Small Mammal Species Richness Research Articles

Artificial refuges did not increase small mammal abundance after fire

AbstractThe interacting threats of invasive predators and altered fire regimes are key conservation issues for many native species globally. Artificial refuges have been proposed as a potential conservation tool to provide prey species with protection from invasive predators after fire, but we do not yet know whether they improve animal survival. To address this knowledge gap, we experimentally tested how small mammal abundance and species richness were influenced by the provision of artificial refuges after prescribed burns. We surveyed small mammals across five unburnt sites, seven burnt sites with artificial refuges, and eight burnt control sites following two prescribed fires in southeastern Australia. There were negative and neutral responses of small mammals to the burns, and relative abundance was positively correlated with structurally complex vegetation. Artificial refuges had no impact on abundance or species richness, irrespective of burn coverage. These findings suggest that this artificial refuge design may not be an effective tool for improving small mammal population persistence postfire, and as such we should not yet scale up their application. However, given the inherent context‐dependency of field experiments involving fire, which include difficult‐to‐control variables such as fire severity, predator activity, and population dynamics, we encourage researchers to undertake further experiments with artificial refuges in fire‐affected areas, including after severe wildfires when less vegetation cover remains. Such studies will help to build our understanding of their utility as a conservation tool across different ecosystems and fire types.

A new species of the endemic Tarsomys clade (Muridae, Rodentia) from eastern Mindanao Island, Philippines

Abstract Based on molecular and morphological evidence, we describe a new species of murine rodent from Mt. Kampalili in easternmost Mindanao Island, Philippines. It is the third known species of Tarsomys, a genus endemic to Mindanao. The new species differs from congeners (T. apoensis and T. echinatus) in having smaller body size, shorter tail, smaller hind feet, soft and dense pelage of darker color, smaller skull with a broader zygomatic plate, shorter incisive foramina, and longer auditory bullae. The new species belongs to the “Tarsomys clade” of tribe Rattini that has diversified principally on Mindanao where, in addition to the 3 species of Tarsomys, it is represented by 2 species of Limnomys and 1 species of Baletemys. The Tarsomys clade also includes the Rattus everetti complex which is widespread throughout the oceanic portion of the Philippines and likely consists of at least 4 species. Molecular phylogenetic analysis strongly supports a sister relationship between this new species and T. apoensis, which diverged approximately 1.0 to 1.75 Ma. The phylogenetic position, morphological distinctness, and relatively ancient persistence of this species support within-island diversification as the most substantial contributor to existing species richness of small mammals in the Philippines.

Efficiency of live trapping protocols to assess small mammal diversity in tropical rainforests of Sri Lanka

Live trapping is used extensively for small mammal studies in both temperate and tropical ecosystems. The effectiveness of such studies is dependent on several factors. This paper attempts to investigate how one of these factors, namely the trapping intensity, affects the assessment of species richness and abundance of small mammals in rainforest ecosystems in southwest Sri Lanka. Eight-day live trapping surveys were conducted in seven selected forests yielding a total of 5600 trap days with a total of 186 individuals belonging to nine species being captured. It was evident that, using 100 traps with a trap density of 140 traps per ha, over 90% of the species recorded from each of the seven forests were captured within the initial four days of live trapping after which the rate of capture of new species sharply declined. The results also show that the more common species were captured sooner than the more rare ones. Considering these trends, a four-day trapping protocol could be recommended to broadly compare small mammal communities between forests or habitat types. The number of individuals captured, on the other hand, probably attracted by the bait, increased as trapping progressed; this very likely leads to overestimation of species abundance. Since such projects in developing countries are subject to budgetary constraints, costs incurred are also addressed.

Experimentally testing animal responses to prescribed fire size and severity.

