Rodent Habitat Research Articles

Ammonia Removal from Rodent Habitat Operations in Space Using Phosphoric Acid Treated Activated Carbon

To accommodate long duration biology research with rodent habitats on the International Space Station while providing a healthy living and working environment for crewmembers, NASA Ames Research Center developed a new exhaust filter for odor control for the Animal Enclosure Module (AEM), which houses mice and rats. The new exhaust filter uses activated carbon pellets as adsorbents, with phosphoric acid (H3PO4) impregnated on the surface. The deodorization performance of the new exhaust filters for AEM units housed with mice was evaluated. The ammonia breakthrough time of the exhaust filters was also investigated. The results indicated that H3PO4 treated activated carbon exhibited a high ammonia adsorption capacity of more than 90%. Furthermore, the new exhaust filter can effectively control the odor from the AEM units for a 45-day (minimum) flight mission with a given animal biomass.

A Geographic Information Systems (GIS)-based analysis of modern South African rodent distributions, habitat use, and environmental tolerances

Goals of this study were to: (1) develop distributional maps of modern rodent genera throughout the countries of South Africa, Lesotho, and Swaziland by georeferencing museum specimens; (2) assess habitat preferences for genera by cross-referencing locality position with South African vegetation; and (3) identify mean annual precipitation and temperature range where the genera are located. Conterminous South Africa including the countries of Lesotho and Swaziland Digital databases of rodent museum specimens housed in the Ditsong National Museum of Natural History, South Africa (DM), and the Division of Mammals, National Museum of Natural History, Smithsonian Institution, United States (NMNH), were acquired and then sorted into a subset of specimens with associated coordinate data. The coordinate data were then used to develop distributional maps for the rodent genera present within the study area. Percent habitat occupation and descriptive statistics for six climatic variables were then determined for each genus by cross-referencing locality positions with vegetation and climatic maps. This report presents a series of maps illustrating the distribution of 35 rodent genera based on 19,471 geo-referenced specimens obtained from two major collections. Inferred habitat use by taxon is provided for both locality and specimen percent occurrence at three hierarchical habitat levels: biome, bioregion, and vegetation unit. Descriptive statistics for six climatic variables are also provided for each genus based on locality and specimen percent incidence. As rodent faunas are commonly used in paleoenvironmental reconstructions, an accurate assessment of rodent environmental tolerance ranges is necessary before confidence can be placed in an actualistic model. While the data presented here represent only a subset of the modern geographic distributions for many of the taxa examined, a wide range of environmental regimes are observed, suggesting that more research is necessary in order to accurately reconstruct an environmental signature when these taxa are found in the fossil record.

Rodent diversity and habitat use in a protected area of Buenos Aires province, Argentina

Habitat use of rodents is associated to environmental variables, species requirements and biological interactions. The aim of this study was to analyse the macro and microhabitat use and spatial variation in the abundance of small sylvan rodents that inhabit Otamendi Natural Reserve, Argentina. We studied rodent communities in six habitats: riparian forest, Celtis tala forest, lowland grassland, salt marsh and two highland grasslands. We captured a total of 153 individual of Scapteromys aquaticus Thomas 1920, Akodon azarae Fischer 1829, Oxymycterus rufus Fischer 1814, Oligoryzomys flavescens Waterhouse 1837, Deltamys kempi Thomas 1917 and O. nigripes Olfers 1818 with a trapping effort of 3636 trap-nights. The species richness is maintained by the presence of different habitats that satisfy specific requirements from specialist species to more generalist species using differentially the reserve and forming communities of different specific composition in each habitat. A differential macrohabitat use by all species and a certain level of selectivity at microhabitat scale in individuals of two species were observed. This study shown that the diversity of environments of a Natural Reserves allows the maintenance of many sylvan species of small rodents; confirming the high ecological and conservational value of the reserves inside an urban region.

Temporal dynamics and impact of climate factors on the incidence of zoonotic cutaneous leishmaniasis in central Tunisia.

