Response of neotropical bat assemblages to human land use

Wing morphology is related to niche specialization and interaction networks in stenodermatine bats (Chiroptera: Phyllostomidae)

Plant–animal interactions constitute some of the most important ecological processes for the maintenance of tropical forests. Bats are the only group of mammals capable of true flight and have been recognized as important dispersers of pioneer and secondary successional plant species. Although progress has been made in the study of Neotropical bats, morphological variation of the wing and its influence on niche separation between species is unknown. We evaluated relationships among habitat structures of selected Colombian tropical dry forest patches, the diet through interaction networks, and wing morphology of 11 species of bats in the Stenodermatinae subfamily (297 individuals) using geometric morphometry in a phylogenetic context. The results indicate that the phylogenetic signal for wing size is greater than for wing shape, thus providing some evidence for evolutionary convergence. Wing shape variation was associated primarily with the distal anatomical tip of the third finger and the joint between the humerus and the radius and ulna. Species with wide, short wings, as in the genus Artibeus had generalist diets and less nested positions within the interaction networks. In contrast, species with elongated and pointed wings, such as Sturnira and Platyrrhinus, had specialized diets and more nested positions within the interaction networks. We argue that wing shape variation may play an important role as a source of interspecific variation leading to food specialization within tropical bat communities.

From island biogeography to landscape and metacommunity ecology: A macroecological perspective of bat communities

The equilibrium theory of island biogeography and its quantitative consideration of origination and extinction dynamics as they relate to island area and distance from source populations have evolved over time and enriched theory related to many disciplines in spatial ecology. Indeed, the island focus was catalytic to the emergence of landscape ecology and macroecology in the late 20th century. We integrate concepts and perspectives of island biogeography, landscape ecology, macroecology, and metacommunity ecology, and show how these disciplines have advanced the understanding of variation in abundance, biodiversity, and composition of bat communities. We leverage the well-studied bat fauna of the islands in the Caribbean to illustrate the complex interplay of ecological, biogeographical, and evolutionary processes in molding local biodiversity and system-wide structure. Thereafter, we highlight the role of habitat loss and fragmentation, which is increasing at an accelerating rate during the Anthropocene, on the structure of local bat communities and regional metacommunities across landscapes. Bat species richness increases with the amount of available habitat, often forming nested subsets along gradients of patch or island area. Similarly, the distance to and identity of sources of colonization influence the richness, composition, and metacommunity structure of islands and landscape networks.

Common vampire bat (Desmodus rotundus) abundance and frequency of attacks to cattle in landscapes of Yucatan, Mexico

Desmodus rotundus is one of the wild animal species that has benefitted by habitat alteration and its population has increased due to livestock activities. Common vampire bat population management has been implemented across Mexico due to the economic losses to livestock production, inflicted by vampire bat attacks and rabies transmission. Yucatan is one of the seven most impacted states in Mexico by the number of cattle rabies cases per year. However, there is little research on D. rotundus populations such as the frequency and attack patterns to cattle. This study's objective was to analyze the relationship between D. rotundus abundance and number of bovines attacked in livestock landscapes in Yucatan. The study used data gathered by the State Committee for Protection and Promotion of Livestock in Yucatan through the National Campaign for Common Vampire Bat Population Control. Data collected from January 2014 to December 2017 was analyzed using Pearson correlation. Distribution maps on Desmodus rotundus abundance and number of bovines attacked were also created. Higher abundance of Desmodus rotundus and number of cattle attacks were observed in the central region of Yucatan, particularly in Izamal municipality. Positive correlations were found between (1) abundance of Desmodus rotundus and number of cattle in the region, (2) total number of cattle and number of cattle attacked, and (3) abundance of Desmodus rotundus and number of cattle attacked. We can conclude that there is a relationship between Desmodus rotundus abundance and frequency of cattle attacks in most municipalities across Yucatan. Some outstanding exceptions were observed, which require further detailed investigations.