Deserts are often highly biodiverse and provide important habitats for many threatened species. Fire is a dominant disturbance in deserts, and prescribed burning is increasingly being used by conservation managers and Indigenous peoples to mitigate the damaging effects of climate change, invasive plants, and land-use change. The size, severity, and patchiness of fires can affect how animals respond to fire. However, there are almost no studies examining such burn characteristics in desert environments, which precludes the use of such information in conservation planning.Using a before-after control-impact approach with 20 sampling sites, we studied the outcomes of 10 prescribed burns of varying size (5-267ha), severity, and patchiness to identify which variables best predicted changes in small mammal and reptile species richness and abundance. Three of the 13 species showed a clear response to fire. Captures increased for 2 species (1 mammal, 1 reptile) and decreased for 1 species (a reptile) as the proportional area burned around traps increased. Two other mammal species showed weaker positive responses to fire. Total burn size and burn patchiness were not influential predictors for any species. Changes in capture rates occurred only at sites with the largest and most severe burns. No fire-related changes in capture rates were observed where fires were small and very patchy. Our results suggest that there may be thresholds of fire size or fire severity that trigger responses to fire, which has consequences for management programs underpinned by the patch mosaic burning paradigm. The prescribed burns we studied, which are typical in scale and intensity across many desert regions, facilitated the presence of some taxa and are unlikely to have widespread or persistent negative impacts on small mammal or reptile communities in this ecosystem provided that long unburned habitat harboring threatened species is protected.

Decline in small mammal species richness in coastal-central California, 1997-2013.

The richness and composition of a small mammal community inhabiting semiarid California oak woodland may be changing in response to climate change, but we know little about the causes or consequence of these changes. We applied a capture-mark-recapture model to 17 years (1997-2013) of live trapping data to estimate species-specificabundances. The big-eared woodrat was the most frequently captured species in the area, contributing 58% of total captures. All small mammal populations exhibited seasonal fluctuations, whereas those of the California mouse, brush mouse, and pinyon mouse declined during the study period. We also applied a multispecies dynamic occupancy model to our small mammal detection history data to estimate species richness, occupancy (), detection (p), local extinction (), and colonization () probabilities, and to discern factors affecting these parameters. We found that decreased from 0.369 ± 0.088 in 1997 to 0.248 ± 0.054 in 2013; was lower during the dry season (May-September) than the wet season (October-April) and was positively influenced by total seasonal rainfall (slope parameter, = 0.859 ± 0.371; 95% CI = 0.132-1.587). Mean mammalian species richness decreased from 11.943 ± 0.461 in 1997 to 7.185 ± 0.425 in 2013. With highly variable climatic patterns expected in the future, especially increased frequency and intensity of droughts,itis important to monitor small mammal communities inhabiting threatened California oak woodlands.

The positive response of small terrestrial and semi-aquatic mammals to beaver damming

Ecosystem engineers, such as the Eurasian beaver, Castor fiber, transform habitats, thereby creating favourable conditions for other species and increasing biodiversity. Multiple studies have revealed that beaver ponds are valuable habitats for invertebrates and vertebrates, including other mammals, but the impact of watercourse damming on the fauna of small terrestrial rodents and shrews has not yet been documented. We tested the hypothesis that the presence of beaver dams and consequent flooding enrich the small mammal assemblage both quantitatively and qualitatively. We live-trapped small mammals at nine beaver-modified sites on 300-metre transects alongside dammed watercourses, starting from the dam through to the pond to the sections with unmodified lotic conditions. The abundance and species richness of trapped small mammals were highest near the dams and declined with distance. Additionally, five out of 12 trapped species significantly decreased their abundance with linear distance along the shoreline from the dam and none revealed the opposite trend. Four species were more abundant on plots subjected to beaver-related inundation (especially Sorex minutus and Micromys minutus), while none were present solely on uninundated plots. Among the semi-aquatic species, two water shrews benefited from beaver activity in different ways. Neomys milleri occurred only in flooded sections, while N. fodiens preferred unmodified sections, but was the most numerous species closer to the dams, as per known patterns of competitive displacement observed in Central Europe. An important factor affecting small mammals, the herbaceous layer cover, appeared to be interdependent with damming. We provide the first unequivocal evidence that the presence of beaver dams facilitate the abundance and diversity of small mammals, presumably due to increased food abundance, availability of shelter and habitat connectivity. Beaver-created wetlands may act as potential refuges for species most susceptible to the consequences of anthropogenic climate change.

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.

Does small mammal species richness have a bimodal elevation gradient in Sikkim Himalaya?

