Article

Response of bat activity to land cover and land use in savannas is scale-, season-, and guild-specific

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Abstract

Tropical savannas are biomes of global importance under severe pressure from anthropogenic change, including land-cover and land-use change. Bats, the second-most diverse group of mammals, are critical to ecosystem functioning, but vulnerable to such anthropogenic stresses. There is little information on how savanna bats respond to land cover and land use, especially in Africa, limiting our ability to develop conservation strategies for bats and maintain the ecosystem functions and services they provide in this biome. Using acoustic monitoring , we measured guild-specific (aerial, edge, and clutter forager) responses of bat activity to both fine-scale vegetation structure and landscape-scale land-cover composition and configuration across the wet and dry seasons in a southern African savanna undergoing rapid land-cover and land-use change. Responses were guild-and season-specific but generally stronger in the dry season. Aerial and clutter bats responded most strongly to landscape metrics in the dry season (positive responses to savanna fragmentation and water cover, respectively) but fine-scale metrics in the wet season (positive responses to water cover and grass cover, respectively). Edge bats responded most strongly (negatively) to the distance to water in the dry season and fine-scale shrub cover in the wet season. Our results show it is possible to maintain high levels of bat activity in savanna mosaics comprised of different land covers and land uses. Bats, and the ecosystem services they provide, can be conserved in these changing landscapes, but strategies to do so must consider foraging guild, spatial scale, and seasonal variation in bat activity.

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... Based on studies from other parts of the world, it was expected that natural vegetation and corridors would benefit both farmers and the surrounding biodiversity, including bats (Park, 2015;Crisol-Martínez, Ford, Finbarr, Brown & Wormington, 2016;Heim et al., 2017;Kahnonitch et al., 2018;Rodríguez-San Pedro et al., 2019). Within South Africa, recent studies have found significant influences of land-cover and land-use on bat activity (Shapiro, Monadjem, Röder & McCleery, 2020). Therefore, we also expected that bat activity (especially of the clutter and clutter-edge guilds -see below) would be higher in areas close to natural vegetation (Weier et al., 2018). ...
... For statistical purposes, frequency band groups were grouped into three foraging guild groups according to Denzinger & Schnitzler (2013), Shapiro et al. (2020) and Monadjem et al. (2010Monadjem et al. ( , 2020 which were based on wing morphology, echolocation and foraging ecology and used for further analysis. These include aerial foragers (families Molossidae and Emballonuridae), clutteredge foragers (families Vespertilionidae and Miniopteridae) and clutter foragers (families Rhinolophidae and Hipposideridae). ...
... Significant results (P < 0.05) shown in bold. tation provide good structural elements that are ideal for the clutter-edge guild as the bats forage over vegetation edges and near the natural vegetation on the farm edge (Shapiro et al., 2020). Some insect pests such as heteropterans, favour apical regions of the trees, the orchard edges also provide easy access to macadamia insect pests for bats during certain times of the year when these pest insects are present in high numbers (Schoeman, 2014(Schoeman, , 2016. ...
... Bat species respond differently to the same landscape matrix and show varying levels of sensitivity to habitat destruction, light pollution and other human-induced stressors (Frey-Ehrenbold et al., 2013;Mtsetfwa et al., 2018;Rowse et al., 2016;Russo and Ancillotto, 2015;Shapiro et al., 2019). This varying response is related to their foraging ecology, where three general foraging guilds can be recognised. ...
... Pinaud et al., 2018). However, even open-air feeders, which can be found to exploit monocultures such as southern African sugarcane plantations as foraging grounds, can be affected by the loss of roost sites or alternative prey species abundances (Shapiro et al., 2019). Agricultural monocultures can also cause loss of functional diversity, for example, specialised insectivores are absent from bird communities in cocoa plantations in Cameroon (Jarrett et al., in press). ...
... Lower levels of activity for both edge space and open space aerial foraging guilds in the dry season can be explained by lower prey availability and pest insect abundances (Taylor et al., 2013a;Weier et al., 2018), but may also be due to colder temperatures in winter (Monadjem et al., 2020;Parker and Bernard, 2018). We cannot confirm observations of Shapiro et al. (2019), who found a seasonal dependence of narrow space foraging bats on sugarcane, which could possibly be explained by water availability. Since our study area is within a particularly high rainfall area with the mountain range providing many perennial streams, the artificial water bodies on farmland might be less of an attraction to local bats. ...
Article
Bats have been shown to provide successful pest suppression in different land-use systems globally. Recent research demonstrates high economic values of pest suppression by bats also in macadamia orchards, which is enhanced by natural habitat patches at orchard edges. We investigated the impact of the conversion of natural to agricultural (macadamia-dominated) habitats. Using ~65,000 recorded bat call sequences; we studied bat communities in three land use types: a nature reserve, macadamia orchards with and without adjacent natural habitat patches. All study sites are situated on the southern slopes of the Soutpansberg, northern South Africa. Species richness varied significantly between the nature reserve and the macadamia orchards, but did not between orchards with and without neighbouring natural habitat. Within the orchards, activity of edge space foraging (dependent on e.g. forest edges) bats was greater at natural edges, whereas open space aerial foraging species (hunting above canopy) were more active at human-modified edges. Although seven narrow space foraging (i.e. dense vegetation dependent) bat species were identified at both orchard and reserve, this foraging guild occurred more frequently in the nature reserve (2.9-4.1% of all call sequences) than in the orchards (0.5-2.9% of all call sequences). Narrow space foraging bats were thus largely excluded from simplified agricultural landscapes, in particular where natural edge habitats are missing, compared to our natural control. The current trend in conversion of natural habitat in favour of macadamia monocultures, especially if remnant natural patches at orchard boundaries are removed, will have widespread detrimental effects on bat diversity. The resulting reduced biological pest suppression by bats and increased reliance on chemical control may further exacerbate biodiversity declines.