Contrasting Effects of Chronic Anthropogenic Disturbance on Activity and Species Richness of Insectivorous Bats in Neotropical Dry Forest

For prioritizing conservation actions, it is vital to understand how ecologically diverse species respond to environmental change caused by human activity. This is particularly necessary considering that chronic human disturbance is a threat to biodiversity worldwide. Depending on how species tolerate and adapt to such disturbance, ecological integrity and ecosystem services will be more or less affected. Bats are a species-rich and functionally diverse group, with important roles in ecosystems, and are therefore recognized as a good model group for assessing the impact of environmental change. Their populations have decreased in several regions, especially in the tropics, and are threatened by increasing human disturbance. Using passive acoustic monitoring, we assessed how the species-rich aerial insectivorous bats—essential for insect suppression services—respond to chronic human disturbance in the Caatinga dry forests of Brazil, an area potentially harboring ca. 100 bat species (nearly 50% are insectivorous), but with > 60% its area composed of anthropogenic ecosystems under chronic pressure. Acoustic data for bat activity was collected at research sites with varying amounts of chronic human disturbance (e.g., livestock grazing and firewood gathering). The intensity of the disturbance is indicated by the global multi-metric CAD index (GMDI). Using Animal Sound Identifier (ASI) software, we identified 18 different bat taxon units. Using Hierarchical Modeling of Species Communities (HMSC), we found trends in the association of the disturbance gradient with species richness and bat activity: species richness was higher at sites with higher human disturbance, whereas bat activity decreased with increasing human disturbance. Additionally, we observed taxon-specific responses to human disturbance. We conclude that the effects of chronic anthropogenic disturbance on the insectivorous bat fauna in the Caatinga are not homogeneous and a species-specific approach is necessary when assessing the responses of local bats to human disturbances in tropical dry forests, and in other biomes under human pressure.

A database of common vampire bat reports

The common vampire bat (Desmodus rotundus) is a sanguivorous (i.e., blood-eating) bat species distributed in the Americas from northern Mexico southwards to central Chile and Argentina. Desmodus rotundus is one of only three mammal species known to feed exclusively on blood, mainly from domestic mammals, although large wildlife and occasionally humans can also serve as a food source. Blood feeding makes D. rotundus an effective transmissor of pathogens to its prey. Consequently, this species is a common target of culling efforts by various individuals and organizations. Nevertheless, little is known about the historical distribution of D. rotundus. Detailed occurrence data are critical for the accurate assessment of past and current distributions of D. rotundus as part of ecological, biogeographical, and epidemiological research. This article presents a dataset of D. rotundus historical occurrence reports, including >39,000 locality reports across the Americas to facilitate the development of spatiotemporal studies of the species. Data are available at 10.6084/m9.figshare.15025296.

Measurement(s)	occurrence report
Technology Type(s)	digital curation
Sample Characteristic - Organism	Desmodus rotundus
Sample Characteristic - Location	North America • South America

Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.18745316

A multifaceted approach to understanding bat community response to disturbance in a seasonally dry tropical forest

Given widespread habitat degradation and loss, reliable indicators are needed that provide a comprehensive assessment of community response to anthropogenic disturbance. The family Phyllostomidae (Order Chiroptera) has frequently been the focus of research evaluating bats' response to habitat disturbance in seasonally dry tropical forests (SDTFs). However, few studies compare this family to the larger bat assemblage to assess its efficacy as a bioindicator. We compared community and species-specific attributes of understory phyllostomid and all understory bat species: (1) along a gradient of habitat disturbance within a human-modified SDTF landscape; and (2) between forest and riparian habitats within each disturbance level. We captured 290 individuals belonging to 13 species and 4 families. Phyllostomid species exhibited greater sensitivity to disturbance than the understory bat community as a whole based on richness and beta diversity. Both groups were more sensitive to disturbance in forest than riparian habitat, but phyllostomid species were more likely to be lost from highly disturbed forest habitat. The two dominant species declined in abundance with disturbance but variation in body condition was species-specific. These results suggest that Phyllostomidae are more effective indicators of human disturbance in SDTF than the understory bat community as a whole and evaluation of bats' response to disturbance is best accomplished with a multifaceted approach.

