Small Mammal Community Structure Research Articles

Gastrointestinal morphology is an effective functional dietary proxy that predicts small mammal community structure.

The availability and quality of food resources can alter the intensity of competition and predation pressure within communities. Understanding species capacity to respond to global change-driven shifts in resource distribution is therefore crucial for biodiversity conservation. Small mammal communities are often structured by competition for food resources, but understanding and monitoring these processes are currently hindered by lack of functional dietary trait information in these hard-to-sample systems. In this study, we collected a comprehensive suite of gastrointestinal (GI) measurements from 26 small mammal species (including some never reported), compared them with more traditional craniodental traits in predicting dietary guild, and used them in a novel way to understand how diet structures 22 small mammal communities across the Appalachian Mountains of eastern North America. As predicted, we found GI traits to be effective dietary trait proxies; they were equally or more accurate than craniodental proportions in predicting the dietary guild of individual species. Furthermore, at the community level, we found that both the mean and functional dispersion of GI length were positively correlated with latitude and measures of temperature seasonality. Our results indicate that small mammal communities in more seasonal environments are filtered to include species with longer GI tracts (on average) as well as those that can partition food resources more finely, as expected based on the lower productivity of these regions. Conversely, communities in less seasonal environments display functional redundancy from the addition of species with short to intermediate GI lengths. Proportions of the GI tract represent novel dietary traits that can illuminate community assembly processes across regional environmental gradients and in the face of changing timing and availability of resources.

Small mammal diversity and community structure exhibit congruent hump-shaped patterns along a subtropical elevational gradient

Incomplete elevational sampling in studies of biodiversity and community assembly along elevational gradients can result in inconsistent findings and potentially inaccurate conclusions about assembly mechanisms. In this study, we conducted extensive sampling of small mammals over a 3200 m elevational gradient on Xiling Snow Mountain, Southwestern China. We integrated functional and phylogenetic diversity to determine the mechanisms structuring small mammal assemblages. Our findings indicate that taxonomic, functional, and phylogenetic diversity, along with all species richness-corrected indices of functional and phylogenetic diversity, exhibit similar hump-shaped patterns. Our results suggest that environmental filtering plays a considerable role in structuring small mammal communities at low and high elevations, while competitive exclusion governs the assembly processes at middle elevations. Human footprint, Normalized Difference Vegetation Index, precipitation seasonality and potential evapotranspiration are key drivers of small mammal diversity and community structure along elevational gradients. In summary, our study provides evidence that phylogenetic diversity is a robust surrogate for functional diversity, and challenges the recent large-scale studies that advocate a linear relationship between small mammal assembly process and elevation. We emphasize the importance of continuously documenting general patterns of small mammal diversity across entire elevational gradients in future studies.

The nature of vegetation cover and small mammal community structure (on the example of Nizhny Novgorod)

The spatial distribution of Apodemus species (yellow-necked, field, and small forest mice) was studied on the example of the protected area «Oak forest of National Research Lobachevsky State University of Nizhny Novgorod Botanical Garden». Twelve plant associations with non-moral character and representing derivatives of the indigenous type of vegetation were studied. Environmental conditions assessed by the Ellenberg phytoindication method affect the distribution of small mammals in space indirectly. The nature of vegetation cover is more significant. When projective cover increases, the abundance of both small woodland and field mice increases. The strategy of Apodemus agrarius appears to be similar to that of Apodemus uralensis, a species that shows stenobiontic traits in the studied PA. At the same time, insignificant anthropogenic load, a marker of which is the presence of Urtica dioica ruderal species, leads to an increase in the mosaic of vegetation cover, which has a positive effect on the abundance of these small mammal species. A moderate increase in the Berger-Parker dominance index for vegetation cover is positively associated with the confinement of micromammals. In addition, in the conditions of the recreational zone of the upland part of N. Novgorod, Apodemus agrarius prefers areas of old-growth broadleaved forest, not showing the features of anthropophily.