... Southern African savannas support a rich diversity of bats (Gelderblom et al., 1995;Monadjem et al., 2010aMonadjem et al., , 2010b. Bat community structure in savannas has been shown to be shaped by both abiotic and biotic factors acting at local and regional scales (Weier et al., 2016;Schoeman and Monadjem, 2018), as well as by land use and climate change (Taylor et al, 2013b;Smith et al., 2016;Foord et al., 2018;Mtset fwa et al., 2018;Weier et al., 2018;Shapiro et al., 2019). ...
... The attraction of water bodies to bats in southern African agricultural-savanna mosaic landscapes is guild-, season-and scale-specific (Weier et al., 2018;Shapiro et al., 2019). For example, in the lowlying savanna region of Eswatini, in the dry season (but not the wet season), activity of clutter-feeding and clutter-edge bats (but not open-air feeders) responded positively to water (Shapiro et al., 2019). ...
... The attraction of water bodies to bats in southern African agricultural-savanna mosaic landscapes is guild-, season-and scale-specific (Weier et al., 2018;Shapiro et al., 2019). For example, in the lowlying savanna region of Eswatini, in the dry season (but not the wet season), activity of clutter-feeding and clutter-edge bats (but not open-air feeders) responded positively to water (Shapiro et al., 2019). In a dry deciduous forest in central western Madagascar, bat activity at pools within a riverbed were significantly higher than forest and dry riparian habitats, but only for Vespertilionidae (clutter-edge) and Hipposideridae (clutter-feeding) bats, not for openair-feeding Molossidae (Bader et al., 2015). ...
Article
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Although the Limpopo River is not perennial in its upper stretches in South Africa, the presence of a narrow riparian forest zone is expected to enhance bat diversity by promoting a wider range of foraging types, but the scale at which this effect may operate is not known. A recent, fine-scale model of bat diversity in Africa suggested that rivers may enhance species richness of bats, but that strong gradients in richness would occur next to rivers especially in savanna areas. We tested this idea by conducting acoustic surveys with bat detectors around six water bodies at distances from 0−12 km from the Limpopo River in two adjacent protected areas, the Mapungubwe National Park and the Venetia Limpopo Nature Reserve. We used a paired design, with each water body having detectors placed at and just away (500-750 m) from it. We found enhanced species richness, diversity and activity at MNP sites closer to the Limpopo (0-5 km) compared with VNR sites located 9−12 km from the Limpopo. Moreover, at VNR but not MNP, the bat community was dominated (32% of calls) by an arid-adapted generalist species, the Cape serotine (Neoromica capensis). Consistent with the proximity of structurally complex riparian vegetation, slow flying, clutter-feeding horseshoe bats (Rhinolophus spp.) were relatively more abundant (12% of calls) at MNP compared with VNR (0.7% of calls). This effect was highly accentuated when correcting for detectability of different species to bat detectors. Proximity to small, natural and artificial water bodies significantly enhanced both species richness and activity, but this effect was much more pronounced at sites > 5 km from the Limpopo compared with sites < 2 km from the Limpopo. We conclude that while major rivers with riparian zones can exert a significant impact on species richness, diversity, activity and community structure of insectivorous bats, this effect may only extend a few kilometres from the river. Protection of riparian zones along rivers in savannas is therefore critical to conserving intact and diverse bat communities.
... Bats provide a range of ecological functions as seed dispersers and arthropod pest suppressors , are easily monitored (Jones et al., 2009) (Moir et al., 2020b). Insectivorous bats are split into three guilds based on their preferred foraging landscape: Clutter (dense forest areas/vegetation), Clutter-edge (mixed dense and more open vegetation areas, particularly forest edges), and Open-air (out of forests/vegetated areas) (Fenton, 1990;Weier et al., 2018;Shapiro et al., 2020). The guilds exhibit different eco-morphological characteristics and vocalization parameters to adapt to their preferred foraging spaces (Fenton, 1990). ...
... The ve open-air foragers recorded in abandoned elds are classi ed as urban-exploiter species (Marsden et al. 2023), so they may be pre-adapted to landscapes inhabited and modi ed by humans. Mops midas was an unexpected occurrence and is a putative range extension for this species (Monadjem et al., 2020). The former elds, now predominantly comprising Vachellia karoo woodland, provide suitable habitat not only for clutter-edge species but for the clutter species, Rhinolophus clivosus, as found in previous savanna-woodlandstudies (Csorba et al., 2003;Stoffberg et al., 2012). ...
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Deagrarianisation (cropland, field abandonment) is a widespread global phenomenon with high potential for carbon sequestration and for reversing biodiversity extinction debt thus promoting environmental sustainability and conservation. To date, much work on this topic has focused on plant succession and associated plant diversity, but few studies have considered faunal communities, particularly in Africa. Here we used passive acoustic monitoring to record insectivorous bat communities within forest fragments and former fields under communal land tenure in the Transkei region (Eastern Cape) of South Africa. Insectivorous bat diversity of fields, abandoned in the 1960s to 1980s, resembling late stages of succession, were compared to fragments of Transkei Coastal Scarp forest embedded within the landscape. We found that former fields hosted 14 species from 11 genera, comprising greater species richness, activity, Shannon-Weiner diversity, and functional diversity, irrespective of age, as compared to the forest fragments. Furthermore, the former fields exhibited comparable species richness to, and higher functional diversity than, three large neighbouring intact Transkei Scarp forests. Interestingly, the time since cultivation had ceased (35—64 years ago) had no measurable effect on species and functional diversity. Former fields are dominated by the invasive alien shrub Lantana camara and the indigenous pioneer tree Vachellia karoo , but nonetheless in terms of insectivorous bats, these landscapes have a conservation value as they are diverse both in terms of species and function. Mutual mechanisms to enhance both biodiversity conservation and the utility of the land to local communities should be further considered.
