Mammal Community Composition Research Articles

Assessment of Changes in the Composition and Distribution of Large and Medium-Sized Mammals in Xishuangbanna, Southwest China.

Given the vulnerability of large and medium-sized mammal communities to climate change and human disturbances, understanding the spatial-temporal dynamics of these communities is essential for effective conservation planning. However, in many biodiversity hotspots, precise biological community assessments are insufficient. From 2012 to 2022, we deployed 784 camera traps in eight nature reserves (including sub-reserves) and one State Forest Farm (SFF, less strictly protected than a reserve) to study the composition and distribution of large and medium-sized mammals in tropical Xishuangbanna. The findings revealed the following: (1) Forty-three species, encompassing six orders, 17 families, and 37 genera, were documented. Among the species in historical data, nine species were not detected in this survey. (2) Smaller and more fragmented reserves lacked larger body-sized predators and herbivores, and most common species showed lower relative population abundance. Conversely, the SFF exhibited high mammal diversity. (3) The community composition of large and medium-sized mammals varied significantly across the nine sites, particularly among threatened species. Our findings highlight the uneven distribution of these mammal communities in Xishuangbanna, with rare and large-sized species facing increased vulnerability to rapid environmental changes. Moreover, the findings demonstrate the importance of considering species specificity and uniqueness in conservation planning for maintaining regional-scale biodiversity.

Variation in species-specific responses to habitat fragmentation and land cover structure in urban small mammal communities

Abstract Urbanization is a key driver of habitat loss and fragmentation worldwide, yet many urban ecosystems contain vegetated habitat patches that support diverse wildlife communities. Managing urban systems to support robust wildlife communities requires us to understand the mechanisms that drive the response of species to the urban environment. Small mammals are key components of terrestrial ecosystems (e.g., seed predators, prey) and likely also carry out these roles in urban ecosystems; however, the effects of urbanization on small mammal communities are understudied. To identify how species-specific responses to urban environments shape community composition, we quantified both overall community and species-specific changes in small mammal abundance across an urbanization gradient in a Midwestern US metropolitan area. We combined small mammal trapping and land cover data to generate a hierarchical community abundance model. Species diversity increased with increasing proportional cover of human-modified land cover (i.e., impervious surfaces and turfgrass). This finding is driven by high species diversity on sites bordering streams in mowed parks and low diversity on sites with high tree canopy closure. Additionally, modeling results indicated that species responded differently to landscape attributes, leading to variation in small mammal community composition across the urbanization gradient: prairie-associated species tended to be more abundant in tall vegetation bordering mowed parks while habitat generalists tended to be more abundant on sites with greater canopy closure and shrub cover. Our results suggest that studies that focus on community-level responses (e.g., species richness) to urbanization may miss important species-specific responses. It may be particularly important to assess both species-specific and community-level responses in cities at ecotones (e.g., between forest and grassland) where species with different habitat requirements may replace one another in different types of green spaces, thereby changing community composition without affecting species diversity or richness. Our findings also indicate that vegetated urban patches, especially patches with tall vegetation cover and low canopy cover, are important habitat for prairie-associated small mammal communities, providing conservation options in heavily altered landscapes.

The last 20,000 years of climate change in the Iberian Peninsula characterized by the small-mammal assemblages

Climate and environments have undergone significant changes throughout the Earth's history, which are reflected in the faunal record. In that sense, small mammals provide valuable palaeoecological insights due to their close relationship with their associated environments. Our research investigates the dynamics of small mammal communities in the Iberian Peninsula from the Late Pleistocene to the Holocene, comparing regional environmental variations as well as anthropogenic impacts. Our review of the small mammal assemblages from 26 archaeological sites across the Iberian Peninsula revealed a differential response of the small mammal communities between the northern and southern areas. The colder climatic conditions which characterized the Late Pleistocene favoured the presence of mid-European species (e.g., Alexandromys (Oecomicrotus) oeconomus, Chionomys (Chionomys) nivalis) in northern regions until the Mid Holocene, while other taxa today restricted to northern Iberia (e.g., Arvicola amphibius, Microtus gr. (Euarvicola) arvalis, Sorex araneus-coronatus) reached southern regions during the Last Glacial Maximum but disappeared at the beginning of the Holocene period. Palaeoenvironmental reconstructions indicate predominantly open landscapes and colder climates in the Late Pleistocene, with increased forest cover during the Early-Mid Holocene in northern areas. In contrast, the southern regions exhibited more stable environments compared to the northern ones. Our results underscore how the great environmental diversity and interactions between natural and anthropogenic factors affected the composition of Iberian small mammal communities during the last 20,000 years. Most specifically, during the Late Holocene, biogeographical patterns of the small mammals are mostly affected by anthropic activities, with changes in the distribution of some species (Microtus (Iberomys) cabrerae), and the entrance of new ones (synanthropic species).