The most reported elevation gradients in species richness are a unimodal peak and linear decline. However, the overlap of different biogeographic realms in a region can influence such gradients. We used live-capture data on small mammals (voles, rats, mice, shrews, and pikas) to describe elevation gradients in species richness in Sikkim, where Afrotropical, Indo-Malayan, and Palearctic fauna occur in the lower, middle, and higher elevations, respectively. We sampled 38 trap lines in an elevation range of 300 m to 4,200 m, which we binned into nine elevation zones. Each trap line had 50 Sherman traps run for 3–5 nights during 2003–05 and 2012–13. We had a total of 9,069 trap nights with 430 captures, including 13 species of murid rodents, five ground shrews, two voles, and one each of pika and tree shrews. The capture rate in a trap line ranged from 0 to 19.7 per 100 trap night (mean = 5.30±0.767 SEM) with a peak at 2,501–3,001 m (3.29±0.644), coinciding with temperate broad leaf and conifer forests. Species richness seemed to have a minor peak at 501–1,000 m (2.50±0.645 species per trapline) and a clear peak at 3,001–3,500 m (3.29±0.644), coinciding with tropical forests and temperate mixed conifer forests, respectively. The apparent bimodal elevation gradient is due to the overlap of western Asian and Indo-Malayan fauna in the lower elevation and of the latter and Palearctic fauna in the higher elevation. More intensive sampling is needed to test this hypothesis that the overlap of biogeographic regions can influence elevation gradient in species richness.

Diversity – volume relationships: adding structural arrangement and volume to species – area relationships across forest macrosystems

The species – area relationship (SAR) is a common pattern in which diversity increases with the area sampled, but ecosystems are three‐dimensional (3D) and diversity – volume relationships (DVRs) may exist in ecosystems that vary substantially in their vegetation volume. We tested whether forest vegetation volume, as a 3D extension of area in SARs, was a significant predictor of taxonomic (species) and structural (arrangement) diversity in five groups of organisms across the National Ecological Observatory Network (NEON). Vegetation volume and four structural arrangement metrics within the area of NEON plots were measured using NEON's discrete return lidar. Species richness was measured as the number of species within the respective NEON plot sampling area for understory plants, trees, breeding land birds, small mammals, and ground beetles. We found that volume negatively predicted understory plants and positively predicted tree and beetle species richness across the USA forest macrosystem, but not bird and small mammal species richness. Furthermore, volume was a significant predictor of several metrics that describe the internal and external heterogeneity of vegetation in forests (structural arrangement) within the ecosystem across the USA forest macrosystem. There were several significant within site‐level relationships, but not at all sites, between volume and species richness or structural arrangement in organism groups. Our study indicates that previous work that has focused on a 2D conceptualization of habitat can be expanded to 3D habitat space, but that the strength and the positive or negative direction of DVRs may vary taxonomically or geographically.

Species richness and abundance of small mammals from Nimba region, Northeastern Liberia

This study was carried out in a biodiversity hotspot within the Nimba region located in the northeastern part of Liberia. The Nimba region is known to harbor exceptional fauna diversity. However, the small mammal communities in Nimba region are poorly documented. The aim of this study was to determine the species richness and relative abundance of rodents and shrews in five sites: Bento, East Nimba, Gangra-Yuelliton, Tokadeh and Vayampah. A total of 244 individual of small mammals comprising 18 species were trapped on 4,375 trap nights. Rodent species recorded include: Arvicanthis rufinus, Dephomys defua, Grammomys buntingi, Graphiurus lorraineus, Hybomys planifrons, Hybomys trivirgatus, Hylomyscus simus, Lemniscomys striatus, Lophuromys sikapusi, Malacomys edwardsi, Mastomys erythroleucus, Mus muscoloides, Mus setulosus and Praomys rostratus. Shrew species were Crocidura eburnea, Crocidura jouvenetae, Crocidura muricauda and Crocidura obscurior. The most dominant species was Hylomyscus simus (22.95%), followed by Praomys rostratus, Crocidura muricauda and Crocidura eburnea. The highest species richness was recorded at Gangra-Yuelliton and lowest at Tokadeh. Diversity indexes were higher at East nimba (H’ = 2.01; 1-D = 0.82) and Gangra-Yuelliton (H’ = 2.00; 1-D = 0.83) and lower at Tokadeh (H’ = 1.57; 1-D = 0.75). Similarity index revealed high resemblance in species composition between Bento and Vayampah. The lowest similarity was observed between Tokadeh and Gangra-Yuelliton. This study highlighted the high biological diversity of small mammal communities in Liberia's Mount Nimba region. Thus, this zoological group should now be taken into account in the biodiversity conservation strategies of Mount Nimba

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.