... The complexity of vegetation strata drives distribution patterns of different species and their diversity locally and on a broader scale (Díaz et al. 2005;Guo et al. 2021;Marques et al. 2016;Moudrý et al. 2023). This horizontal and vertical mapping is crucial for decision-makers to develop sustainable policies to enhance the resilience of biodiversity and ecosystem services (Lehrer et al. 2021;Starbuck et al. 2014;Weller 2008), especially in cultural landscapes where horizontal structure encompasses remnants of natural forests, croplands, agroforestry systems, and tree plantations (Shapiro et al. 2020). ...
... Occupancy for N. leisleri displayed a positive quadratic relationship with the shrubland proportion Figure 5). This species can be found in various habitats, favoring forested habitats with lower levels of vegetation clutter, especially for foraging (Ferreira et al. 2022;Shapiro et al. 2020). P. pygmaeus stood out as the sole species with a positive occupancy association concerning other land cover types, precisely edge density of built-up areas, agriculture, and water bodies ( Figure 5). ...
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Anthropogenic activities have significantly altered land cover on a global scale. These changes often have a negative effect on biodiversity limiting the distribution of species. The extent of the effect on species’ distribution depends on the landscape composition and configuration at a local and landscape level. To better understand this effect on a large scale, we evaluated how land cover and vegetation structure shape bat species’ occurrence while considering species’ imperfect detection. We hypothesize that intensification of anthropogenic activities in agriculture, for example, reduces heterogeneity of land cover and vegetation structure, and thereby, limits bat occurrence. To investigate this, we conducted acoustic bat sampling across 59 locations in southern Portugal, each with three spatial replicates. We derived fine-scale vegetation structural metrics by combining spaceborne LiDAR (GEDI) and synthetic aperture radar data (Sentinel-1 and ALOS/PALSAR-2). Additionally, we included land cover metrics and high-resolution climate data from CHELSA. Our findings revealed an important relationship between bat species’ occupancy and vegetation structure, particularly with vegetation canopy height. Moreover, forest and shrubland proportions were the main land cover types influencing bat species responses. All species’ best-ranking occupancy models included at least one climatic variable (temperature, humidity, or potential evapotranspiration), demonstrating the importance of climate when predicting bat distribution. Our acoustic surveys had a species’ detection probability varying from 0.19 to 0.86, and it was influenced by night conditions. These findings underscore the importance of modeling imperfect detection, especially for highly vagile and elusive organisms like bats. Our results demonstrate the effectiveness of using vegetation and landscape metrics derived from high-resolution remote sensing data to model species distribution in the context of biodiversity monitoring and conservation.
... As found by Weier et al. (2018), the abundance of insects and water availability had an influence on the abundance of species (Crisol-Martínez et al. 2016). Water availability, for both foraging and drinking, through artificial water sources such as dams can also increase the activity and diversity of bats in other agroecosystems (Shapiro et al. 2020;Sirami et al. 2013). Bats seem to prefer polyculture or organic agroecosystems (Kelly et al. 2016;Wickramasinghe et al. 2003;Wordley et al. 2017). ...
... However, most of the agroecological studies on bats are currently focusing on common insectivorous species and it is worth mentioning that rare clutter feeding species such as the Rhinolophidae might also have a key role in suppressing certain pest insect species (Russo et al. 2018). From studies conducted in southern African agroecosystems these species seem to be already affected considerably by the ongoing land-use change and possibly also the competition and displacement by more generalist species as they have been recorded in very low numbers in more intensive agroecosystems (Linden et al. 2019;Shapiro et al. 2020;Weier et al. 2018Weier et al. , 2021. While, many (but not all) species of the open air and clutter edge feeding guilds of bats do use anthropogenic structures (such as tunnels, bridges, and roofs) for roosting the rhinolophids most commonly require their habitat to provide caves or old hollow trees. ...
Chapter
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South Africa is the World’s largest producers of macadamia nuts, with about 51,000 ha of land covered by macadamia. This leads to major farming challenges, as the expansion of orchards is associated with the loss of habitat and biodiversity, the excessive use of and resistance to insecticides, and an increased pressure on water resources. More frequent and severe droughts and heat waves are projected to worsen the situation and have already negatively affected harvests. Here we review current literature and recent work conducted in the subtropical fruit growing area of Levubu, South Africa, which include catchment-scale assessments of ground water, landscape-scale studies on pest control and pollination services, through to evaluations of tree-level water use. Several biological control options are being developed to replace pesticides. Results suggest that bats and birds provide large and financially measurable pest control services, and interventions should therefore focus on maintaining functional landscapes that would be resilient in the face of global climate change. This would include a landscape matrix that includes natural vegetation and minimize water consumption by optimizing irrigation schedules.
... Predictors such as abiotic variables (n = 26, 8.4%), presence/ number of insects (n = 12, 3.9%) and agricultural system management approaches (n = 47, 15.2%) were occasionally studied in more than one scale (Supplementary Table 3). Abiotic variables can affect bat responses to agricultural systems (Cisneros et al., 2015;Heim et al., 2016;Shapiro et al., 2020). In cultivated landscapes in the Neotropics, for example, bats may respond positively to forest patch size in the dry season and have no relationship with this variable in the wet season (Cisneros et al., 2015). ...
... In cultivated landscapes in the Neotropics, for example, bats may respond positively to forest patch size in the dry season and have no relationship with this variable in the wet season (Cisneros et al., 2015). In the Afrotropic, insectivores respond more strongly to landscape metrics in the dry season, while in the wet season they respond more strongly to local metrics (Shapiro et al., 2020). To better understand the response of bats to agricultural systems, it is important to analyse how abiotic variables interact with other factors in both the agriculture system and the surrounding landscape. ...