Small mammal assemblages in heterogeneous landscapes at the Southern tip of Italian peninsula evidence clear eco-biogeographic patterns

We investigated the frequencies of sympatric small mammal species in 12 habitat-types located in the extreme south of the Italian peninsula (Calabria) using trapping techniques. Ten species were detected with Apodemus sylvaticus, the most abundant species. The assemblages of small mammal species recorded in the 12 selected habitat types revealed clear ecological and biogeographical patterns in the extreme southern tip of the Italian peninsula. Ecologically, we observed a clear dissimilarity between a guild of species linked to thermo-xerophilous habitat types and a comparable guild of mesophilous species linked to forest and sciaphilous habitat types. The differences among communities inhabiting in different habitat types also emerged in rarefaction curves, DCA analysis and Whittaker plots. Thus, all these sets of analyses were consistent in their interpretation of the variation of small mammal community structure along the gradient (β-diversity) among habitat types. From a biogeographical point of view, this is an apparent expression of a clear North–South gradient pattern that was already observed at the species level with Calabria being characterized by a strong impoverishment in species’ richness and diversity (“peninsula effect”). However, this rationale has been based so far on indirect data of small mammals preyed upon and recorded in owl’s pellets: the fact that a similar pattern was obtained also using small mammals recorded by traps indicates that the results were robust and generalizable. Ecological factors at the local scale and biogeographical factors at the peninsular scale could explain the community patterns that we observed in the present study.

The Diversity of Small Mammals along a Large River Valley Revealed from Pellets of Tawny Owl Strix aluco.

The Vistula River is one of the largest European semi-natural rivers of high ecological value that functions as an ecological corridor. To assess the structure of small mammal communities along the Vistula River, an analysis of the diet of an opportunistic predator, the tawny owl Strix aluco, was used. A total of 6355 individuals of 19 species were found, including 5 soricomorph species, 12 rodents, 1 carnivore, and 1 bat species. Tawny owls most frequently caught Apodemus agrarius, Clethrionomys glareolus, Apodemus flavicollis, and Microtus arvalis. Rodents dominated small mammal communities (90%), followed by soricomorphs (8%), and the share of Chiroptera was significant (2%). Using Ward's method in cluster analysis, three clusters of sites with similar mammal communities were identified. The cluster that included 17 study sites with the dominance of agriculture habitats was inhabited by diverse mammal communities with a high number of species. In the cluster composed of three suburban forest sites, mammal communities had the lowest diversity, although the high species richness and the highest shares of the forest species (A. flavicollis, C. glareolus, and Nyctalus noctula). Mammal communities in the cluster were composed of three urban sites were dominated by A. agrarius and M. arvalis. The study indicates the high species richness of small mammals in floodplains of the Vistula River and the adjacent areas in central Poland. The floodplain offers suitable habitats for species associated with forests, water bodies, agricultural land, and developed areas. The data collected confirms earlier model predictions about the presence of well-connected local populations of forest mammals along the Vistula River.

Peculiarities of the Dynamics and Structure of Small Mammal Communities at High Latitudes

Peculiarities of the Dynamics and Structure of Small Mammal Communities at High Latitudes

Low impact of forest conversion on biodiversity: Evidence from small mammals in contrasting forests of Mt. Liangshan

AbstractSecondary and plantation forests are the main alternative forests remaining after the deforestation of primary forests. Understanding the conservation value of secondary and plantation forests is important for biological conservation. To explore the impact of forest conversion on biodiversity, we compared multiple diversity metrics (taxonomic, phylogenetic, and functional diversity) and community structure of small mammals in the primary, secondary, and plantation forests in Mt. Liangshan, Sichuan Province, China. Three field surveys were conducted in each of the three forest types to characterize local small mammal assemblages from 2017 to 2020. We found that the taxonomic, phylogenetic, and functional diversity of small mammals in the three forest types were similar at the landscape scale, while all diversity metrics were lowest in the plantation forest and highest in the primary forests at the site scale. The community structure analysis showed that habitat filtering was the dominant process driving the assembly of small mammal communities across the three forest types, and there was no statistically significant difference in small mammal community structure among the three forest types. Our results indicated that secondary and plantation forests in the nature reserves, adjacent to the primary forest and exposed to little human disturbance, also can provide important habitats for small mammals.

Impact of habitat variation and human activities on small mammal community structure and diversity in Diannan Town, Jianchuan County, Yunnan

Impact of habitat variation and human activities on small mammal community structure and diversity in Diannan Town, Jianchuan County, Yunnan

Small Mammal Diversity Changes in a Baltic Country, 1975-2021: A Review.