BackgroundOld world Zoonotic Cutaneous Leishmaniasis (ZCL) is a vector-borne human disease caused by Leishmania major, a unicellular eukaryotic parasite transmitted by pool blood-feeding sand flies mainly to wild rodents, such as Psammomys obesus. The human beings who share the rodent and sand fly habitats can be subverted as both sand fly blood resource. ZCL is endemic in the Middle East, Central Asia, Subsaharan and North Africa. Like other vector-borne diseases, the incidence of ZCL displayed by humans varies with environmental and climate factors. However, so far no study has addressed the temporal dynamics or the impact of climate factors on the ZCL risk.Principal FindingsSeasonality during the same epidemiologic year and interval between ZCL epidemics ranging from 4 to 7 years were demonstrated. Models showed that ZCL incidence is raising i) by 1.8% (95% confidence intervals CI:0.0–3.6%) when there is 1 mm increase in the rainfall lagged by 12 to 14 months ii) by 5.0% (95% CI: 0.8–9.4%) when there is a 1% increase in humidity from July to September in the same epidemiologic year.Conclusion/SignificanceHigher rainfall is expected to result in increased density of chenopods, a halophytic plant that constitutes the exclusive food of Psammomys obesus. Consequently, following a high density of Psammomys obesus, the pool of Leishmania major transmissible from the rodents to blood-feeding female sand flies could lead to a higher probability of transmission to humans over the next season. These findings provide the evidence that ZCL is highly influenced by climate factors that could affect both Psammomys obesus and the sand fly population densities.

Effects of Turf Rolling and Soil Aeration on Rodent Populations

Author(s): Witmer, Gary; Borrowman, David | Abstract: Rodent populations at airports can cause human safety issues by attracting raptors which increases the risk of raptor-aircraft strikes. Various methods can be used to reduce rodent numbers, including trapping, poisoning, and habitat manipulation. Burrow disruption by turf rolling and soil aeration is a potential habitat manipulation method that could potentially reduce the carrying capacity for rodents. We tested this method at Kansas City International Airport, Missouri. We monitored the rodent populations in a control (untreated) area and in a nearby treated area where the turf was rolled and the soil aerated. We used grids of live traps to determine rodent abundance in the two areas. Unfortunately, the turf rolling and aeration did not reduce the rodent population, as we recorded 14-15 rodent captures per 100 trap-nights on both areas. We caution, however, that this was a very preliminary assessment, and the method could be further investigated for its potential to reduce rodent populations.

Abundance, age structure and reproductive patterns of Rattus norvegicus and Mus musculus in two areas of the city of Buenos Aires

The aim of this research was to compare the abundance, growth, age structure and reproductive patterns of Rattus norvegicus and Mus musculus populations of a shanty town and a parkland in the city of Buenos Aires, Argentina. Live trapping of rodents was conducted in each area every 2 months, from September 2006 to August 2007. Abundance of R. norvegicus and M. musculus was significantly higher in the shanty town than in the parkland. Abundance of both species showed significant differences between trapping sessions in both study sites. Both species showed a peak in abundance in summer in the parkland and also in autumn in the shanty town. Age structure of both species differed between summer–autumn and winter–spring in the shanty town. In the parkland, pregnant females of both species were only found in spring–summer. No significant differences were found in any of the reproductive parameters compared between the shanty town and the parkland. Our results suggest that the shanty town represents a favourable but not constant habitat for rodents throughout the year.

Hantaviruses and Their Hosts in Europe: Reservoirs Here and There, But Not Everywhere?

Five hantaviruses are known to circulate among rodents in Europe, and at least two among insectivores. Four (Dobrava, Saaremaa, Seoul, and Puumala [PUUV] viruses) are clearly associated with hemorrhagic fever with renal syndrome (HFRS). PUUV, the most common etiological agent of HFRS in Europe, is carried by the bank vole (Myodes glareolus), one of the most widespread and abundant mammal species in Europe. This host-virus system is among hantaviruses also the most studied one in Europe. However, HFRS incidence varies throughout the continent. The spatial as well as temporal variation in the occurrence of HFRS is linked to geographic differences in the population dynamics of the reservoir rodents in different biomes of Europe. While rodent abundance may follow mast seeding events in many parts of temperate Europe, in northern (N) Europe multiannual cycles in population density exist as the result of the interaction between rodent populations and specialist predator populations in a delayed density-dependent manner. The spatial distribution of hantaviruses further depends on parameters such as forest patch size and connectivity of the most suitable rodent habitats, and the conditions for the survival of the virus outside the host, as well as historical distribution patterns (phylogeographies) of hosts and viruses. In multiannually fluctuating populations of rodents, with population increases of great amplitude, one should expect a simultaneous build-up of recently hantavirus-infected (shedding) rodents. The increasing number of infectious, virus-shedding rodents leads to a rapid transmission of hantavirus across the rodent population, and to humans. Our review discusses these aspects for PUUV, the only European hantavirus for which there is a reasonable, yet still far from complete, ecological continental-wide understanding. We discuss how this information could translate to other European hantavirus-host systems, and where the most important questions lie for further research.