Article
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Introduction The conversion of natural habitats to agricultural systems is one of the main global threats to bats. Here, we aimed to develop a systematic mapping to identify publication trends and research gaps in studying bats and agricultural systems. Methods We reviewed 309 studies published between 1990 and 2021 that sampled bats in agricultural systems or evaluated the effect of these systems on these animals. Results We found that most studies were conducted in the Palearctic and Neotropical regions (55.3%) and forest biomes (66.0%). Grassland-cropland systems (50.2%) and forest plantations that do not require cutting during the extraction of their products (47.9%) were more studied than forest plantations that require cutting (19.7%). Additionally, acoustic recordings (41.1%) and mist nets (34.3%) were the primary sampling methods used, with few studies combining these methods (7.1%). Also, most studies were conducted on a local scale (77.7%). The number of landscape-scale studies was smaller (34.3%) and concentrated in the Palearctic region (39.6%). Most studies assessed how agricultural systems affect biodiversity (62.1%). However, the phylogenetic and functional dimensions and b-diversity were little explored, with 2.5% and 23.3% of the biodiversity studies, respectively. Of the proposed mitigation measures, the most cited was including natural/semi-natural/potential bat habitats in cultivated landscapes (59.5%). Discussion In summary, our findings highlight the need for attention to the Afrotropic and Indo-Malaysia regions; predominantly non-forested biomes; plantations that require cutting during the extraction of their products; combined use of different sampling methods, as well as other methods as telemetry; use of multiple biodiversity descriptors and others biological descriptors, such as ecological services; landscape-scale studies and the role of conservation policies in promoting their conservation and raising awareness of their importance among producers and local communities. Filling these knowledge gaps is necessary to understand the factors influencing bat survival in cultivated landscapes. This is the only way to develop management and conservation strategies in these landscapes.
... Some studies have investigated African bat responses to seasonal and habitat changes in dry regions [34,35], showing that bat activity declines during the dry season, and that land cover associations are guild-and season-specific. Other studies suggest that bats may also segregate their niche based on height, with traits such as diet, wing morphology, and echolocation playing key roles in determining their vertical stratification [36]. ...
... We hypothesised that due to the distinct strategies that each guild uses to exploit their prey and the way they use the vertical dimension, there is a trade-off in the variables that drive their activity. Therefore, we predicted that the activity of lowflying species is driven mainly by habitat variables (e.g., land cover, terrain, and water availability) [34]. In contrast, we predicted that the activity of higher-flying species is mainly driven by weather and other environmental variables, such as wind speed and moon phase [43]. ...
Article
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Africa faces significant challenges in balancing economic and social development while preserving its natural resources. However, we still have much to learn about the diverse bat community on the continent, especially in drier ecosystems. In our study, conducted in a semi-arid region of Kenya, we aimed to provide detailed information on what influences the number and activity of bats. We used acoustic sampling and other methods to assess bat activity at different heights above the ground. We surveyed 48 ground-level sites and two sites on meteorological masts, at 20 and 35 meters above the ground. We identified over 20 bat species, including one species of conservation concern. Our analysis showed that different variables affect bat activity. Low-flying bat species were influenced by habitat variables, while high-flying species depended more on weather conditions. Our study highlights the richness of bat populations in semi-arid environments and emphasizes the need for conservation measures. Climate change, land management, and development projects threats bat diversity and their habitats. It is crucial to implement effective management strategies to protect these species. Our findings contribute to the development of conservation efforts for bat populations in Africa and beyond.
... Vegetation provides key structural elements that are important for clutter and clutter-edge foragers as the bats forage around vegetation edges and within the natural vegetation, likely explaining the prevalence of clutter-edge foragers, especially in the dry season (Shapiro, Monadjem, Röder & McCleery, 2020). Open-air foragers search for insects above vegetation (sometimes up to several kilometres in the air) rather than along its edges . ...
... Clutter foragers had the lowest activity of the three guilds in our study. This foraging guild typically has short and broad wings, ideal for high maneuverability for foraging in dense, cluttered vegetation Shapiro et al., 2020). Clutter foragers also have short detection ranges with bat detectors (Monadjem et al., 2017). ...
... However, studies on biodiversity in sub-Saharan Africa have traditionally focused on natural ecosystems (protected areas), giving only limited attention to modified landscapes, such as agroecosystems (Nkrumah et al. 2017). Moreover, some agroecosystems have been found to serve as a refugium of tropical biodiversity (Perfecto et al. 1996;Somarriba et al. 2004;Sirami et al. 2013;Weier et al. 2018;Shapiro et al. 2020). ...
... Moreover, the presence of species that mainly exploit densely cluttered habitats, such as Hipposideros fuliginosus and H. ruber in these agricultural areas can be attributed to the fact that the vegetation structure of some agricultural areas is similar to natural cluttered habitats. A study by Shapiro et al. (2020) in savanna fragments showed the importance of sugarcane farms in providing complementary resources lacking in the monocultures, such as particular prey items or roosting sites. Indeed, we also recorded Chaerephon pumilus in cultivated farms (12 individuals). ...
Article
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The western region of Cameroon is one of the leading agricultural production areas in sub-Saharan Africa, and this ongoing anthropogenic perturbation has led to the replacement of natural forests with agroecosystems. Such anthropogenic landscape transformations may have affected bat species composition and abundance in the area. Our study assessed the response of bat assemblages to these changes, by comparing species diversity and abundance across four distinct habitat types within the region: cultivated farms (transformed landscape), savannah and gallery forest (both representing degraded areas), and secondary forest. A total of 442 individuals assigned to 25 species were captured using ground-level mist nets. The cultivated farms recorded the highest bat species richness (13 species) and abundance (145 individuals), whereas the gallery forest had the lowest species richness (six species) and abundance (62 individuals). Myonycteris angolensis had the highest relative abundance in the region, with large numbers captured in cultivated farms. According to the rank-frequency diagram, bat assemblages in cultivated farms (Akaike’s Information Criterion (AIC) = 53.7), gallery forest (AIC = 27.7), and secondary forest (AIC = 48.5) are distributed according to the pre-emption model, whereas the distribution in the savannah (AIC = 40.0) follow the null model. Generalised linear models revealed significant differences in species and relative abundance across the four habitat types.