A case study on the impact of coppicing on small mammal diversity: First evidence from the high Agri Valley in the Basilicata Region, Italy

Forestry seems to have a significant impact on the diversity and composition of forest small mammal communities. Coppicing is one of the most widely adopted silvicultural systems in Europe and its effect on the entire small mammals community remains unclear. Thus, our study aimed to preliminary assess the stand-level effect of different coppice woodland elements on community richness, focusing on forest small mammal species. Furthermore, a second aim was to assess the effect of these woodland stand elements on different small mammal taxonomic groups to evaluate possible differential responses within the community. We identified three different coppice age classes, and selected a total of 15 coppice-with-standards forest stands. Additionally, we collected data about understory shrub structure and composition. Fur samples were collected using the hair tube sampling method. We found a significant effect of the coppice age on the number of species detected in communities. Furthermore, we found a differential response between glirid and murid families, with glirid being positively affected by a higher shrub abundance, which is instead severely reduced by coppicing.

Habitat and Body Condition of Small Mammals in a Country at Mid-Latitude

The relationship between the body condition of different small mammal species and the habitat they occupy is poorly analyzed. We analyzed the body condition index, BCI, of 18 small mammal species trapped in forest, shrub, wetland, meadow, riparian, mixed and fragmented, disturbed, agricultural, and commensal habitats of Lithuania during the span of 1980–2023. The composition of small mammal communities was habitat-dependent, being richest in meadows, with eighteen species, and poorest in riparian habitats, with nine species. A significant variation in the BCI with respect to habitat was observed in eight small mammal species (Sorex araneus, S. minutus, Apodemus agrarius, A. flavicollis, Clethrionomys glareolus, Alexandromys oeconomus, Microtus agrestis, and M. arvalis). The highest average BCI for most of these species was found in disturbed habitats, with S. minutus and M. arvalis showing the highest BCI in agricultural habitats. The lowest average BCI for most species was found in mixed habitats, while C. glareolus and M. arvalis exhibited the lowest BCI in shrub habitats. In general, species dominating certain habitats did not have the highest BCI. This is the first multi-species, multi-habitat study of body condition in small mammals at mid-latitudes.

Comparison of soil eDNA to camera traps for assessing mammal and bird community composition and site use.

Species detections often vary depending on the survey methods employed. Some species may go undetected when using only one approach in community-level inventory and monitoring programs, which has management and conservation implications. We conducted a comparative study of terrestrial mammal and bird detections in the spring and summer of 2021 by placing camera traps at 30 locations across a large military installation in northern Michigan, USA and testing replicate soil samples from these sites for environmental DNA (eDNA) using an established vertebrate metabarcoding assay. We detected a total of 48 taxa from both survey methods: 26 mammalian taxa (excluding humans, 24 to species and two to genus) and 22 avian taxa (21 to species and one to genus). We detected a relatively even distribution of mammalian taxa on cameras (17) and via eDNA analysis (15), with seven taxa detected from both methods. Most medium-to-large carnivores were detected only on cameras, whereas semi-fossorial small mammals were detected only via eDNA analysis. We detected higher bird diversity with camera traps (18 taxa) compared to eDNA analysis (eight taxa; four taxa were detected with both methods), but cameras alone were most effective at detecting smaller birds that frequently occupy arboreal environments. We also used Bayesian spatial occupancy models for two widely distributed game species (white-tailed deer, Odocoileus virginianus, and ruffed grouse, Bonasa umbellus) that were moderately detected with both survey methods and found species-specific site use (occupancy) estimates were similar between cameras and eDNA analysis. Concordant with similar studies, our findings suggest that a combination of camera trap and eDNA surveys could be most useful for assessing the composition of terrestrial mammal communities. Camera traps may be most efficient for assessing bird diversity but can be complemented with eDNA analysis, particularly for species that spend considerable time on the ground.

