Composition Of Small Mammal Communities Research Articles

Long-term impact of agricultural practices on the diversity of small mammal communities: a case study based on owl pellets.

Small mammals have been seldom used as indicators of biodiversity responses to environmental changes, probably because their long-term population trend in a given area is not easy to monitor. To assess the impact of agricultural intensification in a protected area of northern Italy, we compared the composition of its small mammal communities, as assessed in 1994-1995 and 2015-2016 by the analysis of owl pellets (N = 265 and 302, respectively), which provides an effective and affordable method for assessing changes in the diversity and structure of small mammal assemblages over time. We recorded a sharp reduction in the frequency of occurrence of shrews (Sorex spp. and Crocidura spp.), which were replaced by generalist/anthropophilic rats (Rattus norvegicus) and house mice (Mus domesticus). Overall richness and diversity of the community varied only slightly, while trophic level and functional diversity indices clearly reflected the decline of the predator-level fraction of the community. We could reliably exclude both broad-scale land use- and climate changes as drivers of variation in the composition of small mammal communities and ascribe the decline of insectivores to changes in agricultural practices, namely the increase in cover of maize fields and spread of both herbicides and insecticides. Our results are consistent with the general opinion that crop specialization and increasing chemical inputs reduce the diversity and abundance of invertebrate prey, with bottom-up effects on higher trophic levels.

Traits reveal how habitat‐quality gradients structure small mammal communities in a fragmented tropical landscape

AbstractUnderstanding the relationships among community structure, vegetation structure and availability of food resources are a key to unravelling the ecological processes that structure biological communities. In this study, we tested (i) whether the composition of small mammal communities changed across gradients in habitat quality in tropical forest fragments, and (ii) whether any observed change could be explained by the functional traits of species. We sampled 24 trapping grids in fragments of semi‐deciduous forest, in each of two 6‐month periods. We considered each trapping grid as a sampling unit, for which we collected three datasets: an environmental matrix (vegetation structure and food resource availability), the abundance of small mammal species (community structure) and a matrix of functional traits (ecological and morphological traits which express tolerance to habitat disturbance and trophic guild). We used an RLQ approach to evaluate the association between traits and environmental gradients. Forest‐specialist and scansorial–arboreal species were associated with more complex habitat that had greater litter and canopy cover and more fallen logs. In relation to trophic guilds, granivore (fruit seeds), insectivorous and omnivorous species were also associated with higher complexity habitat, while frugivores were associated with shrub cover and availability of fruits. We conclude that functional traits (habitat use, use of vertical strata and diet) provide valuable insights into the distribution of small mammals along gradients of habitat quality in tropical forest fragments. We highlight that communities studies in fragmented landscapes should investigate the different components of biodiversity not only in landscape‐scale but also in habitat scale.Abstract in Portuguese is available with online material.

The impact of Acacia saligna and the loss of mobile dunes on rodent populations: a case study in the Ashdod-Nizzanim sands in Israel

The Mediterranean coastal dune habitat of Israel is diminishing rapidly, mostly due to massive urbanization, changes in habitat characteristics caused by dune stabilization and the presence of Acacia saligna, an invasive species brought to Israel for the purpose of dune stabilization. In this study we document the effect of sand stabilization on the composition of small mammal communities in the Ashdod-Nizzanim sands, Israel. We analyzed differences in species diversity and abundance for species of rodents in four types of habitat: unstable (mobile) sand dune, semi-stabilized dune, inter-dune depression and a plot of the invasive Acacia saligna. Rodent communities were found to undergo gradual changes concurrently with the stabilization of the sands. The mobile dune was the only habitat in which the strict psammophiles Jaculus jaculus and Gerbillus pyramidum were captured in abundance. No species commensal with human were captured neither in the mobile nor in the semi-stabilized dunes. However, in the inter-dune depression there was quite a large representation of Mus musculus, a rodent commensal with humans. The Acacia saligna plot had the lowest number of captures and the lowest rodent biomass calculated, with Mus musculus composing nearly half of the captures. The results of this study demonstrate that stabilization of the sands in Ashdod-Nizzanim area is associated with the disappearance of psammophile rodents and the appearance of species commensal with humans. In order to preserve the habitat for psammophile rodents, measures should be taken to halt the spread of acacia and the continuing stabilization of the sands.