The structure and diversity of small mammal (SM) communities over the long term may show the influences of climate change, landscape changes and local disturbances. We review published data regarding SM trapping and owl pellet analysis from Lithuania (the most southerly of the three Baltic States, Northern Europe), covering the period 1975-2021. Over decades, we analysed trends in the diversity of SM communities and the proportions of species and proportions of trophic groups. The large increase in granivores, from 6.9% in 1975-1980 to 45.4% in 2011-2020 and 54.7% in 2021, coincided with a decrease in omnivores and insectivores. The proportion of herbivores increased less notably. At the species level, significant decreases in the proportions of M. arvalis, C. glareolus and S. araneus were accompanied by notable increases in the proportions of A. flavicollis and A. agrarius, the latter from 1.0% in 1975-1980 to 25.3% in 2021. Concluding, two periods were identified, specifically before the 1990s and subsequently. In the second period, in the aftermath of land-use changes within the country in 1990, diversity increased, and dominance decreased, a situation that has not subsequently changed. Not excluding the concomitant effects of climate change, we relate these patterns to the alterations in habitat and anthropogenic impact.

The loss of vegetation cover has distinct but short-term impact on multiple vertebrate taxa in a grassland ecosystem

Vegetation cover in grasslands typically fluctuates over time, for example, declining with grazing and disappearing entirely with burning. This temporal change in vegetation cover may impact the composition of vertebrate communities by altering habitats or perceived predation pressure. We manipulated vegetation cover in a high-elevation (ca. 1240–1500 m above sea level) grassland ecosystem and measured its effect on the community structure of birds and small mammals using a Before-After-Control-Impact study design. We established 12 plots (each plot 100 × 100 m) at Telperion Nature Reserve, Mpumalanga, South Africa, which were assigned to three treatments: mowed with cut grass left in situ (mowed-litter), mowed with cut grass cleared (mowed-cleared), and non-mowed (control). We sampled birds and small mammals over three sampling periods: before the treatment (August 2019), immediately after the treatment (October 2019), and three months after treatment (January 2020). We used point counts and Sherman live traps to surveys birds and small mammals, respectively. We observed a total of 2801 individuals of 38 species of birds and 98 individuals of eight species of small mammals. Species richness and diversity of small mammals and birds was significantly higher in the non-mowed plots compared with the mowed plots. Birds also showed differences in community composition in mowed and non-mowed treatments immediately after mowing but these differences disappeared three months after mowing, whereas small mammal composition did not differ before and after mowing. The best performing generalized additive model showed that vegetation biomass had a significant positive influence on bird species richness but not rodents. On the other hand, diversity of both taxa was significantly influenced by grass biomass. Our study suggests that loss of vegetation cover in grasslands has significant short-term effects on birds and small mammals, but that these faunal communities rapidly return to pre-loss conditions within a few months. Hence controlled vegetation removal (e.g. mowing) could be considered an appropriate tool for managing these high-elevation grasslands.

Terrestrial small mammal community structure in a relic forest and anthropogenic habitats in Man region, Western Côte d’Ivoire

Terrestrial small mammals play important ecological roles in tropical ecosystems. They are regularly used to measure the level of habitat disturbance. This study aimed to determine the impacts of human activities on the species composition and relative abundance of terrestrial small mammal communities in Man region. Four types of habitats, including a relic forest, a […]

Population and Community Responses of Small Mammals to Single-tree Selection Harvest in Laurentian Hardwood Forests

Small mammals are ubiquitous members of vertebrate communities that are sensitive to habitat change. In the Great Lakes region of North America, small mammal communities have changed rapidly, but experimental tests of potential mechanisms are lacking. Using a before-after, control-treatment design, we quantified the response of small mammals to single-tree selection harvest in Laurentian hardwood forests of Wisconsin, United States. We documented changes in forest structure and small mammal abundance, species diversity, and community similarity from silvicultural treatment. Treatment reduced tree density and canopy cover and increased mean tree diameter, woody stem density, variation in woody stem density, and volume of coarse woody debris. Peromyscus and northern short-tailed shrews (Blarina brevicauda) were dominant community members across treatments and years. White-footed mice (P. leucopus) outnumbered woodland deer mice (P. maniculatus gracilis) before treatment, but declined by almost fifty percent after treatment; deer mice and total rodent (i.e., Rodentia) abundances were unchanged. Small mammal species diversity increased twofold following treatment. Our experiment identified species-specific responses within Peromyscus to timber harvest: white-footed mice, the numerically dominant and generalist species, were most sensitive to habitat change, and their response produced cascading effects to small mammal community structure. Future experiments should assess these small mammal responses in a multi-year framework and quantify their effects on the broader vertebrate community.