Disentangling the Effects of Climate and Land Uses on Small Mammals in Agroecosystems of NE Spain

We analyzed the two main drivers (climate and land uses) shaping the composition of small mammal communities at 16 localities situated in the confluence of the Mediterranean and Eurosiberian regions (Barcelona, Spain). The study area represents a land use and land cover gradient showing urbanization and crop intensification in the lowlands and forest encroachment in mountain areas. We identified 2458 small mammal individuals of 12 different species from barn owl (Tyto alba) pellets. Three open-land species (Microtus duodecimcostatus, Crocidura russula, and Mus spretus) and one forest/generalist species (Apodemus sylvaticus) were dominant in the diet, accounting for 93% of prey. In order to disentangle the effects of both main drivers on the small mammal community, we used partial constrained ordination techniques, which allowed us to determine the pure effects (and shared effects) of the environmental factors. Land use predictors explained 33.4% of the variance (mostly crops), followed by 23.4% of the variance explained by the geo-climatic variables (mostly rainfall), and an additional 24.8% of the variance was shared by both groups of predictors, totaling 81.6% of environmental variance. The remaining 18.4% of variance was unexplained by environmental matrices. This pattern was consistent with expected associations of species and biotic influences at small spatial scales and highlighted that the number of species increased from the crops in the lowlands towards the highlands covered by deciduous and coniferous forests.

Frequent prescribed burns reduce mammalian species richness and occurrence in longleaf pine sandhills

Prescribed fire is a critical forest management tool, the frequency and size of which can alter the composition of wildlife communities. In the longleaf pine ecosystem of the southeastern United States, frequent prescribed fire (1–3 year fire interval) is used to replicate natural processes that prevent woody encroachment and transition to alternate states. However, we have little understanding of how different scales and frequencies of fire influence medium and large mammals. To address this knowledge gap, we assessed the homogenizing influence of prescribed fire on mammal community composition at different fire frequencies and scales. We set 110 camera trap grids containing 990 individual camera points across conservation lands in north Florida and the Florida panhandle. We used a Bayesian multi-species occupancy modeling approach to assess the relationship between fire frequency and the occurrence of 11 mammal species across three spatial scales (0.2 ha, 12.57 ha, and 176.71 ha). Species richness was negatively associated with increased burn frequency at all scales and community occurrence was negatively associated with increased burn frequency at the two largest scales. Non-native nine-banded armadillos were negatively associated with increased burn frequency at all scales and non-native feral hogs were negatively associated with increased burn frequency at the two largest scales. Raccoons and opossums, both known nest predators, were negatively associated with increased burn frequency at the two largest scales. Our results indicate that prescribed fire applied at 1–3 year intervals could be used to reduce the occurrence of most non-native mammals and several prolific nest predators in longleaf pine sandhills, particularly at larger scales. However, these perceived benefits must be weighed against the concurrent loss of the ecosystem services and functions native generalist species provide.

Small mammal community composition impacts bank vole (Clethrionomys glareolus) population dynamics and associated seroprevalence of Puumala orthohantavirus.