Complementary effects of disturbance by livestock and marmots on the spatial heterogeneity of vegetation and soil in a Mongolian steppe ecosystem

In the Mongolian steppes, livestock and burrowing rodents are the main animal modifiers of the habitat. Although grazing lands and rodent habitats overlap, the combined effects of livestock and rodent disturbance on spatial heterogeneity of plants and soil have rarely been evaluated. We established study plots at each of four sites: sites heavily grazed by livestock, with and without marmots, and ungrazed sites, with and without marmots. We subdivided each plot into quadrats to survey the plant species composition and soil nutrient properties, and calculated the spatial heterogeneity of vegetation at three spatial scales using non-metric multidimensional scaling analysis. We also calculated the coefficient of variance among the soil samples. The vegetation's spatial heterogeneity did not differ significantly between grazed and ungrazed plots; however, it was higher under marmot disturbance than in the absence of marmots at a fine scale, but lower under marmot disturbance at a coarse scale, irrespective of livestock grazing. At a fine scale, unique habitats were formed by each combination of livestock grazing (presence/absence) and marmots (presence/absence). In addition, the plant species composition in the grazed plots was distinct from that in the ungrazed plots at the coarser scale. The occurrence of degradation-indicator plant species depended on the presence of grazing rather than on the additive effect of grazing and marmots. Marmots increased the abundance of degradation-indicator species only in the ungrazed plots. Each herbivore group increased the spatial heterogeneity of soil nutrients at coarser scales, but these influences were lost when both herbivore groups coexisted. These results show that the ecological roles of livestock and marmots are complementary, not functionally equivalent. That is, livestock modified the overall vegetation composition, and thereby modified spatial heterogeneity at the landscape scale, whereas marmots modified spatial heterogeneity at the local scale. Proper manipulation of the livestock grazing regime can maintain species-rich communities without serious land degradation in the Mongolian steppe.

Rodent impact on establishment of direct-seeded Fagus sylvatica, Quercus robur and Quercus petraea on forest land

Seed predation by granivorous rodents constitutes a major problem during reforestation using direct seeding. Acorns or beech nuts were sown at 14 different sites in Denmark and southern Sweden, and seedling establishment was inventoried during the first three growing seasons. Around the time of sowing, rodents were either snap-trapped or live-trapped. At some sites, perches for raptors were installed, and at other sites, signs of predation were investigated or predation was monitored by camera surveillance. Granivorous rodents had a profound negative influence on sowings, and the removal of beech nuts occurred rapidly following sowing. Establishment of oak was better when surroundings consisted of mixed forests rather than broadleaved forests. Fewer rodents were caught, and establishment was better, in large reforestation areas. Rodent captures indicated that forest edges, slash piles and stone wall remains were suitable rodent microhabitats. Snap-trapping or raptor perches did not result in increased oak establishment. Neither sowing in summer nor increased seeding depth decreased predation by rodents on beech nuts. In conclusion, seeds need protection from rodents immediately at the time of sowing. Choosing large regeneration areas combined with removal of suitable rodent habitats seems to be a practical alternative for the development of successful strategies for direct seeding.

