Small Mammal Community Dynamics Research Articles

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

Long-term Dynamics of Small Mammal Communities in the Period of Reduction of Copper Smelter Emissions: 2. β-Diversity

Long-term Dynamics of Small Mammal Communities in the Period of Reduction of Copper Smelter Emissions: 2. β-Diversity

Long-term Dynamics of Small Mammal Communities in the Period of Reduction of Copper Smelter Emissions: 1. Composition, Abundance, and Diversity

The long-term dynamics of the composition, total abundance, and diversity (α- and γ-diversity) of small mammal (SM) communities is analyzed in the vicinity of a large copper smelter during the periods of high (1990–1997), reduced (1998–2009), and almost terminated emissions (2010–2019). It is shown that the response of SM communities to pollution has not fundamentally changed over 30 observation years. An increase in pollution caused a significant reduction in the total abundance and α-diversity of communities and their dominance index in each of the three periods; at the same time, the γ-diversity remained similar in the background (13 species) and polluted zones (12 species). The reduction of emissions had no significant influence on the SM communities in the background (conditionally clean) zone: the species structure fluctuated insignificantly, the dominance structure did not change, and the increase in the animal abundance by the end of observations (owing to forest voles but not insectivores) was due to successional changes in the vegetation. The reduction of emissions led to a succession of dominants near the smelter and the trends of changes in abundance in this area differed from those observed in the buffer and impact zones (increase and no change, respectively). The increase in the abundance of species of different trophic groups (phytophages, granivores, and zoophages) in the moderately polluted (buffer) zone can be considered a symptom of the initial stages of recovery due to the improvement of habitat quality. Positive shifts in the SM community from the highly polluted (impact) zone are less distinct, being expressed only as an increase in the proportion of shrews.

Dynamics of small-mammal communities along an elevational gradient

Elevation is one of the most important natural gradients that is strongly shaping communities across relatively small areas. However, few studies have followed the temporal dynamics of elevational patterns, even in organisms for which population and community fluctuations have been extensively studied, such as rodents. Here we report the multiannual dynamics of small-mammal communities along an elevational gradient in the Southern Carpathians. During a 5-year survey, we conducted live-trapping in forested and shrubby habitats, at elevations between 820 and 2040 m. We used partial constrained multivariate analysis and mixed-effects models to test the effect of elevation, year, and their interaction. Community metrics differed significantly between even and odd years and temporal changes had stronger effect on small-mammal communities than elevation. The 2-year pattern of dynamics was especially marked in the yellow-necked field mouse (Apodemus flavicollis (Melchior, 1834)). Species abundance was predicted not only by year and elevation, but also by their interaction. The dominant rodent species, the bank vole (Myodes glareolus (Schreber, 1780)) and A. flavicollis, showed opposite annual patterns in relation to elevation, possibly as a strategy to avoid competition. Failure to consider the fluctuations in montane small-mammal communities may lead to wrong assessment of species’ state and distribution.

Long-term changes of small mammal communities in heterogenous landscapes of Central Europe

Long-term dynamics of small mammal communities are perennial themes in population ecology. However, comprehensive studies on the effect of environmental factors on population dynamics are still rare. Here, we aimed to analyze long-term data on Central European communities of small mammals occurring in two habitats that greatly differed in their structure, successional stages, and forest management. We found a richer community structure in young spruce plantations compared to mature European beech forests. In young spruce plantations, Myodes glareolus and Apodemus flavicollis abundances increased and Sorex araneus abundances decreased during the study period as a result of forest growth and management. Community structure in mature beech forests did not change significantly during the study period. Apodemus flavicollis and Myodes glareolus showed 3- and 5-year population cycles, respectively, and their abundances were simultaneously positively correlated with relative abundance of masts. Weather also played a role, while the effect of snow cover was pronounced only in mountain areas where it negatively affected Microtus agrestis and Sorex araneus abundances, temperature positively and rainfall negatively influenced Myodes glareolus and Apodemus flavicollis abundances across both studied habitats. Our findings document that a complex of environmental factors significantly affects the structure and dynamics of small mammal communities in Central Europe, and both local biotic and abiotic factors should be considered in future studies.

The presence of parasitic mites on small mammals in Algonquin Provincial Park, Ontario, Canada

Here we identify, for the first time, a generalist orange parasitic mite found on multiple small-mammal species in Algonquin Provincial Park, Ontario, Canada. Results from 18S rRNA sequencing suggest that these mites may belong to the family Trombiculidae (Acari: Trombidiformes), although morphological and additional genetic analyses are needed to confirm this identification. The presence of these mites was associated with lower body condition in North American red squirrels (Tamiasciurus hudsonicus (Erxleben, 1777)), suggesting that these mites may be a detriment to fitness in small mammals or are more successful when targeting individuals in poorer condition. A lack of sex-biased host infection, emergence dates outside of the host reproductive season, and stability of mite prevalence across study years indicate mite population dynamics may be driven predominantly by factors external from host status, such as climatic conditions or habitat preference. Future research should focus on providing additional reliable identification of these mites, as well as broadening our knowledge on their range, pathogenicity, and impact on small-mammal community dynamics.