Changes of small mammal communities with the altitude gradient

The influence of altitude gradient on the animal communities in the Eastern Tatra Mountains of Slovakia has never been studied. There are some rare, endemic and relict animal species and even a group of small terrestrial mammals native to the Tatra Mountains. Between 2009 and 2014, research was conducted on the impact of altitude gradient on the species richness, abundance and composition of small mammal communities in the Eastern Tatras. In total, more than 16 species were trapped, including snow voles, tatra voles and alpine shrews, three species endemic to the Carpathian Mountains. The species richness of small mammals declined at higher elevations. The endemic alpine shrew was found at altitudes of 914 and 1007 m above sea level, while tatra voles were recorded almost along the entire gradient studied. Snow voles ranged only above the tree line at altitudes of 1574 to 1775 m, in the Rock slope habitat. On the other hand, generalists colonised various parts of the gradient at different altitudes, while specialists were bound to specific habitats whose presence was limited by altitude. The composition of small mammal communities evidently and significantly varied with rising elevation and with the biotope type in the area under observation. Our results suggest that the composition of the community reflects changes in environmental conditions and the biological limits of the particular small mammal species in the altitude gradient as well as the combination of neighbouring habitats and the resources they provide.

Mow the Grass at the Mouse's Peril: Diversity of Small Mammals in Commercial Fruit Farms.

Simple SummaryFor the first time in the Baltic countries, small mammal communities were evaluated in commercial orchards and berry plantations to test for the influence of crop type and intensity of agricultural practices. Out of ten species registered in the fruit farms, the most dominant were common vole and striped field mouse, confirming the spread of the latter species in the country. Small mammal diversity and abundance were not dependent on crop type but decreased in line with the intensity of agricultural practices, not being found in the most intensively cultivated farms. Unexpectedly, small mammal diversity in apple orchards exceeded the diversities found in most types of forests and was significantly higher than in crop fields.Small mammals are not only pests but also an important part of agricultural ecosystems. The common vole is a reference species for risk assessment of plant protection products in the European Union, but no data about the suitability of the species in the Baltic countries are present so far. Using the snap-trap line method, we evaluated species composition, abundance, and diversity of small mammal communities in commercial orchards and berry plantations in Lithuania, testing the predictions that (i) compared with other habitats, small mammal diversity in fruit farms is low, and (ii) the common vole is the dominant species. The diversity of small mammals was compared with control habitats and the results of investigations in other habitats. Out of ten small mammal species registered, the most dominant were common vole and striped field mouse. Small mammal diversity and abundance increased in autumn and decreased in line with the intensity of agricultural practices but were not dependent on crop type. In the most intensively cultivated fruit farms, small mammals were not found. The diversity of small mammal communities in fruit farms was significantly higher than in crop fields and exceeded the diversities found in most types of forests except those in rapid succession.

Multi-scale approach to disentangle the small mammal composition in a fragmented landscape in central Brazil

Habitat quality and its availability affect the structure of communities at a variety of different spatial and environmental scales, including habitat and landscape levels. Analyses conducted at multiple scales have demonstrated the importance of landscape patterns with regard to community structure. We used a multi-scale approach to better understand the composition of small mammal communities in central Brazil. We delimited 24 sampling units for the purpose of investigating the response of small mammal composition at the habitat, patch, and landscape scales, while evaluating quality and availability of habitat in each patch, as well as landscape configuration and landscape composition. We used a Mantel correlogram to check for spatial autocorrelation, and partial redundancy analysis to correlate the matrix of species composition with the matrix of environmental variables. Small mammal composition was spatially structured and correlated with variables at all environmental scales: vegetation structure (fallen logs, lianas, and canopy cover), habitat patch (normalized difference vegetation index [NDVI]), and landscape composition (total core area—a forest cover metric). Our findings show evidence of the limited dispersal capacity of small mammals and the importance of habitat quality at habitat and patch scales, and habitat availability at the landscape scale, for small mammal composition. This study highlights the importance of a multi-scale approach for understanding community structure in a human-altered landscape.