Fragmentation does not affect gene flow in forest populations of the dusky pipistrelle bat on the eastern seaboard of South Africa

The Eastern Cape Province harbors almost half of the indigenous forest in South Africa, but these forests are threatened by large-scale agricultural and urban development planned for the coming decade. Additional anthropogenic development is likely to cause further fragmentation and degradation of forests inhabited by the dusky pipistrelle bat (Pipistrellus hesperidus). We used eight microsatellite markers to study the genetic diversity, population structure, and migration, of P. hesperidus (n = 120) across 14 sites in the Eastern Cape and KwaZulu-Natal provinces of South Africa. We examined the effect of contemporary land cover types on genetic differentiation to assess whether current levels of urbanization and agricultural development affect gene flow. High gene flow and low population structure were evident across sampled sites, apart from genetic discontinuities at the northern (Oribi Gorge Nature Reserve) and southern (Alexandria Forest) ends of the seaboard. Genetic discontinuity at Oribi Gorge may relate to anthropogenic modification of two rivers surrounding the forest, while the Alexandria-linked barrier is a climatic break known as the Bedford gap. Migration rates generally were low between sites except for one Scarp forest, Manubi State Forest, from which individuals dispersed to other sites. The Amatole Mistbelt forests supported high genetic diversity, and likely served as a refugium for P. hesperidus during the Last Glacial Maximum. The composition of land cover classes between sites was a poor predictor of genetic differentiation, although it seems likely that P. hesperidus uses riparian habitats and wetlands for dispersal. Lastly, urban and agricultural development did not have a significant effect on genetic differentiation, which may reflect the wide niche breadth and intermediate distribution range of the species. This study provides insights into genetic diversity and gene flow of P. hesperidus across the study region prior to agricultural intensification and large-scale urbanization.

Dimensions of Phyllostomid Bat Diversity and Assemblage Composition in a Tropical Forest-Agricultural Landscape

Tropical rainforests are suffering rapid habitat loss with large extensions of land transformed into agriculture. We wanted to know whether the type of agricultural activity in forest-agricultural landscapes affects how species composition as well as taxonomic and functional dimensions of diversity respond. We worked in the Amazon forests of southeast Peru and used bats as model organisms. We sampled mosaics characterized by forest adjacent to papaya plantations or cattle pastures. At each sampling site we established a transect in each of the three different vegetation types: forest interior, forest edge and agricultural land. We found that vegetation type was a better predictor of species composition than the type of agricultural land present. Vegetation structure characteristics explained differences in bat species composition between forest interior and edge. Agricultural land type chosen was not irrelevant as we found higher estimated species richness in papaya than in pasture sites. Agricultural land type present in a site and vegetation type affected functional diversity, with both agricultural land types showing a lower number of functionally distinct species than forests. We found papaya plantation sites showed species more evenly dispersed in trait space, suggesting they do better at conserving functional diversity when compared to cattle pasture sites. We demonstrate that sites that harbor agricultural activities can maintain a considerable proportion of the expected bat diversity. We note that this region still has large tracts of intact forest adjacent to agricultural lands, which may explain their ability to maintain relatively high levels bat diversity.

Effects of Forest Fragmentation on the Vertical Stratification of Neotropical Bats

Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional forest space, studies are biased towards understory-based surveys and only few assessments of vertical stratification were done in fragmented landscapes. Using both ground and canopy mist-nets, we investigated how the vertical structure of bat assemblages is influenced by forest fragmentation in the experimentally fragmented landscape of the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Over a three year-period, we captured 3077 individuals of 46 species in continuous forest (CF) and in 1, 10 and 100 ha forest fragments. In both CF and forest fragments, the upper forest strata sustained more diverse bat assemblages than the equivalent understory layer, and the midstory layers had significantly higher bat abundance in fragments than in CF. Artibeus lituratus and Rhinophylla pumilio exhibited significant shifts in their vertical stratification patterns between CF and fragments (e.g., R. pumilio was more associated with the upper strata in fragments than in CF). Altogether, our study suggests that fragmentation modulates the vertical stratification of bat assemblages.