Human Disturbance and Geometric Constraints Drive Small Mammal Diversity and Community Structure along an Elevational Gradient in Eastern China.

Simple SummaryBiodiversity patterns and mechanisms along elevational gradients have long been the focus of conservation research. However, few studies have been conducted in mountainous areas of eastern China, especially for small mammals. In this study, we used a standard sampling method to survey small mammals along the gradient of Qingliang Mountain in eastern China and analyzed the patterns and mechanisms of diversity and community structure. We found inconsistencies between different diversity dimensions. Functional and phylogenetic structures were mainly clustered but showed opposite elevation patterns. Human disturbance and MDE were the main drivers of the diversity patterns, but with contrasting effects on different dimensions. These findings emphasize the importance of a multiple dimensions approach to biodiversity conservation and call for increased conservation efforts in the low and middle elevation regions.Understanding the mechanisms influencing patterns and processes of biological diversity is critical to protecting biodiversity, particularly in species-rich ecosystems such as mountains. Even so, there is limited knowledge of biodiversity patterns and processes in the mountains of eastern China, especially about small mammals. In this study, we examined the taxonomic, functional, and phylogenetic diversity of small mammal distribution and community structure along the elevational gradient of Qingliang Mountain, eastern China. We then evaluated how they are influenced by space (area and mid-domain effect (MDE)), environment (temperature, precipitation, and normalized difference vegetation index (NDVI)), and human disturbance. The results showed hump-shaped patterns of taxonomic and phylogenetic diversity along elevation gradients, peaking at 1000 m, unlike functional diversity, which peaked at lower elevations (600 m). The mean pairwise distance and mean nearest taxon distance of functional and phylogenetic variance (MFD and MPD, respectively) were also incongruent. The MFD and MPD showed hump-shaped patterns along elevations; however, unlike MFD, which peaked at lower elevations (600 m), MPD peaked at higher elevations (1200 m). The mean nearest functional taxon distance (MNFD) decreased, while the mean nearest phylogenetic taxon distance (MNTD) increased along the elevation gradient. The higher elevations were functionally more clustered, while the lower elevations were phylogenetically more clustered, suggesting that environmental filtering for traits was stronger at higher elevations. In comparison, phylogenetic conservatism of ecological niches had a stronger influence at lower elevations. The diversity and community structure indices were inconsistently explained, with human disturbance and MDE accounting for the biggest proportions of the model-explained variances. Overall, the results confirm that environmental filtering and human disturbance significantly influence small mammals’ diversity and community structure. These findings also emphasize the need for increased conservation efforts in the middle and lower elevation regions of Qingliang Mountain.

Postfire salvage logging alters impacts of recent wildfire on small mammal communities in summer

Abstract Wildfire is a natural ecosystem disturbance in forests in North America, yet fires are often at odds with human activity and affect the timber supply. Postfire salvage logging is common practice globally, but the impacts of salvage logging on wildlife, especially small mammal communities, remain unclear. We livetrapped small mammals to determine their population responses to wildfire and postfire salvage logging in central British Columbia, Canada. Postfire regenerating forest provided habitat for deer mice (Peromyscus maniculatus), southern red-backed voles (Myodes gapperi), and meadow voles (Microtus pennsylvanicus). Postfire salvage logging significantly reduced tree basal area and changed small mammal community structure by reducing southern red-backed vole populations and supporting mainly deer mice, a generalist species. Given the large scale and intensity of postfire salvage logging operations across the province, salvage logging has the potential to decrease vole populations and change small mammal communities across the province.

Small mammal responses to fire severity mediated by vegetation characteristics and species traits.