Small mammals in a mountain ecosystem: the effect of topographic, micrometeorological, and biological correlates on their community structure

An increasing number of studies have investigated spatial and temporal patterns in species richness and assemblage composition in mountain ecosystems along altitudinal gradients. Small mammals have been successfully used as indicators of environmental health and as proxies of biodiversity. However, information about the composition and distribution of species assemblages in the mosaic of habitat and rocky landform types at a high altitude is still lacking for most of the mountain regions. Through the use of live traps and camera trapping, we described the small mammal community living above the treeline of the Western Dolomites (Italian Alps), investigating the species richness, abundance of individuals and community composition in relation to topographic, micrometeorological, mesohabitat, and biological correlates. A total of five species and 50 individuals were sampled, analysed, and released. At the extremes of the analysed altitudinal range (i.e. 1900 vs 2900 m a.s.l.), community composition was completely different and species richness was related to elevation, steepness, and vegetation cover. At the same time, the taxonomic distinctness of ground-dwelling arthropods (namely carabid beetles and spiders), a proxy of habitat complexity, showed higher values in areas with a greater small mammal species richness. We found a positive effect of steepness and rocky landform type “carsism” on the number of captured individuals, showing the importance of the availability of shelters and underground burrows for the sampled species. As a confirmation of the altitudinal shift for these species in relation to the ongoing climate change, we detected a negative impact of sub-surface ground temperature on small mammal abundance during the monitoring period. In conclusion, small mammals represent an excellent model for understanding the evolutionary processes of ecosystems, population dynamics under changing environmental conditions, and habitat vulnerabilities.

The relative influence of history, climate, topography and vegetation structure on local animal richness varies among taxa and spatial grains.

Understanding the spatial scales at which environmental factors drive species richness patterns is a major challenge in ecology. Due to the trade-off between spatial grain and extent, studies tend to focus on a single spatial scale, and the effects of multiple environmental variables operating across spatial scales on the pattern of local species richness have rarely been investigated. Here, we related variation in local species richness of ground beetles, landbirds and small mammals to variation in vegetation structure and topography, regional climate, biome diversity and glaciation history for 27 sites across the USA at two different spatial grains. We studied the relative influence of broad-scale (landscape) environmental conditions using variables estimated at the site level (climate, productivity, biome diversity and glacial era ice cover) and fine-scale (local) environmental conditions using variables estimated at the plot level (topography and vegetation structure) to explain local species richness. We also examined whether plot-level factors scale up to drive continental scale richness patterns. We used Bayesian hierarchical models and quantified the amount of variance in observed richness that was explained by environmental factors at different spatial scales. For all three animal groups, our models explained much of the variation in local species richness (85%-89%), but site-level variables explained a greater proportion of richness variance than plot-level variables. Temperature was the most important site-level predictor for explaining variance in landbirds and ground beetles richness. Some aspects of vegetation structure were the main plot-level predictors of landbird richness. Environmental predictors generally had poor explanatory power for small mammal richness, while glacial era ice cover was the most important site-level predictor. Relationships between plot-level factors and richness varied greatly among geographical regions and spatial grains, and most relationships did not hold when predictors were scaled up to the continental scale. Our results suggest that the factors that determine richness may be highly dependent on spatial grain, geography, and animal group. We demonstrate that instead of artificially manipulating the resolution to study multiscale effects, a hierarchical approach that uses fine grain data at broad extents could help solve the issue of scale selection in environment-richness studies.

Fire exclusion and fire return interval affect small mammal populations in longleaf pine forests

Longleaf pine (Pinus palustris) forests are among the most fire-dependent forest types in the world and once dominated much of the southeastern United States. Loss and fragmentation of longleaf pine shrank its distribution to approximately 4% of its historic range; as a result, longleaf pine forests currently receive much conservation and restoration emphasis. In all cases, this emphasis includes prescribed fire. Prescribed fires promote herbaceous understories which maintains habitat for some small mammals, but fires can also result in temporary declines of small mammal populations. Therefore, short return intervals may not allow small mammal populations to recover between fires, and long return intervals may result in declining habitat quality and reduced small mammal abundance. During the first phase of our research, we studied the long-term influence of prescribed fire on small mammals. We annually estimated small mammal abundance and species richness during 2001 – 2014 in eight longleaf pine-dominated plots in southwestern Georgia, USA. Plots were either biennially burned (reference) or had fire excluded during the study. Small mammal species richness was similar in fire-excluded and reference sites. Overall small mammal abundance was greatest in reference plots. Five species were captured with sufficient frequency to justify species-specific analyses. Of these, three (hispid cotton rats, Sigmodon hispidus; oldfield mice, Peromyscus polionotis; and house mice, Mus musculus) were more abundant in reference plots. For the second phase of our research, we reintroduced fire in half of the fire excluded plots (burned during 2015, 2016, and 2017) and began sampling small mammals in three additional plots that were burned annually since 2003. We collected data during 2017 and 2018 for this phase of the research to evaluate small mammal response to four prescribed-fire return intervals (annual growing season burns since 2003, biennial burns since 2001 (reference), fire excluded since 2001, and fire excluded since 2001 and then burned during 2015, 2016, and 2017). Small mammal species richness was not affected by burn interval. Cotton rat abundance was greater in reference plots than in other treatments, whereas cotton mice (Peromyscus gossypinus) and oldfield mice were most abundant in the annually burned treatment. Three prescribed fires occurred in fire reintroduced plots prior to sampling, but these fires were insufficient to restore small mammal abundance to that of annually or biennially burned plots. Our work provides further evidence that fire is important for maintaining habitat for some small mammals and that time between fires has a species-specific effect on small mammal abundances. Thus, manipulating fire return interval is a promising tool for managing relative abundance of small mammals and likely other wildlife.