Bat Ensembles Differ in Response to Use Zones in a Tropical Biosphere Reserve

Biosphere reserves, designated under The United Nations Education, Scientific and Cultural Organization’s (UNESCO) Man and Biosphere Programme, aim to sustainably integrate protected areas into the biological and economic landscape around them by buffering strictly protected habitats with zones of limited use. However, the effectiveness of biosphere reserves and the contribution of the different zones of use to protection is poorly known. We assessed the diversity and activity of bats in the Crocker Range Biosphere Reserve (CRBR) in Sabah, Malaysia, using harp traps, mist nets and acoustic surveys in each zone—core, buffer, transition and in agricultural plots outside of the reserve. We captured 30 species, bringing the known bat fauna of CRBR to 50 species, half of Borneo’s bat species. Species composition and acoustic activity varied among zones and by foraging ensemble, with the core and buffer showing particular importance for conserving forest-dependent insectivorous bats. Frugivorous bats were found in all zones but were the most abundant and most species-rich ensemble within agricultural sites. Although sampling was limited, bat diversity and activity was low in the transition zone compared to other zones, indicating potential for management practices that increase food availability and enhance biodiversity value. We conclude that, collectively, the zones of the CRBR effectively protect diversity, but the value of the transition zone can be improved.

Responses of Phyllostomid Bats to Traditional Agriculture in Neotropical Montane Forests of Southern Mexico

Bat communities' responses to land use change in neotropical montane forests have scarcely been studied. We hypothesized that, like in lowland forests, a montane agricultural area will have a lower species richness, abundance, diversity and species composition of understory phyllostomid bats than a native forest (montane cloud forest and pine-oak forest). Monthly surveys over the course of a year gave an overall low species richness and abundance (167 captures corresponding to nine species). We found a slight loss of species richness in agricultural areas with respect to the montane cloud forest (one species) and pine-oak forest (two species). However, differences in abundance were noteworthy: 45% and 73% fewer captures in agricultural areas than in the montane cloud forest and pine-oak forest, respectively. Species diversity was higher in the montane cloud forest than the pine-oak forest, but the diversity of agricultural areas did not differ between the types. Species and guild compositions did not differ between crops and forests. At least for the understory phyllostomid bats, and at the spatial scale studied, traditional management of agricultural areas in the study area and the surrounding matrix could explain the similarity in species richness, composition, and diversity between the agricultural area and native montane forests; however, other indicator groups should be evaluated to understand the effects of habitat loss on montane forests.

Do riparian forest strips in modified forest landscapes aid in conserving bat diversity?

Agricultural practices lead to losses of natural resources and biodiversity. Maintaining forests alongside streams (riparian forest strips) has been used as a mechanism to minimize the impact of clearing for agriculture on biodiversity. To test the contribution of riparian forest strips to conserve biodiversity in production landscapes, we selected bats as a biodiversity model system and examined two dimensions of diversity: taxonomic and functional. We compared bat diversity and composition in forest, with and without stream habitat, and in narrow forest riparian strips surrounded by areas cleared for agriculture. We tested the hypothesis that riparian forest strips provide potential conservation value by providing habitat and serving as movement corridors for forest bat species. Riparian forest strips maintained 75% of the bat species registered in forested habitats. We found assemblage in sites with riparian forest strips were dominated by a few species with high abundance and included several species with low abundance. Bat species assemblage was more similar between sites with streams than between those sites to forests without stream habitat. These results highlight the importance of stream habitat in predicting presence of bat species. We registered similar number of guilds between forest sites and riparian forest strips sites. Relative to matrix habitats, stream and edge habitats in riparian forest strips sites were functionally more diverse, supporting our hypothesis about the potential conservation value of riparian forest strips. Results from this study suggest that maintaining riparian forest strips within cleared areas for agricultural areas helps conserve the taxonomic and functional diversity of bats. Also, it provides basic data to evaluate the efficacy of maintaining these landscape features for mitigating impacts of agricultural development on biodiversity. However, we caution that riparian forest strips alone are not sufficient for biodiversity maintenance; their value depends on maintenance of larger forest areas in their vicinity.