... Water sources are well known as hotspots for bats in South Africa, supporting high species richness and high activity levels (Monadjem and Reside, 2008;Sirami, Jacobs and Cumming, 2013;Shapiro et al., 2020;Taylor et al., 2020). However, most work has been conducted in savanna habitats and agricultural landscapes, with few studies investigating the association of bats with rivers and waterbodies in forested habitats (Rautenbach, Whiting and Fenton, 1996). ...
... The association of functional diversity with river length was particularly driven by miniopterid and vespertilionid bats of the clutter-edge foraging guild that hunt for prey along riparian vegetation of watercourses (Monadjem, Taylor, et al., 2010). Similar use of rivers by the clutter-edge guild has been found for savanna habitats (Shapiro et al., 2020;Taylor et al., 2020). However, this study shows how rivers allow for the penetration of clutter-edge species into forest interiors. ...
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Bats are a highly diverse mammalian order and are some of the most economically important non-domesticated vertebrates, providing many ecosystem services that contribute to the global economy. Yet, they remain a largely understudied taxon, particularly in the Eastern Cape province of South Africa, in which basic surveys of bat assemblages utilising indigenous forests are lacking. Indigenous forests constitute South Africa’s smallest and most fragmented biome yet support disproportionally high biodiversity. They have been fragmented throughout most of their evolutionary history due to global palaeoclimatic shifts; the responses of bats to forest fragmentation and historical climatic shifts in this habitat have been poorly studied. This study addresses these gaps with the broad aims of compiling a species inventory from 17 forests across the Eastern Cape and KwaZulu-Natal provinces; assessing the effects of fragmentation and biogeography on taxonomic and functional diversity of bat assemblages; and determining how genetic diversity and population genetic structure are informed by forest habitat associations and fragmentation. A multi-faceted approach of sampling methods, including capture and acoustic recording, and species identification techniques (morphology, acoustics, and DNA barcoding) were used to assemble an inventory of 25 species, with range extensions noted for six species. The first reference call library of hand released bats for forests in this region is presented, which may be used for species identification in further acoustic surveys. A minimum acoustic monitoring period of 6 to 7 nights per forest is recommended for future surveys. Forest biogeography was an important determinant of the functional diversity of insectivorous bat assemblages. Forest edge effects were found to demonstrate a positive relationship with functional evenness, thus motivating for maintenance and conservation of forest edges, particularly in temperate regions. Larger forearm length and low wing loading were identified as morphological traits exhibiting greater sensitivity to fragmentation, flagging species exhibiting these traits as potentially vulnerable to habitat fragmentation. The effect of historical climate-induced fluctuations of forest extent on population genetic structuring and demographic histories for six species was investigated using two mitochondrial markers, cytochrome b and D-loop. Population genetic trends were not informed by forest habitat associations, but rather by species-specific traits of dispersal ability, philopatry, and roost utilisation. Low genetic diversity and high population structure identify two species, Rhinolophus swinnyi and Laephotis botswanae, for conservation priority. Demographic responses to the Last Glacial Maximum (LGM) were not detected, with all six species displaying population expansions over this time. It appears that volant insectivores in eastern South Africa were less affected by the harsh conditions of the LGM than elsewhere. The dusky pipistrelle (Pipistrellus hesperidus) was used as a model organism to investigate the gene flow, genetic diversity, and migration of a forest-utilising species across the region with the use of eight microsatellite markers. The effects of urbanisation and agricultural development on gene flow were also examined. Findings of low population structure, low migration rates, and two genetic discontinuities were presented. This species does not depict dependence on forested habitats to maintain genetic connectivity on the landscape. The data also suggest that agricultural development and urbanisation have not yet had an impact on gene flow, thus providing a baseline with which to monitor the effects of future anthropic development on this species. Overall, this study has provided novel insights into the taxonomic, functional, and genetic diversity of forest-utilising bats in relation to biogeographical history and fragmentation within eastern South Africa.
... Although data collected for ≥2 years was used in 68 % of studies (n = 118), temporal and seasonal influences on scale responses were considered by only 23 studies and focused on species from the families Vespertilionidae, Phyllostomidae, and Pteropodidae (e.g., Ferreira et al., 2017;Vardon et al., 2001;Cisneros et al., 2015;Shapiro et al., 2020). Spatially dynamic parameters with meta-replicated study areas were considered in only five studies (Pardini et al., 2009;Farneda et al., 2019;Hale et al., 2012;Starbuck et al., 2020;Bergeson et al., 2020). ...
... Schroth and Harvey 2007) that offer many feeding and shelter possibilities for wildlife (Shapiro et al. 2020 In our study area, human growth and the resulting unsustainable use of natural resources pose the biggest threat to wildlife. Three of the species that were recorded in the area are classed as nearthreatened (NT), and ve species are rated as least concern (LC) based on the IUCN Red List of Threatened Species. ...
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The purpose of this study was to assess the diversity, abundance, and major threats to large- and medium-sized mammal species in the Mbangassina Council Forest in Centre region of Cameroon. The purpose was to assist the municipality in implementing its local strategy for sustainable development. The data were collected between March 6 and April 22, 2022, using the line-transects distance sampling method and reconnaissance walks (recce). A total of 33 transects were covered, for a completion rate of 97.45% in the study area. The results of the study confirm the presence of nine species of large and medium mammals belonging to four orders, four families dominated by Artiodactyles. The large and medium-sized mammals recorded during our surveys included the black-backed duiker ( Cephalophus dorsalis ), yellow-backed duiker ( Cephalophus silvicultor ), pangolin ( Manis sp.), moustached monkey ( Cercopithecus cephus ), sitatunga ( Tragelphus spekii ), civet ( Civettictis civetta ), blue duiker ( Philantomba monticola ), and red-flanked duiker ( Cephalophus rufilatus ). The diversity index was 0.99 for a total mammal Kilometric Abundance Index (KAI) of 0.51 indices/km. However, the study area recorded a total KAI of 0.31 individuals per kilometer for 21 indices of human presence.The high value of the observed diversity index reflects the ecological importance of this ecological entity for the Municipality of Mbangassina, and the authorities must intensify their protection effort to reduce illegal activities in these areas.
