruses in California. Sera from 1,094 sigmodontine and 112 murine rodents were tested for antibody against Whitewater Arroyo and Amapari viruses. Antibody was found in 55 (4.6%) of the 1,206 rodents: 4 from northwestern San Diego County, 3 from Los Angeles County, and 48 from Orange County. The antibody-positive rodents included 8 (7.8%) of 103 Neotoma fuscipes, 1 (0.6%) of 180 Neotoma lepida, 1 (3.1%) of 32 Peromyscus boylii, 8 (11.0%) of 73 Peromyscus californicus, 1 (1.2%) of 85 Peromyscus eremicus, 30 (8.5%) of 353 Peromyscus maniculatus, and 6 (2.2%) of 268 Reithrodontomys megalotis. This study provides the first evidence that New World arenaviruses occur in Los Angeles and Orange counties and northwestern San Diego County, and the first evidence that Peromyscus and Reithrodontomys species are naturally infected with New World arenaviruses.

Small Mammals in Central Kansas Windbreaks in Winter

Field windbreaks consist of trees, shrubs, or a combination of both planted adjacent to fields or farmsteads to reduce the force of wind. Kansas has about 4,900 ha of farmstead windbreaks and 118,000 ha of field windbreaks (Soil Conservation Service, 1994). Johnson and Beck (1988) reviewed the literature and identified references to 28 species of mammals using windbreaks with seven species classified as high dependence/high use. The purpose of this study was to determine which small mammal species use field windbreaks in central Kansas during winter. Twenty field windbreaks of variable size (0.28 ha-11.66 ha) were studied in Stafford and Pawnee counties, Kansas. The number of rows in the windbreaks ranged from 1 to 17, with a mean of 6.7 rows. The most frequently occurring tree species in the windbreaks were eastern cottonwood (Populus deltoides) occurring in 100% of the windbreaks, eastern redcedar (Juniperus virginiana) (85%), Siberian elm (Ulmus pumila) (55%), honey locust, (Gleditsia triacanthos) (50%) and Osage orange (Maclura pomifera) (50%). Small mammal trapping was conducted during mid-February. Twenty-five trapping stations were set at 5-meter intervals along a transect that bisected each windbreak. Each station had one Sherman live trap (3 in x 3.5 in x 12 in) and one museum special snap trap (2.75 in x 5.5 in), baited with a mixture of peanut butter and oats. Trapping was conducted for three consecutive nights in each windbreak, resulting in 150 trap-nights per windbreak and a total of 3,000 trap-nights during the course of the sampling period. One hundred and forty-nine captures of six small mammal species were made in the 20 windbreaks. The species captured were white-footed mouse (Peromyscus leucopus), deer mouse (P. maniculatus), cotton rat (Sigmodon hispidus), western harvest mouse (Reithrodontomys megalotis), Elliot's short-tailed shrew (Blarina hylophaga), and house mouse (Mus musculus). Eighteen of the 20 windbreaks (90%) contained at least one species of small mammal, and one windbreak contained five of the six species, lacking only the Elliot's short-tailed shrew. The average number of small mammal species per windbreak was 1.75. The white-footed mouse was the species most often captured (51.7% of total captures), followed by deer mouse (40.2%), western