Guild-level responses of bats to habitat conversion in a lowland Amazonian rainforest: species composition and biodiversity

Landscape modification represents one of the most severe threats to biodiversity from local to global scales. Conversion of forest to agricultural production generally results in patches of habitat that subdivide or isolate populations, alter the behavior of species, modify interspecific interactions, reduce biodiversity, and compromise ecosystem processes. Moreover, conversion may increase exposure of humans to zoonoses to which they would otherwise rarely be exposed. We evaluated the effects of forest conversion to agriculture, and its subsequent successional dynamics, on bat communities in a region of the Amazon that was predominantly closed-canopy rainforest. Based on a nonmanipulative experiment, we quantified differences in species composition, community structure, and taxonomic biodiversity among closed-canopy forest (bosque), agricultural lands (chacra), and secondary forest (purma) for two phyllostomid guilds (frugivores and gleaning animalivores) during the wet and dry seasons. Responses were complex and guild-specific. For frugivores, species composition (species abundance distributions) differed between all possible pairs of habitats in both wet and dry seasons. For gleaning animalivores, species composition differed between all possible pairs of habitats in the dry season, but no differences characterized the wet season. Ecological structure (rank abundance distributions) differed among habitats in guild-specific and season-specific manners. For frugivores, mean diversity, evenness, and dominance were greater in bosque than in purma; mean dominance was greater in bosque than in chacra, but local rarity was greater in chacra than in bosque, and no differences were manifest between purma and chacra. For gleaning animalivores, mean diversity and evenness were greater in bosque than in purma, but no differences were manifest between chacra and bosque, or between purma and chacra. Such results have important implications for management, conservation, and the epidemiology of zoonotic diseases. La actual modificación del paisaje, a escalas que van de lo local a lo global, es una de las amenazas más severas a la biodiversidad. De manera general, la conversión de bosques a áreas agrícolas produce parches de hábitat que subdividen o aíslan poblaciones, alteran la conducta de las especies, modifican las interacciones interespecíficas, reducen la biodiversidad y comprometen las funciones de los ecosistemas. Más aún, la transformación de estos ambientes puede incrementar la probabilidad de que las poblaciones humanas interactúen con zoonosis con las que de otra manera raramente entrarían en contacto. Evaluamos los efectos de la conversión de hábitat en comunidades de murciélagos en una región de Amazonia en la que la vegetación dominante es un bosque lluvioso de copas cerradas, y en la cual los efectos de la conversión a usos agrícolas sobre la biodiversidad, y la subsecuente dinámica sucesional, son aún poco comprendidos. Por medio de un experimento no-manipulativo, cuantificamos las diferencias en composición de especies, estructura de la comunidad y diversidad taxonómica entre bosque cerrado (bosque), áreas agrícolas (chacra) y bosque secundario (purma) para dos gremios tróficos de murciélagos filostómidos (frugívoros y forrajeadores de sustrato) durante dos temporadas (secas y lluvias). Las respuestas fueron complejas y diferentes para cada gremio. Para los frugívoros, la composición de especies (distribución de las abundancias) fue diferente para todos los posibles pares de hábitats tanto para secas como para lluvias. Para los forrajeadores de sustrato, la composición de especies difirió entre todos los posibles pares de hábitats en la temporada seca, pero no en la de lluvias. La estructura ecológica (distribuciones rango-abundancia) fue también específica para gremios y temporadas. Para los frugívoros, la diversidad promedio, equidad y dominancia fueron mayores en bosque que en purma; la dominancia promedio fue mayor en bosque que en chacra, pero la rareza local fue mayor en chacra que en bosque, y no se encontraron diferencias entre purma y chacra. Para los forrajeadores de sustrato, la diversidad promedio y la dominancia fueron mayores en bosque que en purma, pero no se detectaron diferencias entre chacra y bosque, o entre purma y chacra. Estos resultados tienen importantes implicaciones para el manejo, conservación y epidemiología de zoonosis.

Effects of a wind farm installation on the understory bat community of a highly biodiverse tropical region in Mexico

Wind energy has rapidly become an important alternative among renewable energies, and it is generally considered clean. However, little is known about its impact at the level of ecological communities, especially in biodiversity hotspots. The Isthmus of Tehuantepec is a highly biodiverse region in Mesoamerica, and has the highest potential for generating wind energy in Mexico. To assess the effects of installing a wind farm on the understory bat community in a landscape of fragmented habitat, we assessed its diversity and composition over four stages of installation (site preparation, construction, and two stages of operation). We captured 919 bats belonging to 22 species. Species richness, functional diversity and phylogenetic diversity decreased during construction and the first stage of operation. However, these components of biodiversity increased during the second stage of operation, and species composition began to resemble that of the site preparation stage. No species considered as sensitive to disturbance was recorded at any stage. This is the first study to reveal the diversity of a Neotropical bat community after wind turbines begin to operate.