... Yet, little research has focused on bat populations across seasons in urbanized environments. In addition to urbanization, habitat use of bat species is influenced by food and water availability (Korine & Pinshow, 2004;Shapiro et al., 2020;Threlfall et al., 2011) and other anthropogenic disturbances (Barré et al., 2021;Lehrer et al., 2021;Schoeman, 2016). Some bat species may select for areas with higher plant productivity and water availability, due to an increase in insect abundance and water resources, which might be especially important for bats in arid environments where water is a limiting resource during some seasons (Ancillotto et al., 2019;McCain, 2007;Mendes et al., 2017). ...
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Urbanization that occurs across a gradient from low‐ to high‐density development, is a primary driver of landscape change that can affect biodiversity. Animals balance trade‐offs in obtaining resources and avoiding anthropogenic disturbances across the gradient of urbanization to maximize their fitness. However, additional research is necessary to understand seasonal variations in how animals respond to urbanization, particularly in arid regions, where resource availability shifts drastically across seasons. Our objective was to evaluate the response of a suite of bat species to urbanization and whether species shift their response to urbanization across seasons. We predicted that the response of bats to urbanization would differ among species, with some species being more sensitive to urbanization than others. We also predicted that bat species would increase the use of moderate and highly urbanized areas in the summer season where food and water resources were assumed to be greater compared with wildland areas. To evaluate these predictions, we used a stratified random sampling design to sample 50 sites with stationary acoustic bat monitors across the gradient of urbanization in the Phoenix metropolitan area, Arizona, USA during four seasons. We identified a total of 14 bat species during 1000 survey nights. Consistent with predictions, bat species exhibited different responses to urbanization, with most species exhibiting a negative relationship with urbanization, and some species exhibiting a quadratic or positive relationship with urbanization. Counter to predictions, most species did not appear to shift their response to urbanization across seasons. Consistent with predictions, plant productivity and water were important for some species in the summer season. Differences in the response of bat species to urbanization was likely related to species traits (e.g., wing morphology and echolocation call characteristics) and behavioral strategies that influence a species' sensitivity to anthropogenic disturbances and ability to access available resources in urbanized areas. Ultimately, to promote the management and conservation of bats, it is likely important to maintain resources in urbanized areas for bats that are more tolerant of urbanization and to conserve areas of undeveloped high‐quality habitat with low anthropogenic disturbance in wildland areas for bats that are sensitive to urbanization.
... We found that when considering the abundance and richness of all guilds together results vary from the ones observed when guilds are considered separately. This is in line with other studies conducted in other areas that showed that bat responses to habitat disturbance are guild-specific (Williams-Guillén and Perfecto, 2010;Shapiro et al., 2020;Ocampo-Ariza et al., 2022). ...
... In addition to providing bats with a source of water, water bodies also aggregate insect prey, and this in turn drives spatial and temporal patterns in bat activity (Fukui et al., 2006;Grindal et al., 1999;Hagen and Sabo, 2012). We found that bat detections at water bodies are considerably higher than those at sites in the grasslands, concordant with other studies conducted during the dry season when water and other resources are scarce (Shapiro et al., 2020;Vaughan et al., 1997;Williams et al., 2006). Bats descending to drink at water bodies, or attempting to capture insects over them, are more likely to be detected by bat recorders, and bats detected in the grasslands may have been transiting to and from these water bodies. ...
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Arid and semiarid environments of the world are characterized by extreme environmental changes that affect the availability of scarce, patchily distributed resources such as water. In response to these changes, animals migrate or partition resources to minimize competition, resulting in temporal patterns within assemblages across multiple scales. Here, we demonstrate that the winter dry season bat assemblage in a semiarid grassland of northwestern India exhibits seasonal changes and temporal avoidance between coexisting species. Using a passive acoustic monitoring framework to quantify activity patterns at different points in the season, we show that members of this assemblage (Rhinolophus lepidus and Tadarida aegyptiaca) exhibit seasonal differences in activity, being more frequently detected in the early and late parts of the dry season, respectively. Other species (Pipistrellus tenuis and Scotophilus heathii) do not exhibit seasonal changes in activity, but structure diel activity patterns, minimizing temporal overlap (and thus competition) at water bodies. These data, some of the first on bats from this region, demonstrate the complex temporal patterns structuring bat assemblages in arid and semiarid biomes. Our results hold promise both in understanding bat behavioral ecology and in long-term monitoring efforts.
... We discovered that insectivorous bats have species-and guild-specific responses to different landscape features. Such responses may be influenced by their wing morphology, foraging strategy, and echolocation call characteristics [71][72][73][74][75]. Our finding that the activity of narrow-space foragers is positively correlated with the proportion of forest and seminatural area within a 1 km radius is easily explained as these bats (such as Rhinolophus spp.) have broad wings and low wing loadings, making them highly maneuverable and able to forage in cluttered vegetation [76]. ...
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The extent to which organic farming can support biodiversity has been extensively studied. However, most of the research has been conducted on organic farms in temperate regions, with the focus mainly being on birds, insects, and plants and rarely on insectivorous bats, especially in Southeast Asia. We studied pairs of matched organic and conventional rice fields along a gradient of landscape complexity in the Songkhla Lake Basin and conducted acoustic surveys using bat detectors to analyze the influence of farming system and landscape characteristics on bat activity and prey availability. We also tested the “intermediate landscape complexity” hypothesis, which states that local conservation efforts are most effective in landscapes of intermediate complexity compared to extremely simple or extremely complex landscapes. We detected no difference in bat species richness, total bat activity, feeding activity, and insect prey abundance between organic fields and conventional fields. Even though organic farming did not increase bat activity on its own, it was most beneficial to bat activity in landscapes of intermediate complexity. Our findings suggest that landscape traits contribute more to bat activity than farm management and that insectivorous bats have species- and guild-specific responses to various landscape contexts. We also found that disturbance caused by tropical storms negatively impacts the activity of insectivorous bat.