Rodents are important reservoirs for zoonotic pathogens that cause diseases in humans. Biodiversity is hypothesized to be closely related to pathogen prevalence through multiple direct and indirect pathways. For example, the presence of non-host species can reduce contact rates of the main reservoir host and thus reduce the risk of transmission ("dilution effect"). In addition, an overlap in ecological niches between two species could lead to increased interspecific competition, potentially limiting host densities and reducing density-dependent pathogen transmission processes. In this study, we investigated the relative impact of population-level regulation of direct and indirect drivers of the prevalence of Puumala orthohantavirus (PUUV) in bank voles (Clethrionomys glareolus) during years with high abundance. We compiled data on small mammal community composition from four regions in Germany between 2010 and 2013. Structural equation modeling revealed a strong seasonality in PUUV control mechanisms in bank voles. The abundance of shrews tended to have a negative relationship with host abundance, and host abundance positively influenced PUUV seroprevalence, while at the same time increasing the abundance of competing non-hosts like the wood mouse (Apodemus sylvaticus) and the yellow-necked field mouse (Apodemus flavicollis) were associated with reduced PUUV seroprevalence in the host. These results indicate that for PUUV in bank voles, dilution is associated with increased interspecific competition. Anthropogenic pressures leading to the decline of Apodemus spp. in a specific habitat could lead to the amplification of mechanisms promoting PUUV transmission within the host populations.

Puumala orthohantavirus circulation in its wild reservoir, the bank vole, during the 2021 outbreak of hemorrhagic fever with renal syndrome in Jura, France

ObjectiveA large and unprecedented outbreak of an attenuated form of hemorrhagic fever with renal syndrome called nephropathia epidemica (NE) and caused by Puumala virus (PUUV) occurred in 2021 in the southern Jura Mountains (France) leading to numerous hospitalizations. The aim of this study was to investigate the circulation of PUUV in its animal reservoir at the time of this outbreak. MethodsWe conjointly surveyed bank vole relative abundance, small mammal community composition, and PUUV circulation in bank voles (seroprevalence and genetic diversity) in the Jura NE epidemic area, between 2020 and 2022. ResultsTrapping results showed a higher relative abundance of bank voles in 2021 compared to 2020 and 2022. Extremely high levels of PUUV seroprevalence in bank voles were found at the time of the human NE epidemic with seropositive animals trapped in almost all trap lines as of spring 2021. Genetic analyses of PUUV (S segment) gathered in 2021 at two sampling sites revealed a strong clustering of these strains within the “Jura” clade. No significant genetic variation was detected compared to what was already known to be circulating in the Jura region. ConclusionThese results underline a need for enhanced monitoring of PUUV circulation in host reservoir populations in NE endemic areas. This would enable the relevant actors to better inform and sensitize the public on this zoonotic risk, and to implement prevention strategies in collaboration with physicians.

Bioclimatic inference based on mammal community using machine learning regression models: perspectives for paleoecological studies

Climate has played a significant role in shaping the distribution of mammal species across the world. Mammal community composition can therefore be used for inferring modern and past climatic conditions. Here, we develop a novel approach for bioclimatic inference using machine learning (ML) algorithms, which allows for accurate prediction of a set of climate variables based on the composition of the faunal community. The automated dataset construction process aggregates bioclimatic variables with modern species distribution maps, and includes multiple taxonomic ranks as explanatory variables for the predictions. This yields a large dataset that can be used to produce highly accurate predictions. Various ML algorithms that perform regression have been examined. To account for spatial dependence in our data, we employed a geographical block validation approach for model validation and selection. The random forest (RF) outperformed the other evaluated algorithms. Ultimately, we used unseen modern mammal surveys to assess the high predictive performances and extrapolation abilities achieved by our trained models. This contribution introduces a framework and methodology to construct models for developing models based on neo-ecological data, which could be utilized for paleoclimate applications in the future. The study aimed to satisfy specific criteria for interpreting both modern and paleo faunal assemblages, including the ability to generate reliable climate predictions from faunal lists with varying taxonomic resolutions, without the need for published wildlife inventory data from the study area. This method demonstrates the versatility of ML techniques in climate modeling and highlights their promising potential for applications in the fields of archaeology and paleontology.