The frequency of large, high‐severity “mega‐fires” has increased in recent decades, with numerous consequences for forest ecosystems. In particular, small mammal communities are vulnerable to post‐fire shifts in resource availability and play critical roles in forest ecosystems. Inconsistencies in previous observations of small mammal community responses to fire severity underscore the importance of examining mechanisms regulating the effects of fire severity on post‐fire recovery of small mammal communities. We compared small mammal abundance, diversity, and community structure among habitats that burned at different severities, and used vegetation characteristics and small mammal functional traits to predict community responses to fire severity three years after one mega‐fire in the Sierra Nevada, California. Using a model‐based fourth‐corner analysis, we examined how interactions between vegetation variables and small mammal traits associated with their resource use were associated with post‐fire small mammal community structure among fire severity categories. Small mammal abundance was similar across fire severity categories, but diversity decreased and community structure shifted as fire severity increased. Differences in small mammal communities were large only between unburned and high‐severity sites. Three highly correlated fire‐dependent vegetation variables affected by fire and the volume of soft coarse woody debris were associated with small mammal community structures. Furthermore, we found that interactions between vegetation variables and three small mammal traits (feeding guild, primary foraging mode, and primary nesting habit) predicted community structure across fire severity categories. We concluded that resource use was important in regulating small mammal recovery after the fire because vegetation provided required resources to small mammals as determined by their functional traits. Given the mechanistic nature of our analyses, these results may be applicable to other fire‐prone forest systems, although it will be important to conduct studies across large biogeographic regions and over long post‐fire time periods to assess generality.

Structure and dynamics of small mammal communities in the valley biotopes at the confluence of the Ob and Irtysh rivers

Structure and dynamics of small mammal communities in the valley biotopes at the confluence of the Ob and Irtysh rivers

Население мелких млекопитающих подтайги Южного Зауралья

On the basis of materials obtained using two generally accepted counting methods, data on the species composition of small mammals, the ratio of background and dominant species, the total abundance in the main groups of biotopes of the South Trans-Ural region are presented. The differences in the community structure of small mammals in the subtaiga and forest-steppe sub-zone of the South Trans-Ural region have been analysed. The paper discusses materials on the community of small mammals in the sub-taiga of the South Trans-Ural region. A brief history of the study of this group of animals is reviewed. The use of two counting methods (the ditch with pitfalls and trap-lines) allowed the most complete identification of the species composition of insectivores and rodents in the sub-taiga of the South Trans-Ural region in 2021. In terms of species, the ditch with pitfalls were more effective, with 17 species identified; trap-lines counted 13 species. The abundance of animals in 2021 was very low. In our opinion, was determined by the abnormally hot spring and summer period. On average, only rare and very rare species have been recorded in the snap-trap counts in the study area. Numerous species were absent in the average meaning regardless of the method of capture. The core of small mammals of the sub-taiga of the South Trans-Ural region consisted of species typical of humid habitats and small-leaved forests, such as the Laxmann's shrew Sorex caecutiens, common shrew S. araneus and Eurasian pygmy shrew S. minutus rodents, as well as the common vole Microtus arvalis and harvest mouse Micromys minutus (surveys using the ditch with pitfalls). The common shrew was predominant in the snap-trap counts, accounting for about 45% of the total abundance of all animals recorded. In pine forests with poor productivity and in open spaces, the total abundance of insectivores and rodents is lowest. The species composition of small mammals of the sub-taiga and forest-steppe subzone of the South Trans-Ural region are largely similar (83% of the total species). Specific features of the taiga subzone were determined by the taiga shrew Sorex isodon and Siberian chipmunk Eutamias sibiricus, unusual for the forest-steppe and herb-bunchgrass steppe subzone of the South Trans-Ural region. A characteristic feature of the sub-taiga of the South Trans-Ural region is a specific proportion of the northern red-backed vole Myodes rutilus and European bank vole M. glareolus, their abundance is comparable, or the M. glareolus predominates, which is not observed in the forest-steppe. In the sub-taiga, in the surveys using ditch with pitfalls among insectivores and rodents, the Laxmann's shrew prevailed, its share was approximately one fourth of all recorded animals, although in general the community of small mammals is polydominant, in contrast to the surveys using the trap-line method, where one species dominated – the common shrew. In 2021 (sub-taiga) as well as in 2020 (forest-steppe) the territory of the South TransUral region was characterized by a deep depression of water vole Arvicola amphibius numbers, which was completely absent in the counts.