Temporal dynamics in animal community assembly during post-logging succession in boreal forest.

Species assemblages can result from deterministic processes, such as niche differentiation and interspecific interactions, and from stochastic processes, such as random colonisation and extinction events. Although changes in animal communities following disturbances have been widely examined, few studies have investigated the mechanisms structuring communities during ecological succession. We assessed the impact of logging on small mammal and beetle assemblages in landscapes dominated by old-growth boreal forests. Our objectives were to 1) characterize variations in communities during the first 66 years of post-harvest forest succession, 2) determine if there are non-random patterns of species co-occurrence (i.e., deterministic processes), and if there are, 3) establish whether non-random co-occurrences are best explained by habitat attributes or by interspecific interactions. We captured small mammals and beetles along a gradient of forest succession (5–66 years) and in old-growth forest, and characterized key vegetation attributes. First, we tested whether community compositions in clear-cut stands became similar to those in natural stands after 66 years. We then used null models, which were either unconstrained or constrained by habitat attributes, to address the last two objectives and distinguish effects of vegetation attributes from interspecific interactions on community assembly. We showed that beetle assemblages differed in stands 21–30 years post-harvest compared to old-growth forests. In contrast, harvesting did not influence the composition of small mammal communities. Overall, our results suggest that community assembly during forest succession is driven by both stochastic and deterministic processes, the latter being linked to interspecific interactions more strongly than to vegetation attributes.

Time averaging and late Quaternary ecological replacement in Don’s Gooseberry Pit, South Dakota, USA

AbstractLate Quaternary small mammal faunas document ecological change and biotic responses to past climates but are especially rare in some geographic regions such as the North American Great Plains. Don’s Gooseberry Pit (DGP), a cave in the southeastern Black Hills of South Dakota, USA, contains a fauna documenting small mammal community composition shifts and environmental change over the last 18,000 yr in this data-depauperate region. Although the stratigraphy of the cave appears to be primary, disparate radiocarbon dates indicate that there is mixing of the fauna throughout. A paleoenvironmental signal consistent with regional reconstructions still emerges from an analysis of the stratigraphically ordered fauna. Dated taxa from DGP record the ecological replacement of Dicrostonyx by Myodes and later Microtus in response to late Quaternary warming. Individually dated specimens of Dicrostonyx richardsoni confirm late survival of this cold-adapted taxon in the Black Hills (17,083 cal yr BP). Our results indicate that a coarse paleoecological signal is present in DGP, and that the Black Hills served as a “high-altitude” refugium for cold-adapted species following the end of the last glacial period.

The importance of considering both taxonomic and habitat guild approaches in small mammal research

AbstractStudies on the effects of habitat fragmentation on small mammals often lead to confounding results as they only consider taxonomic groups in their analysis and neglect functional diversity of the communities. Here we describe the structure and composition of small mammal communities at 22 sites, ranging from 41 to 7035 ha, in a hyper‐fragmented landscape of an Amazonia‐Cerrado ecotone. Also, in considering a taxonomic and habitat guild approach, we report the effects of habitat structures and patch spatial attributes on richness, abundance and species composition. Small mammal richness reported in southern Amazonia (N = 23 species) is greater than most previous studies in the tropics. All rare small mammals captured in this study were forest interior species. Richness of forest interior species was positively related to larger patches, as shown by the species–area relationship. However, 52% of the small mammal species were in forest fragments smaller than 50 ha, highlighting the importance of preserving both large and small forest fragments in a landscape with accelerated habitat reduction. Richness of edge‐tolerant species was not associated with the tested variables, yet edge‐tolerant species were more abundant in degraded environments. Marsupials were positively associated with vertical habitat structures, while rodents were more strongly related to a ground‐level habitat structure. The landscape studied is extremely variable and has contributed to the difficulty in detecting clear patterns, particularly when considering only one approach. Because of the complementary outputs when analysing either taxonomic groups or habitat guilds, we recommend the use of multi‐taxa studies of different guilds to assist decision makers in designing conservation strategies and appropriate management of small mammal populations.