Diversity profiles of medium and large-size mammals in an Atlantic Forest remnant: seasonal and spatial patterns

ABSTRACT Mammal populations are declining due to habitat fragmentation and loss, but protected areas can maintain these populations at viable numbers and reduce their risk of extinction. This study assessed the mammal community composition, diversity profiles, seasonal variation, and habitat use in a protected area in the Brazilian Atlantic Forest. With an effort of 5,023 camera trap days, we registered 1,889 independent records of 20 species, with an additional 13 species recorded through direct observation. There was no difference in the seasonal diversity profiles of mammal communities. The diversity in submontane areas was consistently larger than in lowland ones, but the number of records was higher in lowland areas. The diversity profiles decrease when more weight is given to the common species. The reserve is the protected area with the third highest mammal richness in the state of Rio de Janeiro and harbors 11 threatened mammals. This study shows the importance of small protected areas for the conservation of mammalian diversity in a fragmented anthropogenic landscape.

Continuous forest at higher elevation plays a key role in maintaining bird and mammal diversity across an Andean coffee‐growing landscape

AbstractShade coffee is among the most widespread and economically important crops in montane tropical regions and is considered more hospitable to wildlife than non‐shaded crops. Questions remain regarding the value of shade coffee as habitat for wildlife, however, given the historical research focus on small‐bodied and canopy species. Simultaneously, climate‐driven upslope migration of coffee crops represents an emerging threat to well‐conserved tropical montane forest at higher elevations. This study examined ground‐dwelling birds and medium‐large mammals in a shade coffee landscape of the Western Andes of Colombia. We asked the following questions: (1) How do bird and mammal occupancy, richness, and community composition change from continuous forest at higher elevations to middle‐elevation forest fragments and shade coffee? (2) Do birds and mammals differ in their response to shade coffee? (3) Do high‐elevation forests contribute to maintaining biodiversity in mid‐elevation shade coffee? We sampled birds and mammals with camera traps in middle‐elevation shade coffee plantations and forest fragments and in continuous forest further upslope. We then used a multi‐species occupancy model to correct for imperfect detection and to estimate occupancy, richness, and community composition. Shade coffee lacked ~50% of the bird and mammal species found in continuous forest, primarily large‐bodied and insectivorous birds and forest‐specialist and large‐bodied mammals. Forest fragment richness was closer to shade coffee than to continuous forest, but species composition significantly differed between coffee and both forest types. Birds in coffee plantations were generally a unique subset of disturbance‐adapted specialists, whereas mammals in coffee were mostly generalists. Distance from continuous forest was the most important landscape‐level predictor of occupancy for both taxa, suggesting that this forest plays a key role in maintaining biodiversity across the coffee landscape. Biodiversity conservation in shade coffee landscapes, therefore, will be ineffective unless linked to landscape‐level initiatives that conserve higher elevation tropical montane forest.

Effects of a large wildfire on the community composition of medium and large mammals in a neotropical savannah

Background The Cerrado is a neotropical savannah with high mammalian diversity where wildfires are rather common and highly relevant to its ecological patterns and processes. The effects of fire on Cerrado mammals, however, are poorly understood. Aims We investigated the effects of an unplanned large wildfire (burned area ~66 000 ha) on medium and large mammals in a Cerrado area in Brazil, focusing on fire-driven changes in community composition up to 3 years after fire. Methods We evaluated burned and unburned sites before and after the wildfire, using 54 camera traps between 2017 and 2020. Total trap effort was 6334 days (unburned areas) and 7670 days (burned areas). Key results We recorded 25 species in burned and 19 in unburned areas. Fire markedly affected the community up to 3 years after burning. A canonical correspondence analysis indicated that herbivores (tapirs and pampas deer) were common in the burned areas, with an increase in the relative abundance of carnivores the second year after fire. Conclusions Community-level responses were complex, with guild-dependent changes and effects still detected 3 years after fire. Implications Management strategies that include patch mosaic burns (with areas unburned and burned 1 and 2 years earlier) could contribute to maintenance of local mammal diversity.