Evolutional and Geographical Relationships of Bartonella grahamii Isolates from Wild Rodents by Multi-locus Sequencing Analysis

To clarify the relationship between Bartonella grahamii strains and both the rodent host species and the geographic location of the rodent habitat, we have investigated 31 B. grahamii strains from ten rodent host species from Asia (Japan and China), North America (Canada and the USA), and Europe (Russia and the UK). On the basis of multi-locus sequencing analysis of 16S rRNA, ftsZ, gltA, groEL, ribC, and rpoB, the strains were classified into two large groups, an Asian group and an American/European group. In addition, the strains examined were clearly clustered according to the geographic locations where the rodents had been captured. In the phylogenetic analysis based on gltA, the Japanese strains were divided into two subgroups: one close to strains from China, and the other related to strains from Far Eastern Russia. Thus, these observations suggest that the B. grahamii strains distributed in Japanese rodents originated from two different geographic regions. In the American/European group, B. grahamii from the North American continent showed an ancestral lineage and strict host specificity; by contrast, European strains showed low host specificity. The phylogenetic analysis and host specificity of B. grahamii raise the possibility that B. grahamii strains originating in the North American continent were distributed to European countries by adapting to various rodent hosts.

Effects of predation by small rodents on the survival of beech (Fagus crenata) and oak (Quercus mongolica var. grosseserrata) seedlings with special reference to rodent habitat preference.

Effects of predation by small rodents on the survival of beech (Fagus crenata) and oak (Quercus mongolica var. grosseserrata) seedlings with special reference to rodent habitat preference.

Ecology and management of rodents in no‐till agriculture in Washington, USA

No-till farming is an important approach to sustainable agriculture because it can conserve soil and water resources. Unfortunately, rodent populations can thrive under no-till conditions because burrow systems are not disrupted by annual plowing and plant residues build-up on the surface, providing cover and insulation. This can result in substantial crop damage. We assessed rodent populations, habitat use, food habits, and crop damage in a no-till cropping system in Washington, USA. We also conducted preliminary trials of methods to reduce rodent populations and crop damage. In the fall, many more rodents were captured in fields with unharvested crops than in fields containing only plant stubble, suggesting that rodents leave fields after crop harvest, providing that suitable habitats are nearby, even when adequate cover is still available in harvested crop fields. By spring, the number of voles captured was much lower relative to fall. Despite this, capture rates were much higher in surrounding permanent grass areas than in crop (barley, wheat, pea) fields, suggesting that these grassy areas serve as refugia for rodents. Furthermore, the permanent grass cover type was the landscape variable most associated with rodent capture rates. In three winter pea fields, rodents removed 5-15% of the pea plants over winter. Examination of stomach contents revealed that voles mainly fed on grain plants in spring, but that their diet was more diversified in fall. Deer mice fed heavily on grain plants in both spring and fall, but also used insects as food. Metal barrier exclosures (9 m × 9 m), extending above and below ground, did not prevent access by rodents. Rodent populations in areas treated with zinc phosphide on grain were comparable to untreated areas 1 year after application of the rodenticide, perhaps because of immigration and recruitment, suggesting that baiting does not provide a long-term solution to rodent damage in no-till agricultural fields.

Poor Housing Quality Increases Risk of Rodent Infestation and Lassa Fever in Refugee Camps of Sierra Leone

Lassa fever, a viral hemorrhagic fever endemic in parts of West Africa, is a severe febrile illness transmitted to humans by the rodent Mastomys natalensis. To determine risk of Lassa fever in households in Sierra Leonean refugee camps, we analyzed the spatial relationships between households with a Lassa case and focal locations of potential rodent habitats. Quality and hygiene factors of households were assessed to determine possible risk factors for household rodent infestation and occurrence of Lassa fever. The odds to have a rat burrow were higher in case houses than in control houses (OR 24, 95% CI 6.0-93). Case houses scored significantly worse in the quality of housing and external hygiene. These findings suggest that risk of Lassa fever in refugee camps depends on individual housing quality and the hygiene of the immediate surrounding environment.

都市域の谷戸におけるネズミ類の生息動態と土地利用形態との関係

Yato (small valley with paddy field) in the urban area is important habitat for rural animals. Yato is a rural landscape made up of coppice forests, grasslands and farmlands. We discussed relations between the fauna and distribution of small rodents and land use of Yato landscape in the southwest Tama hills. As a result, Japanese large field mouse (Apodemus speciosus), house mouse (Mus musculus), brown rat (Rattus norvegicus) and harvest mouse (Micromys minutus) were observed by trappings and finding nests. Habitat utilization by these rodents were recognized as follows. 1. A. speciosus were dominant species in the survey area. They used all elements (coppice forest, farmland, grassland and paddy field) in Yato. It was considered that its main habitat was the coppice forest. 2. M. musculus utilized the farmland as its main habitat. 3. M. minutus were utilized the confined grassland. 4. R. norvegicus were captured only a few individuals at the farmland. When the mean range lengths were considered by the method of capture-recapture, it was clarified that A. speciosus had longer range lengths than any other species. It was suggested that landscape mosaics in Yato were important as rodent habitat. We concluded that managing land-use patterns of Yato is required to effectively conserve the rodents' diversity and their habitats.