... Therefore, we investigated the prevalence of coronaviruses in bats belonging to eight species from four families (Pteropodidae: Epomophorus wahlbergi; Emballonuridae: Taphozous mauritianus; Molossidae: Chaerephon pumilus, Mops condylurus, and Mops midas; and Vespertilionidae: Afronycteris nana, Scotophilus dinganii, and Scotophilus viridis). These species are all widely distributed and abundant across southeastern Africa and are commonly found in or near human settlements in northeast Eswatini (Monadjem et al. 2020b(Monadjem et al. , 2021Shapiro et al. 2020). We subjected fecal samples to virion enrichment followed by RNA sequencing to noninvasively investigate the prevalence and types of coronavirus in the bats of this region. ...
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We investigated the prevalence of coronaviruses in 44 bats from four families in northeastern Eswatini using high-throughput sequencing of fecal samples. We found evidence of coronaviruses in 18% of the bats. We recovered full or near-full-length genomes from two bat species: Chaerephon pumilus and Afronycteris nana , as well as additional coronavirus genome fragments from C. pumilus , Epomophorus wahlbergi , Mops condylurus , and Scotophilus dinganii . All bats from which we detected coronaviruses were captured leaving buildings or near human settlements, demonstrating the importance of continued surveillance of coronaviruses in bats to better understand the prevalence, diversity, and potential risks for spillover.
... Landscape heterogeneity has been shown to have a strong influence on the distribution of mammals in agricultural mosaics Shapiro et al. 2020 ), but the response of scavengers to fragmentation and patch size is not uniform. In a cornfield-woodlot agroecosystem of the central United States, patch connectivity did not influence carcass detection ( Olson et al. 2016 ). ...
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Increased agricultural intensification and extensive woody plant encroachment are having widespread effects on the functioning of grass-dominated systems at multiple spatial scales. Yet there is little understanding of how the provisioning of biodiversity-based ecosystem services might be altered by these ongoing changes. One fundamental ecosystem service that is decreasing globally, especially in human-altered landscapes, is scavenging that regulates disease processes, alters species distributions, and influences nutrient cycling. Accordingly, our goal was to understand how facultative scavenging, particularly that of mesocarnivores, was affected by landscape heterogeneity and woody encroachment in tropical-grassy savannas within an agricultural landscape mosaic. We baited (using chicken carcasses) plots across a gradient of land cover heterogeneity in areas with an open and closed canopy and subsequently measured scavenging rates. We found that scavenging efficiency of mesocarnivores and other small vertebrates was dependent on environmental variation at multiple spatial scales within our savanna agroe-cosystem. Mesocarnivores removed more bait when the overstory canopy at the plot (i.e., exact location of bait station) was more closed; in contrast, mesocarnivore scavenging was less efficient when patches (50 × 50 m area around the bait station) within the site had a higher density of shrubs. At the landscape scale, increased land cover fragmentation resulted in decreased amounts of scavenging by mesocarni-vores. This study demonstrates that a relatively transformed agroecosystem can support the provision of important ecosystem services and offer an important buffer against loss of ecosystem services. Our results suggest that targeted woody encroachment control, protection of large trees, and management or mitigation of extreme levels of fragmentation can help maintain ecosystem service provision and biodiversity .
... We captured bats using 12 m x 3 m mist nets (EcoTone, Poland) placed around suspected roosts and areas of likely bat activity, such as water bodies or pathways (Shapiro et al. 2020). We set mist nets before sunset (before bat emergence) and kept them open for four hours, during which time we checked nets at least every 10 minutes. ...
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Behavior and personality play a crucial role in the evolution and ecology of animal species. We have limited knowledge of bat personality traits, partially due to the time, equipment, and facilities needed to measure them. To help fill this gap, we developed a scale for quantifying aggressiveness in bats that can be used during ordinary fieldwork and handling by researchers. This scale is based on observations of the following ecologically relevant and easily observed behaviors in wild-captured bats during routine handling: amount and intensity of physical struggling, teeth-baring, and biting. We then applied this scale to 35 wild-caught individual bats belonging to three different species or species groups (Chaerephon pumilus, n=29; Scotophilus dinganii, n=3; and pipistrelloid bats, n=3) and measured agreement between observers using intraclass correlation coefficients (ICCs). We found that agreement between observers was good to excellent. This scale of aggressiveness provides an important, practical tool for researchers to reliably quantify this personality trait in wild bats that requires no additional equipment and minimal additional handling time. Collecting data on aggressive behavior during handling has the potential to increase our understanding of both intra-and interspecific variation in aggressiveness in bats, as well as the influence of this trait on many aspects of bat ecology. Finally, collecting data using this scale can facilitate comparisons between studies and promote research at broader spatial and temporal scales than commonly used in behavioral ecology studies.
... A small increase in bird abundance was noticed when the use of herbicide was simulated to be restricted to the vine rows (in the equilibrium scenario). Schaub et al. (2010), Arlettaz et al. (2012) and Paiola et al. (2020) provided evidence that patches of grassy habitats are important for the birds that feed on seeds and soil invertebrates and even for some bat species (Wickramasinghe et al., 2003;Shapiro et al., 2020). The simulation of "sustainable management" (eco-friendly scenario) substantially increased bird abundance, possibly mimicking the associated resources to more diverse and complex LULC Kirk and Lindsay, 2017;Steel et al., 2017). ...