Invasive rat drives complete collapse of native small mammal communities in insular forest fragments

As tropical forests are becoming increasingly fragmented, understanding the magnitude and time frame of biodiversity declines is vital for 21st century sustainability goals. Over three decades, we monitored post-isolation changes in small mammal species richness and abundance within a forest landscape fragmented by the construction of a dam in Thailand.1,2 We observed the near-complete collapse of species richness within 33 years, with no evidence of a recolonization effect across repeatedly sampled islands. Our results further revealed a decline in species richness as island size decreased and isolation time increased, accelerated by the increasing dominance of the ubiquitous Malayan field rat, Rattus tiomanicus. This species was already hyper-abundant on smaller islands in the initial surveys (1992-1994, 66% of individuals) but became monodominant on all islands, regardless of island size, by the most recent survey (2020, 97%). Our results suggest that insular forest fragments are highly susceptible to rapid species loss, particularly due to the competitive nature of Rattus accelerating the rate at which extinction debts are paid. To mitigate these impacts, reducing the extent of habitat degradation, as triggered by fragmentation and exacerbated by isolation time, can help to sustain native biodiversity while averting Rattus hyper-abundance.

Relationships between livestock grazing intensity and mammal predator-prey: A study case in Copo National Park in the dry Chaco forests

Extensive livestock ranching is one of the main drivers of habitat degradation in terrestrial communities in the dry Chaco forest (Argentina). Grazing intensity could differentially affect native mammals and their interactions, which could impact both, native mammal communities and livestock production systems. Here, we determined how the activity index of grey foxes Lycalopex gymnocercus and capture abundance and richness of small mammals vary along a grazing intensity gradient in a particular region of the dry Chaco forest (Copo National Park, Argentina). Track plots were used to estimate the activity index of foxes and cattle, and Sherman traps for small mammals. Fresh scats were collected to analyse the diet of foxes and to assess possible changes in predator-prey dynamics. Fruit availability and shrub density were measured in 6 plots of 2 m × 50 m. We used generalized linear mixed models, Spearman’s nonparametric rank correlation, Chi-squared test, and Spearman’s partial correlation coefficient to analyse the potential effects of grazing intensity. We found that the activity index of foxes increased (0.06 ± 0.018) while small mammal abundance (-0.08 ± 0.024) and species richness decreased (rs = -0.94) with increasing grazing intensity. However, the proportion of scats with mammalian remains decreased with increasing grazing intensity. Also, we did not find a strong partial correlation between foxes and small mammals when we controlled for grazing intensity. This suggests that the abundance and diversity of small mammals in the study area are determined more by grazing intensity than by predator-prey interactions. Grazing intensity could negatively affect small mammals, but not through changes in fruit availability or shrub density, but possibly by affecting grass cover. Consequently, foxes’ activity could increase to meet caloric intake requirements. Our results suggest that specific cattle management recommendations depend on the wildlife species that serves as a conservation target. We recommend testing whether reducing cattle load can make this productive activity compatible with wildlife conservation in dry Chaco forests.