Owl pellets: a more effective alternative to conventional trapping for broad‐scale studies of small mammal communities

Summary Small mammal community composition is almost universally estimated from conventional trapping, which is logistically difficult to scale up for landscape‐level assessments. Owl pellets may be a more effective alternative for measuring small mammal community composition over large geographic areas due to the relative ease and low cost of field collections. However, owl pellets may introduce sampling biases that differ from those associated with conventional trapping. A thorough comparison to conventional traps is required before owl pellets can be widely adopted as an alternative research tool for small mammal studies. We conducted a literature review of owl diet‐prey availability studies to: (i) compare small mammal community composition between owl pellets and trapping when the two methods were used simultaneously and (ii) assess the influence of owl genus and habitat type on community composition estimated by these two methods. We used data from 27 published studies, which allowed for 32 comparisons between owl pellets and trapping conducted simultaneously. These studies included 15 owl species from five common genera from different major habitats. Rarefied estimates showed that owls consistently sampled identical or higher species richness compared to conventional trapping. Richness estimates rarefied to the lowest sample size per study were not statistically identical (μΔrichness = 0·20 ± 0·09 SE, P = 0·30); on average, 0·95 ± 0·13 SE additional species were identified from pellets compared to trapping. Measures of species dominance and evenness estimated from both methods were statistically identical (μΔ1‐D = 0·02 ± 0·03 SE; μΔPIE = 0·004 ± 0·04 SE). Species lists, relative species composition and species rank‐order abundance were in moderate agreement between sampling methods (Jaccard = 0·62 ± 0·04 SE; Bray–Curtis = 0·53 ± 0·04 SE; Spearman rho = 0·41 ± 0·07 SE). Linear regression and AIC model selection showed that the performance of pellets versus traps did not differ based on owl genus or habitat type. Small mammal community composition estimated via pellets was better represented compared to estimates from conventional trapping. Composition metrics from the two methods were consistent and not affected by owl genera or habitat type. Thus, owls are an effective alternative for landscape‐level assessments of small mammal communities.

Defaunation affects the populations and diets of rodents in Neotropical rainforests

Most tropical rainforests have been defaunated of large-bodied mammals and the cascading effects of such extirpations have been poorly studied, particularly on other animals. We used a natural experiment in the Brazilian Atlantic rainforest to investigate the ecological responses of rodents to the functional extinction of a dominant terrestrial mammal, the white-lipped peccary (Tayassu pecari). We detected a 45% increase in the abundance and a decrease in diversity of rodents in defaunated forests. Two of these species (Akodon montensis and Oligoryzomys nigripes) are important hosts of Hantavirus, a lethal virus for humans. Stable isotope ratios (δ13C and δ15N) derived from the hair of rodents and peccaries and their food resources indicate that at least two rodent species shifted to a diet more similar to peccaries in the defaunated forest. Because most tropical rainforests are facing dramatic extirpation of large mammals, we can expect changes in the composition and structure of small mammal communities with potential consequences for human health even in non-fragmented landscapes.

Are recent changes in the terrestrial small mammal communities related to land use change? A test using pellet analyses

AbstractHuman‐induced landscape changes are expected to have strong effects on the composition and structure of terrestrial small mammal communities (Orders Rodentia and Soricomorpha). However, testing such expectations is difficult due to low detectability of these animals. We used analyses of barn owl (Tyto alba) pellets sampled in the same roosting places during 1977–1991 and again in 2011–2014 to (a) document small mammal community changes and (b) relate them to changes in land use. Forest and synanthropic small mammals increased by a 7 % between both periods, whereas open‐land species decreased by 13 %. Man‐made loss (crops and meadows) and expansion (forest and urban) of relevant habitat types were closely related to these changes. Localities with land use changes opposite to the general trend showed also an opposite trend in small mammal community change. Land use heterogeneity increased and dominance decreased between both sampling periods, and this pattern was paralleled by an increasing trend in diversity and a decreasing trend in dominance in small mammal communities. Decreasing trends of some generalist northern species with restricted ranges may have been due to climate change. Diet monitoring of barn owls are thus valuable tools for both documenting and analyzing fine‐grained small mammal responses to global change.