From the recent lessons of the Malagasy foci towards a global understanding of the factors involved in plague reemergence

Re-emergence of human cases of plague after decades of silence does not necessarily mean that plague foci are re-emerging. Most often, Yersinia pestis bacteria have been maintained and circulating at low levels in the rodent populations. It seems therefore more appropriate to speak in terms of expansion or regression phases for sylvatic rodent plague foci and to reserve the term re-emergence for human cases. From the analysis of well-documented human plague cases in Madagascar, we underline the causes of re-emergence that can be generalized to most world foci, and can help define environments at risk where the threat of new emergence lurks. In all recent plague outbreaks, usually more than one risk factor was at the origin of the re-emergence. The reduction or discontinuance of surveillance and control, as well as poverty and insalubrity are the main factors in the re-emergence of human cases, allowing increased contacts with infected rodents and fleas. Environment changes (i.e. climatic changes, deforestation, urbanization) induce changes in flea and rodent populations by (i) extension of rodent habitats (for example by replacing forests by steppes or farmlands); (ii) modifications in population dynamics (possible outbreaks due to an increase of available food resources); but also, (iii) emergence of new vectors, reservoirs and new Y. pestis genotypes. Numerous and spontaneous genomic rearrangements occur at high frequencies in Y. pestis, which may confer selective advantages, enhancing the ability of Y. pestis to survive, to be transmitted to new hosts, and to colonize new environments. Therefore, any environmental change should be taken as a warning signal and active surveillance programs should be initiated.

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.

Competition, predation and interspecific synchrony in cyclic small mammal communities

Although competition and predation are considered to be among the most important biotic processes influencing the distribution and abundance of species in space and time, the relative and interactive roles of these processes in communities comprised of cyclically fluctuating populations of small mammals are not well known. We examined these processes in and among populations of field voles, sibling voles, bank voles and common shrews in western Finland, using spatially replicated trapping data collected four times a year during two vole cycles (1987–1990 and 1997–1999). Populations of the four species exhibited relatively strong interspecific temporal synchrony in their multiannual fluctuations. During peak phases, we observed slight deviations from close temporal synchrony: field vole densities peaked at least two months earlier than those of either sibling voles or bank voles, while densities of common shrews peaked even earlier. The growth rates of all four coexisting small mammal species were best explained by their own current densities. The growth rate of bank vole populations was negatively related to increasing densities of field voles in the increase phase of the vole cycle. Apart from this, no negative effects of interspecific density, direct or delayed, were observed among the vole species. The growth rates of common shrew populations were negatively related to increasing total rodent (including water voles and harvest mice) densities in the peak phase of the vole cycle. Sibling voles appeared not to be competitively superior to field voles on a population level, as neither of these Microtus voles increased disproportionately in abundance as total rodent density increased. We suggest that interspecific competition among the vole species may occur, but only briefly, during the autumn of peak years, when the total available amount of rodent habitat becomes markedly reduced following agricultural practices. Our results nonetheless indicate that interspecific competition is not a strong determinant of the structure of communities comprised of species exhibiting cyclic dynamics. We suggest that external factors, namely predation and shortage of food, limit densities of vole populations below levels where interspecific competition occurs. Common shrews, however, appear to suffer from asymmetric space competition with rodents at peak densities of voles; this may be viewed as a synchronizing effect.