Diversity and Diet Differences of Small Mammals in Commensal Habitats

The stability of diversity of syntopic (inhabiting the same habitat in the same time) small mammals in commensal habitats, such as farmsteads and kitchen gardens, and, as a proxy of their diet, their isotopic niches, was investigated in Lithuania in 2019–2020. We tested whether the separation of species corresponds to the trophic guilds, whether their diets are related to possibilities of getting additional food from humans, and whether their diets are subject to seasonal trends. We analyzed diversity, dominance and distribution of hair δ13C and δ15N values. Diversity and dominance was not stable and differed according to human influence. The highest small mammal species richness occurred in commensal habitats that provided additional food. The degree of separation of species was higher in homestead habitats than in kitchen gardens, where a 1.27% to 35.97% overlap of isotopic niches was observed between pairs of species. Temporal changes in δ13C and δ15N values in the hair of the mammals were not equally expressed in different species. The isotopic overlap may depend on dietary plasticity, minimizing interspecific competition and allowing co-existence of syntopic species. Thus, small mammal trophic ecology is likely related to intensity of agricultural activities in the limited space of commensal habitats.

Small mammals in the human-dominated landscape in the northern Western Ghats of India

The Western Ghats biodiversity hotspot is under huge anthropogenic pressure, with unique flora and fauna facing severe threats from habitat fragmentation, loss, and degradation. The northern Western Ghats has been poorly studied for its small mammal fauna, hence we examined small mammals near Pune from 2014 to 2017. Live trapping was carried out in irrigated and rainfed agriculture fields, forests, and grasslands at low, mid, and high elevations. A total of 538 individuals were trapped, representing 17 species of rodents and one shrew. Most abundantly captured species were Millardia kondana (23%), Mus saxicola (19%), Suncus murinus (17%), and Mus booduga (13%). Species richness and abundance of small mammals varied across the habitats. High elevation grasslands were species-rich relative to low elevation grasslands and forests. Our observations indicate that human disturbances play a role in determining the richness and abundance of small mammals in the area, where populations are under threat from urbanization, tourism, agriculture, grazing, and fire. Habitat and species specific conservation measures need to be taken, coupled with in-depth species–habitat relationship studies, for the conservation of small mammal diversity of the northern Western Ghats.

Small mammals from the lasting fragments of Araucaria Forest in southern Brazil: a study about richness and diversity

ABSTRACT Rodents and marsupials together, form the most rich group of mammals in Brazil, they are distributed in all biomes, including Atlantic Forest, and can be used to analyze environmental quality. The Araucaria Forest is a threatened formation of the Atlantic forest with few areas remaining intact and a huge lack of knowledge about the potential of its secondary forest fragments to act as habitat refuges to native fauna. This study evaluated the species richness and diversity of non-volant small mammals among five vegetation types within a protected area in an Araucaria Forest area from southern Brazil. The sampling was made in six bimonthly campaigns during a year, by pitfall and live traps. This effort resulted in 875 captures of 625 individuals from 16 species. The most common species in Pine Plantation was Oligoryzomys nigripes, in Natural Regeneration forest was Thaptomys nigrita and Akodon montensis was most often captured in the other vegetation. Although differences in species composition were found among the different vegetation types, there was no significant difference in species richness. Nevertheless, true diversity values were significantly lower in the Pine Plantation. The results demonstrated that the substitution of native for exotic vegetation generated a negative impact on the group diversity. More studies, in other Araucaria Forest areas are necessary to allow better understanding of the processes driving this loss of diversity in this biome threatened by antropic action.

Management Intensity and Forest Successional Stages as Significant Determinants of Small Mammal Communities in a Lowland Floodplain Forest

The conversion of forests from complex natural ecosystems to simplified commercial woodlands is one of the major causes of biodiversity loss. To maintain biodiversity, we need to understand how current management practices influence forest ecosystems. We studied the effects of forest successional stage and management intensity on the abundance, species richness, and assemblage composition of small mammals. Our results show that management intensity significantly contributes to reducing the number of species after clearcutting. We revealed that intensively managed clearings can make the dispersal or foraging activity of small mammals difficult and hence negatively influence their abundance and species richness. The significantly higher species richness of small mammal species was recorded within more extensively rather than intensively managed clearings. In contrast, we did not observe significant changes in species richness and abundance after intensive management in old-growth forests. Species Clethrionomys glareolus and Apodemus flavicollis reached the greatest abundance in old-growth forest patches. On the other hand, Microtus arvalis and Microtus subterraneus were species mainly associated with the successionally youngest forest stands. Our analysis suggests that intensive management interventions (i.e., vegetation destruction by pesticides and wood debris removal by soil milling) in clearings produce unhostile environments for majority of the small mammal species.