Wild small mammals in intensive milk cattle and swine production systems

Some rodent species are considered important pests around the world because they cause economic losses and sanitary problems. Although rodents are found in many different environments, they select habitat patches where resources are available. There is scant information regarding community composition and habitat distribution of small mammals in dairy and pig production systems. The aim of this research was to compare the composition of wild small mammal communities between intensive dairy and pig farms and to describe their distribution among habitats within the farms in northeast Buenos Aires province, Argentina. The intent is to contribute to management strategies of small mammals in these production systems. Ten pig farms and eight dairy farms were sampled seasonally during one year. Cage and Sherman live traps were set in five habitats within the farms. A total of 505 small mammals (270 in dairy farms and 235 in pig farms) were captured in 7026 cage trap-nights and 7333 Sherman trap-nights. In both production systems, the rodents captured included the dominant murines: Rattus norvegicus, R. rattus and Mus musculus, native sigmodontines: Azodon azarae, Calomys laucha and Oligoryzomys flavescens and the native caviid Cavia aperea. The opossums Didelphis albiventris and Lutreolina crassicaudata were also captured. The introduced murines used mainly human buildings, food storage sheds and animal sheds, whereas native species were more common in the vegetated environments among dwellings. A recommendation for control of pest rodent species would be to apply rodenticides only in dwellings to avoid accidental poisoning of non-target native species. Further studies on the damage produced by small mammal species and their role in the disease transmission in these production systems are necessary to identify management priorities.

Decreased small mammals species diversity and increased population abundance along a gradient of agricultural intensification

Agricultural intensification has been widespread worldwide over the last decades and has lead to a loss of semi-natural habitats. These changes are likely to have aected both the composition and diversity of small mammal communities living in agricultural landscapes. In this context, we comparedpopulationabundance(expressedasanindexofrelativeabundance), speciesrichness(S), andspeciesdiversity(expressedasShannonandPielouindexes)ofsmallmammalassemblages(i.e. sub-sets of the entire small mammal community) living in three areas in North-East Italy positioned alongagradientofagriculturalland-useintensification(measuredwiththeLandscapeConservation Index). We expected that assemblages would be less diverse and dominated by generalist species where the landscape was more intensely cultivated and where semi-natural habitats were less common. In the three areas, from a total of 4630 trap-nights, 668 individuals were captured with Sherman traps, belonging to four species (Apodemus agrarius, A. flavicollis, A. sylvaticus and Microtus arvalis). The results showed that population abundance, type of species present (but not species richness), and species diversity were aected by agricultural intensification and landscape naturalness. In particular, moving from less natural to more natural landscapes, we observed no eect on richness of species but increasing diversity due to a greater abundance of the more specialist species, such as A. agrarius and, partially, A. flavicollis, the latter only present in the most natural area. Generalist species, namelyA. sylvaticus, and those associated withdisturbed environments, such asM. arvalis, were instead more abundant in less natural landscapes. When considering population abundance, the highest overall abundance of small mammals was found in the most disturbed landscape. The results were consistent with those of research carried out in other agroecosystems of Europe and highlight the controversial eect of the anthropogenic impact on small mammal assemblages, since a decrease in species diversity may be associated with an increased overall population abundance, due to the success of few generalist species.

Developmental instability of the organism as a result of pessimization of environment under anthropogenic transformation of natural landscapes