Small mammal taphonomy and palaeoecological Holocene interpretations in the Andean piedmont (southern Mendoza province, Argentina)

ABSTRACT Salamanca cave (southern Mendoza province) is in the Andean piedmont, a transitional area in which small mammal communities may have been affected by climatic pulses. The site yields three archaeological components covering from the early to the late-Holocene with a mid-Holocene occupational and sedimentological hiatus. Taphonomic analyses of the small mammal assemblages indicate that barn owls (Tyto furcata) were the main accumulation agent, ensuring accurate palaeoecological inferences. Taxonomic composition of the site shows the dominance of Eligmodontia sp. followed by Thylamys pallidior, Phyllotis cf. P. vaccarum-pehuenche and Ctenomys sp., all of them indicative of shrubland and bare ground habitats. Palaeoclimatic inferences indicate a trend to warmer temperatures from the lower to the upper component with a slight increase in humidity in the middle component. This humid pulse is also supported by post-depositional taphonomic processes. The taxonomic structure and abundance of small mammals do not show deep changes amongst the three archaeological components, following the general trend observed in other archaeological sites from the Pampean region, southern Mendoza province and the arid and semi-arid zones of north Patagonia, in which changes in the taxonomic composition of small mammal communities are almost absent since Pleistocene–Holocene transition to late Holocene.

Long-Term Changes in Abundance and Composition of Forest-Floor Small Mammal Communities in a Landscape with Cumulative Clearcutting

Responses of forest-floor small mammals to clearcutting are species-specific with generalists occupying a range of habitats, and specialists persisting on clearcuts for variable periods. We investigated the responses in abundance and species composition of small mammal communities to cumulative clearcutting of coniferous forests on a landscape that had four independent clearcutting events (Periods 1 to 4) over a 42-year interval from 1979 to 2020 in south-central British Columbia, Canada. We ask if the small mammal communities have changed significantly over these decades owing to removal of old-growth forest by clearcut harvesting. Hypotheses (H) predicted that the small mammal community would (H1) increase in abundance, species richness, and diversity on new clearcuts owing to the availability of early seral post-harvest habitats from cumulative clearcutting; and (H2) have higher mean abundance, species richness, and species diversity in clearcut than uncut forest sites, owing to availability of vegetative food and cover. A third hypothesis (H3) predicted that abundance of (i) early seral vegetation (herbs and shrubs) and (ii) small mammal populations, will be greater in ungrazed clearcut sites than in those grazed by cattle (Bos taurus). Mean total numbers of small mammals on new clearcuts declined in Periods 3 and 4, and hence did not support the abundance part of H1. Much of this decline was owing to low numbers of the long-tailed vole (Microtus longicaudus) and meadow vole (M. pennsylvanicus). Two generalist species: the deer mouse (Peromyscus maniculatus) and northwestern chipmunk (Neotamias amoenus), contributed to high mean species richness and diversity in Periods 2 and 3 before these metrics declined in Period 4, and hence partly supported H1. The similarity in mean total numbers of small mammals in Periods 2 to 4 did not support the abundance prediction of H2 that total numbers would be higher in clearcut than uncut forest sites. Higher mean species richness (Periods 2 and 3) and diversity (Period 3) measurements on clearcut than forest sites, particularly in the early post-harvest years, did support these parts of H2. The vegetation part (i) of H3 was not supported for herbaceous plants but it was for shrubs. The small mammal part (ii) of H3 that populations would be higher in ungrazed than grazed clearcut sites was supported for abundance but not for species richness or diversity. The decline and near disappearance of both species of Microtus was possibly related to the reduction in plant community abundance and structure from grazing (at least for shrubs) and potentially from drought effects associated with climate change. Loss of microtines from these early seral ecosystems may have profound negative effects on various ecological functions and predator communities.

Environmental DNA as a management tool for tracking artificial waterhole use in savanna ecosystems

Game parks are the last preserve of many large mammals, and in savanna ecosystems, management of surface waters poses a conservation challenge. In arid and semi-arid regions, water can be a scarce resource during dry seasons and drought. Artificial waterholes are common in parks and reserves across Africa, but can alter mammal community composition by favoring drought intolerant species, with consequences for disease dynamics, and population viability of drought-tolerant species. Analysis of waterborne environmental DNA (eDNA) is increasingly used to inform conservation of rare and invasive species, and conduct large-scale biodiversity assessments. To explore the reliability of eDNA as an indicator of mammal waterhole use in savannas, we compare eDNA metabarcoding and camera traps for documenting artificial waterhole use in the Kruger National Park, South Africa, a global hotspot for mammal diversity. We show that eDNA metabarcoding can recover the majority of mammal species detected by camera traps, including a number of endangered species, but DNA signatures of mammal visitation are temporally limited, with best performance when tracking water-dependent large bodied mammals visiting within two days of sampling. Our results highlight limitation of eDNA based monitoring in these systems, including the lack of long-term eDNA persistence in small and highly utilized waterholes, and variability in detection rates among species. However, we demonstrate that eDNA-based approaches can be used to track mammals of conservation concern, and reflect patterns of recent waterhole use and co-occurrence across water-dependent species, both of which are crucial for making evidence-based decisions regarding water management and provisioning.