Deforestation Impacts on Bat Functional Diversity in Tropical Landscapes

Functional diversity is the variability in the functional roles carried out by species within ecosystems. Changes in the environment can affect this component of biodiversity and can, in turn, affect different processes, including some ecosystem services. This study aimed to determine the effect of forest loss on species richness, abundance and functional diversity of Neotropical bats. To this end, we identified six landscapes with increasing loss of forest cover in the Huasteca region of the state of Hidalgo, Mexico. We captured bats in each landscape using mist nets, and calculated functional diversity indices (functional richness and functional evenness) along with species richness and abundance. We analyzed these measures in terms of percent forest cover. We captured 906 bats (Phyllostomidae and Mormoopidae), including 10 genera and 12 species. Species richness, abundance and functional richness per night are positively related with forest cover. Generalized linear models show that species richness, abundance and functional richness per night are significantly related with forest cover, while seasonality had an effect on abundance and functional richness. Neither forest cover nor season had a significant effect on functional evenness. All these findings were consistent across three spatial scales (1, 3 and 5 km radius around sampling sites). The decrease in species, abundance and functional richness of bats with forest loss may have implications for the ecological processes they carry out such as seed dispersal, pollination and insect predation, among others.

Environmental and spatial drivers of taxonomic, functional, and phylogenetic characteristics of bat communities in human-modified landscapes

Background

Assembly of species into communities following human disturbance (e.g., deforestation, fragmentation) may be governed by spatial (e.g., dispersal) or environmental (e.g., niche partitioning) mechanisms. Variation partitioning has been used to broadly disentangle spatial and environmental mechanisms, and approaches utilizing functional and phylogenetic characteristics of communities have been implemented to determine the relative importance of particular environmental (or niche-based) mechanisms. Nonetheless, few studies have integrated these quantitative approaches to comprehensively assess the relative importance of particular structuring processes.

Methods

We employed a novel variation partitioning approach to evaluate the relative importance of particular spatial and environmental drivers of taxonomic, functional, and phylogenetic aspects of bat communities in a human-modified landscape in Costa Rica. Specifically, we estimated the amount of variation in species composition (taxonomic structure) and in two aspects of functional and phylogenetic structure (i.e., composition and dispersion) along a forest loss and fragmentation gradient that are uniquely explained by landscape characteristics (i.e., environment) or space to assess the importance of competing mechanisms.

Results

The unique effects of space on taxonomic, functional and phylogenetic structure were consistently small. In contrast, landscape characteristics (i.e., environment) played an appreciable role in structuring bat communities. Spatially-structured landscape characteristics explained 84% of the variation in functional or phylogenetic dispersion, and the unique effects of landscape characteristics significantly explained 14% of the variation in species composition. Furthermore, variation in bat community structure was primarily due to differences in dispersion of species within functional or phylogenetic space along the gradient, rather than due to differences in functional or phylogenetic composition.

Discussion

Variation among bat communities was related to environmental mechanisms, especially niche-based (i.e., environmental) processes, rather than spatial mechanisms. High variation in functional or phylogenetic dispersion, as opposed to functional or phylogenetic composition, suggests that loss or gain of niche space is driving the progressive loss or gain of species with particular traits from communities along the human-modified gradient. Thus, environmental characteristics associated with landscape structure influence functional or phylogenetic aspects of bat communities by effectively altering the ways in which species partition niche space.