The value of fluctuating asymmetry is considered to be an indicator of the developmental instability of the organism. The consequences of activities of the mining industry plants, which are characterized by alienation and transformation of large areas of natural landscapes, are analyzed as an anthropogenic factor. The objects of study were small mammals (northern red-backed (Clethrionomys rutilus) and gray red-backed (Clethrionomys rufocanus) voles, tundra vole (Microtus oeconomus), Laxmann's (Sorex caecutiens) and tundra (S. tundrensis) shrews) and trees (Japanese white birch (Betula platyphylla), Betula divaricate, Betula exilis, Duschekiafruticosa, and common osier (Salix viminalis)). In total, 3500 skulls and approximately 30000 leaves collected in the taiga zone of Yakutia were studied. The index offluctuating asymmetry, as well as population parameters and composition of small mammal communities, were analyzed. The data on the value of the fluctuating asymmetry in the studied species in natural habitats are given. It is shown that, in natural conditions, this parameter can rise with deterioration in living conditions, particularly at the ecological periphery of the range. Anthropogenic transformation of natural landscapes creates an "anthropogenic periphery" and causes changes similar to the adaptive responses at the northern limit of the distribution of species. It was found that, through pollution and disruption of ecosystems, the mining industry affects all levels of organization of the living matter, but the population and cenotic parameters give an unambiguous response only at macroanthropogenic transformations. Increase in the level of fluctuating asymmetry is the most sensitive indicator of anthropogenic impact and it should also be taken into account that disruptions in the developmental stability of an organism reflect the destructive processes occurring in the population and community.

Use by small mammals of a chronosequence of tropical rainforest revegetation

Context The conversion of tropical rainforest to grazing pasture results in a drastic change in small-mammal community composition. Restoring the landscape through ecological revegetation is thus an increasingly important management technique to conserve rainforest mammals. Aims This study aimed to determine the habitat ages at which species of small mammals recolonised revegetated habitats on the southern Atherton Tablelands, north-eastern Queensland, Australia. We focussed on changes in rainforest mammal abundance and diversity with increasing habitat age. Methods Small-mammal trapping and mark–recapture techniques investigated mammal diversity, abundance and community composition within remnant rainforest, three age classes of ecological revegetation and abandoned grazing pasture. Key results Small-mammal community composition differed between remnant rainforest and abandoned grazing pasture. The pasture and 3-year old revegetated sites were similar in composition, both lacking rainforest small mammals. Six- and 7-year old revegetation plantings provided suboptimal habitat for both rainforest and grassland mammals, whereas 16- and 22-year old revegetated habitats were dominated by rainforest species, with some individuals being frequently recaptured. Conclusions As revegetated habitats aged, the small-mammal community composition transitioned from a grassland-like composition to a community dominated by rainforest species. Implications Although rainforest small mammals were very occasionally captured within the 6- and 7-year old habitats, revegetated plantings were not dominated by rainforest species until the habitat was 16 years old. This highlights the importance of commencing revegetation as early as possible to minimise future population declines and maximise the conservation of rainforest mammals.

Roadside habitats: effects on diversity and composition of plant, arthropod, and small mammal communities

Road edge effects cover extensive areas and exert a wide range of ecological influences on nearby plants and animals. Most studies have focused on individual and population level effects of the road edge; less is known about how communities and their functionality are altered in proximity to roads. Here, we studied the effect of road edges on species richness, rarity, endemism, composition, and functional (trophic) classification of communities of plants, ground-dwelling arthropods (beetles, spiders, scorpions, diplopods), and small mammals. The study, conducted in a Mediterranean ecosystem in central Israel, included sampling of these taxa in 10 plots adjacent to a regional road, and in 12 nearby control plots located in a typical shrubland habitat. We found a variety of community level road edge effects on the structure, composition, and function of the studied communities. The extent of effects varied among taxa, but they were generally positive or neutral. For the species-rich taxa (plants, beetles, and spiders), distinct road edge communities characterized by higher richness and altered species composition were found. Rarity and endemism were lower, and the proportion of disturbance-associated plant species was higher at the road edge. Among the species-poor taxa, scorpions and small mammals were more abundant along road edges than in control plots, while diplopods, the only negatively affected taxon, showed decreased abundance along the road. No ecologically meaningful changes in richness or composition were detected for the species-poor taxa along the road edge. Road edges profoundly affect floral and faunal communities, with possible implications for biodiversity conservation.