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

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

Predictors of Mammalian Diversity in the New York Metropolitan Area

Urbanization can have profound consequences for mammalian biodiversity and is thought to contribute to patterns of species richness and community composition. Large cities can be particularly challenging environments for mammals because these habitats are often impacted by anthropogenic perturbations, including high human population density, fragmented habitats, and extensive human development. In this study, we investigated mammalian species richness, Shannon–Wiener diversity, and evenness in the most densely populated region in the United States: the New York metropolitan area. Specifically, we deployed camera traps from 2015 to 2019 to investigate six drivers of mammalian diversity across 31 greenspaces: (1) human population density, (2) patch size, (3) habitat type, (4) surrounding land cover, (5) geographical barriers to dispersal, and (6) habitat heterogeneity. We found that mammal community composition is largely influenced by a multitude of anthropogenic factors. Specifically, mammal species richness was higher in greenspaces with larger patch sizes and lower in greenspaces surrounded by more development. Moreover, Shannon–Wiener diversity and evenness were higher in urban natural landscapes than human-altered landscapes. In a subset of data that only included carnivores, we found that carnivore Shannon–Wiener diversity was higher in urban natural habitats and in sites with lower human population densities. Finally, we found that geographical barriers to dispersal contributed to both patterns of mammalian diversity and patterns of carnivore diversity: mammal taxa richness, Shannon–Wiener diversity, and evenness were all significantly higher on the continent (Bronx/Westchester) than on Long Island. These results suggest that preserving urban greenspaces is important for maintaining both mammalian and carnivore biodiversity and that management of mammals in cities should concentrate on maintaining large, connected, natural greenspaces.

Contrasting responses of native and introduced mammal communities to fire mosaics in a modified landscape.

Planned fire is increasingly recognized as an important tool in conservation, but other factors such as land-use change may hinder the ability of land managers to use fire for the benefit of biodiversity. The mosaic of past fires in native vegetation may interact with the mosaic of other land-cover types in human-modified landscapes, yet the effects of these interactions on mammal communities are unknown. We investigated the responses of ground-dwelling mammal community composition and species richness to interactions between land cover and post-fire vegetation growth-stage mosaics in southern Australia. This fire-prone, human-modified landscape features a fine-scale fire mosaic in native vegetation patches surrounded by pasture, horticulture, and peri-urban environments. We measured the composition of land-cover types and fire mosaics (landscape structure) at multiple scales of up to 1257 ha surrounding 129 study sites, and considered native and introduced species together and separately. Land-cover composition was the primary driver of community composition: native species favored areas with a greater proportion of native heathy woodland, whereas introduced species were associated with landscapes comprising more cleared land. The fire mosaic also influenced community composition and species richness: greater growth-stage diversity was associated with native habitat-specialist communities and fewer introduced species. In areas with more cleared land, native species richness increased when there was a greater proportion of mid-successional vegetation, demonstrating that the effect of fire mosaics on mammal diversity depended on land-cover composition. The positive relationship between introduced species richness and cleared land extent was also stronger in recently burned sites than in other growth stages, suggesting that introduced species are well suited to more modified areas of the landscape. Land managers need to consider the underlying land-cover composition and the potential interactions it may have with fire mosaics and species composition. In this landscape a greater diversity of growth stages may disadvantage introduced species yet an increase in mid-successional vegetation in more modified areas would be likely to benefit native mammal communities. Our study highlights that fire management may need to be tailored depending on the context of land use and the species of interest.