Synchrony in small mammal community dynamics across a forested landscape

Long‐term studies at local scales indicate that fluctuations in abundance among trophically similar species are often temporally synchronized. Complementary studies on synchrony across larger spatial extents are less common, as are studies that investigate the subsequent impacts on community dynamics across the landscape. We investigate the impact of species population fluctuations on concordance in community dynamics for the small mammal fauna of the White Mountain National Forest, USA. Hierarchical open population models, which account for imperfect detection, were used to model abundance of the most common species at 108 sites over a three year period. Most species displayed individualistic responses of abundance to forest type and physiographic characteristics. However, among species, we found marked synchrony in population fluctuations across years, regardless of landscape affinities or trophic level. Across the region, this population synchrony led to high within‐year concordance of community composition and aggregate properties (e.g. richness and diversity) independent of forest type and low among‐year similarity in communities, even for years with similar species richness. Results suggest that extrinsic factors primarily drive abundance fluctuations and subsequently community dynamics, although local community assembly may be modified by species dispersal abilities and biotic interactions. Concordant community dynamics across space and over time may impact the stability of regional food webs and ecosystem functions.

Patch‐burn grazing increases habitat heterogeneity and biodiversity of small mammals in managed rangelands

AbstractHabitat heterogeneity is a key driver of biodiversity in many ecosystems. Wildlife inhabiting the native prairies of North America evolved in a heterogeneous mosaic of habitat conditions created by fire and grazing by native ungulates. Current rangeland management practices in the tallgrass prairie ecosystem evenly distribute fire and grazing across management units and promote homogeneous habitat conditions. Patch‐burn grazing is a rangeland management strategy that seeks to restore heterogeneity to rangelands via fire‐grazing interactions. Our 3.5‐year study tested the effects of patch‐burn grazing on habitat heterogeneity and small mammal community dynamics in the Flint Hills ecoregion of eastern Kansas. To study the ecological effects of patch‐burn grazing, we sampled habitat conditions and the small mammal community. We assessed habitat conditions once each growing season in a negative control that was annually burned and grazed, a positive control that was burned every four years and ungrazed, and within each of three units of a patch‐burn grazing experiment (PBG) managed with rotational fire. Habitat conditions were significantly different among treatments, and a principal components analysis showed that the patch‐burn grazing treatment had higher canopy cover of forbs and habitat heterogeneity than our two control units. To sample the small mammal community, we conducted monthly live trapping of small mammals on two randomly located trap grids in each of our two controls and three units of our PBG treatment. Small mammal diversity was significantly higher in the patch‐burn grazing treatment and in the positive control, vs. the negative control. Moreover, a canonical correspondence analysis showed that a fire‐grazing interaction was the major driver structuring small mammal communities. Patch‐burn grazing is an effective strategy for restoring heterogeneity to vegetative structure and composition, and can increase biodiversity of small mammals in managed rangelands in the tallgrass prairie ecosystem.

Small mammal community structure and dynamics in aridlands: overall patterns and contrasts with Southern Hemispheric systems

Aridlands offer unique opportunities to compare effects of history, evolution, and local geography on assemblage and dynamics of small mammal communities that have severe environmental constraints. Pioneering work in Northern Hemispheric aridlands resulted in paradigms that were assumed to be general. Because the evolutionary history and biogeography of Southern Hemispheric aridlands have been distinct, they offer unusual opportunities to test this assumption. We present 6 papers in this Special Feature that show that Southern Hemispheric aridlands have developed and evolved in many unique directions.

Long-Term Dynamics and Biodiversity Changes in Small Mammal Communities in a Mosaic of Agricultural and Forest Habitats

The long-term dynamics of small mammal communities inhabiting a mosaic of agricultural and forest habitats, that is, mixed forest, lakeside alderwood forest and arable land, set aside in the second period of the study, was analysed. No cyclicity was recorded in the numbers of the dominating species, that is, the bank vole (Myodes glareolus) and the yellow-necked mouse (Apodemus flavicollis). Fallowing of the arable land resulted in a decline in diversity and species richness of small mammals in the habitat mosaic under study. The greatest changes were recorded in the community inhabiting a narrow belt of spatially heterogeneous alderwood along the lakeshore. In this community, a considerable increase in the number of yellow-necked mice and a general increase in the dominance of forest species took place. We suggest that the fallowing of extensive arable lands, taking place in Poland for the last two decades, constitute an attractive source of food for small mammals and may lead to a considerable decline in small mammal species diversity within the landscape or even cause local extinctions in some species.