Diversity and abundance of Small Mammals in Giritale Nature Reserve

The composition of small mammal communities in forest, shrub land, grassland and anthropogenic habitats of the Giritale Nature Reserve of north central Sri Lanka was studied from June 2006 to August 2007 to estimate the abundance and diversity of small mammals inhabiting this nature reserve. Live trapping using Sherman traps and Pitfall traps were adopted to catch the small mammals. A total of 71 individuals representing two orders (Insectivora and Rodentia) and three families (Soricidae, Muridae, Scuridae) was captured. Species recorded included Suncus murinus murinus Linnaeus, 1766 (Common Indian Musk Shrew), Mus cervicolor fulvidiventris Blyth, 1852 (Ceylon Field Mouse), Mus mus culuscastaneus Waterhouse, 1843 (Indian Field Mouse), Mus fernandoni Phillips, 1932 (Ceylon Spiny Mouse), Rattus blanfordi Thomas, 1881 (White Tailed Rat), Funambulus palmarum Linnaeus, 1766 (Indian Palm Squirrel) and Rattus rattus. The species Rattus rattus consisted of two subspecies Rattus attusrattus Linnaeus, 1758 (Common House Rat) and Rattus rattus rufescens Gray, 1837 (Indian House Rat). Highest and lowest abundances were recorded in the grasslands (0.08) and shrub lands(0.01), respectively. Highest diversity index was recorded in anthropogenic habitats (1.62), which included paddy fields, home gardens and buildings, while lowest diversity index was recorded in shrub lands (0.67). The number of small mammals captured was significantly different in the four habitat types (χ2 = 22.69, df = 3, p<0.05). This study, which is the first detailed examination of terrestrial small mammals in a dry zone forest of Sri Lanka, indicated that the Giritale Nature Reserve is home to six species of small mammals. Key words: Abundance, Diversity, Evenness, Nature reserve, Small mammals

Composition and abundance of small mammal communities in forest fragments and vegetation corridors in Southern Minas Gerais, Brazil

Habitat fragmentation leads to isolation and reduce habitat areas, in addition to a series of negative effects on natural populations, affecting richness, abundance and distribution of animal species. In such a context, habitat corridors serve as an alternative for connectivity in fragmented landscapes, minimizing the effects of structural isolation of different habitat areas. This study evaluated the richness, composition and abundance of small mammal communities in forest fragments and in the relevant vegetation corridors that connect these fragments, located in Southern Minas Gerais, Southeastern Brazil. Ten sites were sampled (five forest fragments and five vegetation corridors) using the capture-mark-recapture method, from April 2007-March 2008. A total sampling effort of 6 300 trapnights resulted in 656 captures of 249 individuals. Across the 10 sites sampled, 11 small mammal species were recorded. Multidimensional scaling (MDS) ordinations and ANOSIM based on the composition of small mammal communities within the corridor and fragment revealed a qualitative difference between the two environments. Regarding abundance, there was no significant difference between corridors and fragments. In comparing mean values of abundance per species in each environment, only Cerradomys subflavus showed a significant difference, being more abundant in the corridor environment. Results suggest that the presence of several small mammal species in the corridor environment, in relatively high abundances, could indicate corridors use as habitat, though they might also facilitate and/or allow the movement of individuals using different habitat patches (fragments).

Phenotypic changes and small mammal impoverishment on a Brazilian Atlantic Forest Island

Faunal impoverishment and distorted species compositions are common phenomena in oceanic islands; however, many land-bridge islands are poorly inventoried, especially in the Neotropics. We sampled a small mammal community on a land-bridge island (Anchieta Island) along the Brazilian coast. We found only one marsupial Didelphis aurita (Wied-Neuwied, 1826) and two rodent species Oligoryzomys nigripes (Olfers, 1818) and Trino- mys iheringi (Thomas, 1911) during 12 months of live trap- ping and 9195 trap-nights. The diversity of rodents and marsupials was not explained by species-area relations, indicating possible past extinctions. The abundance of D. aurita and O. nigripes was approximately three times higher, while the abundance of T. iheringi was approxi- mately four times lower than abundances reported from other Brazilian Atlantic Forest sites. The population of D. aurita exhibited many phenotypic changes; males were on average 8 % smaller and females produced 30 % less litters than those from the mainland and other land-bridge islands. The long history of forest disturbance, habitat loss, reduction in forest productivity, and the recent intro- duction of mesopredators may be the major drivers that explain the small mammal community composition on this island.