Rodent Diversity and Land Use in Montebello, Chiapas, Mexico

We analyzed the abundance and diversity of Heteromyid and Murid rodents in the Lagos de Montebello National Park and adjacent areas, Chiapas, Mexico. We sampled three habitat types with different degrees of disturbance: pine-oak-liquidambar forest, ecotone and crop farming lands. Habitat types were defined considering characteristics such as heterogeneity, structural complexity and arboreal cover. We obtained ancillary habitat data considered important for small mammal requirements. Data on rodent communities were obtained by capture-mark-recapture between February and October 1996. We made 410 captures in 3820 trap-nights effort. Ten species were recorded, including one endemic with restricted distribution in Chiapas. Mouse diversity in the forest was significantly higher than within the farm lands. A Kendall correlation analysis showed positive relationship between rodent community species richness and habitat heterogeneity. Diversity of rodents was associated with the habitat complexity and structural elements, and negatively correlated with farming intensity. We found a high beta diversity and low similarity of the rodent communities in the three different habitats. Community composition strongly changed from the forest through the ecotone into the farm lands, with five species gained and seven species lost. The highest species richness was found in the ecotone; however, it showed a strong dominance of a single species that can convert into a plague of crops, and relatively low abundance of the other species. The pine-oak-liquidambar forest had the highest diversity indices, sheltering a particular rodent community within the study area, it therefore probably has the most important role in the conservation of the local biodiversity.

Life sciences flight hardware development for the International Space Station.

During the construction phase of the International Space Station (ISS), early flight opportunities have been identified (including designated Utilization Flights, UF) on which early science experiments may be performed. The focus of NASA's and other agencies' biological studies on the early flight opportunities is cell and molecular biology; with UF-1 scheduled to fly in fall 2001, followed by flights 8A and UF-3. Specific hardware is being developed to verify design concepts, e.g., the Avian Development Facility for incubation of small eggs and the Biomass Production System for plant cultivation. Other hardware concepts will utilize those early research opportunities onboard the ISS, e.g., an Incubator for sample cultivation, the European Modular Cultivation System for research with small plant systems, an Insect Habitat for support of insect species. Following the first Utilization Flights, additional equipment will be transported to the ISS to expand research opportunities and capabilities, e.g., a Cell Culture Unit, the Advanced Animal Habitat for rodents, an Aquatic Facility to support small fish and aquatic specimens, a Plant Research Unit for plant cultivation, and a specialized Egg Incubator for developmental biology studies. Host systems (Figure 1A, B: see text), e.g., a 2.5 m Centrifuge Rotor (g-levels from 0.01-g to 2-g) for direct comparisons between g and selectable g levels, the Life Sciences Glovebox for contained manipulations, and Habitat Holding Racks (Figure 1B: see text) will provide electrical power, communication links, and cooling to the habitats. Habitats will provide food, water, light, air and waste management as well as humidity and temperature control for a variety of research organisms. Operators on Earth and the crew on the ISS will be able to send commands to the laboratory equipment to monitor and control the environmental and experimental parameters inside specific habitats. Common laboratory equipment such as microscopes, cryo freezers, radiation dosimeters, and mass measurement devices are also currently in design stages by NASA and the ISS international partners.

Effects of introduction and exclusion of large herbivores on small rodent communities

In this study we analysed the effects of large herbivores on small rodent communities in different habitats using large herbivore exclosures. We studied the effects of three year grazing introduction by red deer (Cervus elaphus L.) in previously ungrazed pine and oak woodland and the exclusion of grazing by red deer, roe deer (Capreolus capreolus L.) and mouflon (Ovis ammon musimin L.) in formerly, heavily grazed pine woodland and heathland. At eight exclosure sites within each habitat type, small rodents were captured with live traps using trapping grids. At each trapping grid, seed plots of beechnuts (Fagus sylvatica L.) and acorns (Quercus robur L.) were placed to measure seed predation by rodents. Exclusion of grazing by large herbivores in formerly, heavily grazed habitats had a significant effect on small rodent communities. Inside exclosures higher densities of mainly wood mice (Apodemus sylvaticus L.) and field voles (Microtus agrestis L.) were captured. Introduction of grazing by red deer appeared to have no significant negative effects on small rodent communities. The seed predation intensity of beechnuts and acorns by small rodents was significantly higher in ungrazed situations, particularly in habitats that were excluded from grazing. The differences between grazing introduction and exclusion effects on small rodent communities can be explained by differences in vegetation structure development. The recovery of heavily browsed understory vegetation after large herbivore grazing exclusion proceeded faster than the understory degradation due to grazing introduction. Small rodents depend on structural rich vegetations mainly for shelter. We conclude that large herbivores can have significant effects on vegetation dynamics not only via direct plant consumption but also through indirect effects by reducing the habitat quality of small rodent habitats.