The interaction of disturbances and small mammal community dynamics in a lowland forest in Belize

1. Three floods (July 2000, August 2002, September 2003) and a hurricane (October 2001) that occurred in a lowland forest in the southern Maya Mountains of Belize presented an opportunity to evaluate the influence of these disturbances on the structure of a small mammal assemblage. 2. Four terrestrial and four primarily scansorial/arboreal species were trapped July 2000-March 2005 in six grids over 14 irregularly spaced trapping periods. 3. Community dynamics were characterized more by changes in species composition than changes in diversity. The dynamics were driven by species-specific variation in abundance, with changes in composition generally, but not exclusively, due to the occurrence or disappearance of species at low abundance. Despite the disturbances, species richness remained relatively constant. Evenness within the assemblage was consistently low, primarily as a result of dominance by one species, Heteromys desmarestianus. 4. Effects of flooding on community structure were direct but relatively brief (< 1 year), and varied with the duration and intensity of flooding. Effects from the hurricane were indirect but long-lasting and strongly related to severely reduced food resources. 5. This study suggests that long-term dynamics in the structure of many animal communities in the tropics often results from interactions between direct and indirect effects of disturbance. It also suggests that community resistance will depend on variation in disturbance type and regime, but resilience will be determined by the life-history characteristics of each species.

The dynamics of bioresources and activity of the paleolithic man, using the example of northwestern Altai Mountains

Long-term studies of living and fossil mammals of the Altai Mountains (= Gornyi Altai) revealed the pattern of the dynamics of small mammal communities in this region in the second half of the Pleistocene, in the Holocene, and the present time. The fossil fauna of the Anui River valley differs significantly from the modern one. The Pleistocene fauna of Paleolithic sites reflects a considerably more diverse biotopic situation and high landscape diversity compared with the present time. This diversity depended on a stronger role in the communities of steppe and highland elements. The influence of Paleolithic man on Late Pleistocene populations of ungulates and large predators is detected.

Landscape effects on the population dynamics of small mammal communities : a preliminary analysis of prey-resource variations

L’objectif de cette étude est d’estimer l’effet de la composition du paysage sur les variations de disponibilité en biomasse de micro-mammifères pour les prédateurs, à l’échelle sectorielle (n x 1 km2). Quatre sites d’étude représentatifs d’un gradient d’intensification agricole ont été choisis dans l’est de la France en fonction de la composition du paysage. Les fluctuations de biomasses de Microtus arvalis et Arvicola terrestris (espèces prairiales), de Clethrionomys glareolus et Apodemus sp. (espèces de milieux fermés) ont été suivies de 1992 à 1996 par méthodes indiciaires et piégeage. Les synchronies entre les populations de M. arvalis et celles de rongeurs de milieux fermés ont été recherchées. Les fluctuations de biomasse de M. arvalis et A. terrestris sont stables dans les sites où la proportion de prairie permanente est la plus faible. Les populations de M. arvalis présentent les plus larges amplitudes de variation de biomasse et les déclins les plus prononcés dans les sites où la proportion de prairie permanente sur la surface agricole est supérieure à 50 %. Les populations d’A. terrestris ne sont instables que dans un site, là où la proportion de prairie permanente sur surface agricole est supérieure à 85 %. Les déclins de populations de rongeurs de milieux fermés (Clethrionomys glareolus et Apodemus sp.) sont concomitants de ceux de M. arvalis dans les sites à fortes variations de biomasse de cette dernière espèce. Ces résultats suggèrent deux types de fonctionnement, en terme de variation de disponibilité en proies pour les prédateurs : (i) stable dans les paysages à faible proportion de prairie permanente, et (ii) instable, avec des déclins prononcés et rapides des populations d’espèces prairiales, entraînant des déclins synchrones du peuplement de micro-mammifères étudié, dans les paysages à forte proportion de prairie permanente. Aucune synchronie dans les dynamiques de population de ces micro-mammifères n’est observée entre les sites d’étude, éloignés de quelques dizaines de kilomètres seulement.

Prospective seroepidemiology of hantaviruses and population dynamics of small mammal communities of Baltimore, Maryland.

We used a prospective seroepidemiological study, in conjunction with a mark-release-recapture protocol, to investigate the transmission of hantaviruses in four rodent species from Baltimore, Maryland, from June 1984 to June 1986. A total of 1,208 captures of 762 rodents provided 984 individual blood samples. The antibody prevalence, as determined by frequency of reciprocal indirect fluorescent antibody (IFA) titers greater than or equal to 32, was 33.9% in rats (Rattus norvegicus, n = 466), 28.3% in meadow voles (Microtus pennsylvanicus, n = 67), 1.4% in house mice (Mus musculus, n = 146), and 1.2% in white-footed mice (Peromyscus leucopus, n = 83). Populations of all rodents were maximal during the fall and winter months, but population trends were not clearly associated with periods of virus transmission. The mean incidence of seroconversion to a Hantavirus for rats was 12.06/100 rats/month, but incidence rates could not be established for other species. Rats which seroconverted were generally sexually mature animals, and there was evidence of transmission throughout the year. Animals which seroconverted to a Hantavirus achieved high IFA titers, and remained seropositive for the duration of the study.