Threshold effect of habitat loss on bat richness in cerrado-forest landscapes

Understanding how animal groups respond to contemporary habitat loss and fragmentation is essential for development of strategies for species conservation. Until now, there has been no consensus about how landscape degradation affects the diversity and distribution of Neotropical bats. Some studies demonstrate population declines and species loss in impacted areas, although the magnitude and generality of these effects on bat community structure are unclear. Empirical fragmentation thresholds predict an accentuated drop in biodiversity, and species richness in particular, when less than 30% of the original amount of habitat in the landscape remains. In this study, we tested whether bat species richness demonstrates this threshold response, based on 48 sites distributed across 12 landscapes with 9-88% remaining forest in Brazilian cerrado-forest formations. We also examined the degree to which abundance was similarly affected within four different feeding guilds. The threshold value for richness, below which bat diversity declines precipitously, was estimated at 47% of remaining forest. To verify if the response of bat abundance to habitat loss differed among feeding guilds, we used a model selection approach based on Akaike's information criterion. Models accounted for the amount of riparian forest, semideciduous forest, cerrado, tree plantations, secondary forest, and the total amount of forest in the landscape. We demonstrate a nonlinear effect of the contribution of tree plantations to frugivores, and a positive effect of the amount of cerrado to nectarivores and animalivores, the groups that responded most to decreases in amount of forest. We suggest that bat assemblages in interior Atlantic Forest and cerrado regions of southeastern Brazil are impoverished, since we found lower richness and abundance of different groups in landscapes with lower amounts of forest. The relatively higher threshold value of 47% suggests that bat communities have a relatively lower resistance to habitat degradation than other animal groups. Accordingly, conservation and restoration strategies should focus on increasing the amount of native vegetation of landscapes so as to enhance species richness of bats.

Individual-area relationship best explains goose species density in wetlands

Explaining and predicting animal distributions is one of the fundamental objectives in ecology and conservation biology. Animal habitat selection can be regulated by top-down and bottom-up processes, and is mediated by species interactions. Species varying in body size respond differently to top-down and bottom-up determinants, and hence understanding these allometric responses to those determinants is important for conservation. In this study, using two differently sized goose species wintering in the Yangtze floodplain, we tested the predictions derived from three different hypotheses (individual-area relationship, food resource and disturbance hypothesis) to explain the spatial and temporal variation in densities of two goose species. Using Generalized Linear Mixed Models with a Markov Chain Monte Carlo technique, we demonstrated that goose density was positive correlated with patch area size, suggesting that the individual area-relationship best predicts differences in goose densities. Moreover, the other predictions, related to food availability and disturbance, were not significant. Buffalo grazing probably facilitated greater white-fronted geese, as the number of buffalos was positively correlated to the density of this species. We concluded that patch area size is the most important factor determining the density of goose species in our study area. Patch area size is directly determined by water levels in the Yangtze floodplain, and hence modifying the hydrological regimes can enlarge the capacity of these wetlands for migratory birds.

Structure and diversity of phyllostomid bat assemblages on riparian corridors in a human-dominated tropical landscape

Tropical forests around the world have been lost, mainly because of agricultural activities. Linear elements like riparian vegetation in fragmented tropical landscapes help maintain the native flora and fauna. Information about the role of riparian corridors as a reservoir of bat species, however, is scanty. We assessed the value of riparian corridors on the conservation of phyllostomid bat assemblage in an agricultural landscape of southern Mexico. For 2 years (2011-2013), mist-netting at ground level was carried out twice during the dry season (December to May) and twice during the wet season (June to November) in different habitats: (1) riparian corridors in mature forest, (2) riparian corridors in pasture, (3) continuous forest away from riparian vegetation, and (4) open pastures. Each habitat was replicated three times. To determine the influence of vegetation structure on bat assemblages, all trees (≥10 cm dbh) were sampled in all habitats. Overall, 1752 individuals belonging to 28 species of Phyllostomidae were captured with Sternodermatinae being the most rich and abundant subfamily. Riparian corridors in mature forest and pastures had the greatest species richness and shared 65% of all species. Open pastures had the lowest richness and abundance of bats with no Phyllostominae species recorded. Six of the 18 species recorded could be considered as habitat indicators. There was a positive relationship between bat species composition and tree basal area. Our findings suggest that contrary to our expectations, bats with generalist habits and naturally abundant could be useful detector taxa of habitat modification, rather than bats strongly associated with undisturbed forest. Also in human-dominated landscapes, the maintenance of habitat elements such as large trees in riparian corridors can serve as reservoirs for bat species, especially for those that are strongly associated with undisturbed forest.