Temporal and spatial changes in small mammal communities in a disturbed mountain forest

Abstract In 2005–2016, we investigated a secondary succession of small mammal communities in forest ecosystems in High Tatras (Slovakia) disturbed by windstorm and fire. This long-term ecological study confirmed the occurrence of significant temporal and spatial changes in species composition and number of dominant small mammal species. A comparison between disturbed and undisturbed plots indicated notable differences in species richness and abundance. The gradations of dominant small mammal species in disturbed habitats were asynchronous and showed a wider range of amplitude than in the undisturbed plots. An analysis of the temporal and spatial changes in the structure of small mammal communities in relation to selected environmental gradients confirmed the statistically significant effect of secondary succession on species composition, abundance, and exchange in forest ecosystems in the High Tatra Mountains following a disturbance.

Winners and Losers: How Woody Encroachment Is Changing the Small Mammal Community Structure in a Neotropical Savanna

Years of fire suppression, decreases in herbivores, and global climate change have led to shifts in savannas worldwide. Natural open vegetation such as grasslands and shrublands is increasing in wood density, but the effects for small mammals are not well understood. While most of the mammal studies from the Brazilian Cerrado are concentrated in the core area of this large Neotropical savanna, its southern portions are suffering from biome shifting through woody encroachment. Herein, we surveyed a small mammal community from the southeastern boundary of Cerrado (Santa Bárbara Ecological Station) and evaluated the micro and macro environmental variables shaping community structure in order to investigate how the woody encroachment in the last 15 years may have influenced this assemblage. We recorded 17 species of marsupials and rodents along five distinct habitats in a gradient from grasslands to woodlands. Although richness was not affected by microhabitat variables, total and relative abundance varied according to habitat type and in relation to herbaceous, shrub, and tree density. Rodents such as Calomys tener and Clyomys laticeps were positively affected by increasing herb cover, Cerradomys scotti and Oligoryzomys nigripes by shrub cover, while the marsupial Didelphis albiventris had higher association with increasing tree cover. We detected an increase of 27.4% in vegetation density (EVI) between 2003 and 2018 in our study site, and this woody encroachment negatively affected the abundance of some small mammals. The open-area specialists Cryptonanus chacoensis and C. scotti had a decrease in abundance, while D. albiventris and O. nigripes were favored by woody encroachment. Our data suggest that woody encroachment is shifting community composition: small mammals often associated with grasslands and open savannas are likely to be negatively affected by woody encroachment; while species that rely on tree-covered habitats are likely to benefit from an increasing woody landscape. Therefore, forest-dwellers are gradually replacing open-vegetation inhabitants. Active management of open formations (e.g., with prescribed burning) may be needed to maintain Cerrado biodiversity, especially considering the open-area endemics.

Impact of technogenic transformation of northern taiga land-scapes on mammalian population

Studies of the mammalian population in the area of operation of a large mining enterprise located in the northern taiga subzone of Yakutia have been conducted. A total of 2,334 cone-days and 3,000 trap-days are accumulated, post-hunting censuses of game species are taken. The mammalian fauna in the area affected by Udachninsky GOK is represented by 27 species. The negative impact of the mining enterprise on game species of mammals is manifested as an affected zone, for fur animals its width is 1.5–4.4 km, for the moose it is over 20 km. The study area is crossed by migration routes of the wild reindeer, and the presence of an industrial facility is a permanent threat to the well-being of the Lena-Olenek population of the species. The region is characterized by low abundance levels of small mammals even outside the anthropogenically affected areas. In technogenically transformed biotopes a decrease in capture rate and biodiversity parameters is registered, especially in open biotopes. In the forest stations forest species are being replaced by herbivorous inhabitants of open areas, which results in observable changes in the community structure. On the whole, the impact of the technogenic transformation of landscapes by the mining industry is manifested in redistribution of economically valuable species across the territory and a decrease in abundance and changes in the community structure of small mammals in the affected area.