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Sustainable management of biodiversity in agricultural landscapes is a European Union objective supported on multifunctional agri-environment measures. The effectiveness of specific practices implemented to reverse declines in farmland biodiversity should be monitored using straightforward methodologies and indicators. This work outlines an innovative hybrid framework to predict the response of biodiversity indicators to farm management options. We exemplify the framework application, integrating monitoring, statistics and spatio-temporal modelling procedures with a case study using flying vertebrates' patterns for indicating biodiversity trends. The indicators considered depict significant divergences within contrasting on-farm implemented environmental management options. In fact, while birds' abundance was expected to increase within environmentally friendly options, bats passes showed fluctuating patterns. Overall, the framework and indicators selected were considered relevant for biodiversity assessments in vineyard landscapes. This approach also provides a promising baseline to support sustainable management practices and options for other agroecosystems, derived from ecological models with increased predictive power and intuitiveness to decision makers and environmental managers.
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The Indian Flying Fox Pteropus medius , largest of the four fruit bat species in Nepal and is extensively distributed in South Asia. Their known roosts are distributed within an elevation range of 75 to 1,322 m asl east to west in the Tarai, Chure, Inner-Tarai and central Middle Mountains regions of the country. In Nepal, the species is known to pollinate and disperse seeds of more than 26 families of flowering plants. Most of the known roosts lie within and in the close vicinity of urban land and agricultural areas. Recently, impacts of global warming on roosting and foraging habitats of fruit bats including flying foxes have been evidenced in different parts of the globe, however, it is still unknown in Nepal. In addition, most of the known roosting colonies of P. medius are outside the protected areas and are vulnerable due to greater threats. To assess habitat suitability, we deployed Maximum Entropy modelling using 44 geo-referenced roosts occurrence coordinates of P. medius and 11 bio-climatic variables and land use land cover data layer with low inter-correlation (r > 0.75). The current potential distribution of the species covers an area of 16,642 Km ² (about 11.3% of the country’s total area). The most influencing predictors for the habitat suitability are identified as; urban land, water source and Annual Mean Temperature. Our model projects that the majority (99%) of the current distribution range for P. medius will remain suitable in the future, although it will expand within the lower elevations in the Tarai, Chure and Inner-Tarai regions. A shift towards northern latitude and higher elevations is not anticipated. It is imperative to record and model foraging sites occurrence to better predict the flying fox distribution in the future. Since the roosting colonies are within the settlements and farmlands, our finding can be utilized for regular surveillance and monitoring of the roosting colonies from the health perspective. Conservation efforts should focus on conservation of water source, plantation of tall and broad canopy trees and regular monitoring of roosting sites to safeguard existing roosts of the species with the prevalence of the global warming.
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Land-use change poses a significant threat to biodiversity, particularly in insular ecosystems where species exhibit higher levels of specialisation. Despite the importance of tropical islands for biodiversity conservation, the impacts of land-use change on the diel activity of insular species remain poorly understood. We addressed this gap by investigating the diel activity patterns of insectivorous bats in response to land-use change in São Tomé Island, Central West Africa. Using passive acoustic detectors, we surveyed insectivorous bats across forests, shaded plantations, oil palm plantations, agricultural and urban areas. We examined (1) how intraspecific diel activity varies between forest and human-altered land-use types, and (2) how interspecific diel activity varies within the same land-use type, by quantifying overlap coefficients in species activity. Based on 19,383 bat passes from four species, we found that the degree of overlap in species-specific activity between forests and human-altered land-use types varied between species, with the least overlap being observed between forests and urban areas for Miniopterus newtoni , and between forests and oil palm plantations for Chaerephon spp.. Overlap in the activity of different species was lower within less or not disturbed land-use types (forests and shaded plantations), where more species were present. Overall, diel activity of insectivorous bats altered according to the magnitude of structural land-use change. Such bat responses might be eventually due to the different temporal prey availability and interspecific competition in the altered land-use types. These findings comprise baseline knowledge informing evidence-based management actions across tropical island systems.
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Pteropus medius is exclusively distributed in South Asia. Among four species of fruit bats occurring in Nepal, the Indian Flying Fox is the largest of all. Their known roosts are distributed within an elevation range of 75 to 1,322 m asl throughout east west in the Tarai, Chure and Inner-Tarai region and in central Middle Mountains of the country. The species is known to pollinate and disperse seeds of more than 26 families of flowering plants. Most of the known roosts lie within and in the close vicinity of human settlements and farmlands. Recently, impacts of global warming on roost and foraging habitat of fruit bats including flying foxes have been evidenced in different parts of the globe, however, it is still unknown in Nepal. In addition, most of the known roosting colonies of P. medius are outside the protected areas and are vulnerable due to greater threats. Based upon 44 roosts occurrence coordinates of P. medius and six low-correlated bio-climatic variables (r > 0.75), we built habitat suitability models using Maximum Entropy. The current potential distribution of the species covers an area of 38,688 km ² (About 26% of the country’s total area). Minimum Temperature of Coldest Month (bio 6), Precipitation of Coldest Quarter (bio 19) and Mean Diurnal Range (bio 2) are most influencing predictors. In the future, its overall distribution range in overall will slightly contract, although it will expand at the lower elevations in Tarai, Chure and Inner-Tarai regions. The future distribution is not expected to shift towards northern latitude and higher elevations.
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Bangladesh is at the ecological transition between the Indo-Himalayan and Indo-Chinese subregions. The country also has one of the highest human population densities in the world and only 6% remaining natural habitat, putting much of its biodiversity at risk. With more than 1455 species worldwide, bats are an important, but threatened, component of global biodiversity and provide critical ecosystem services. Yet, there is no comprehensive work on species occurrence, diversity, or richness of bats of Bangladesh. Here, we collated data on the bats of Bangladesh and states in neighboring countries from the available literature, the Global Biodiversity Information Facility, and museum databases to assess the probability of occurrence of bat species in Bangladesh and created distribution maps for each species. We confirmed 31 species from 8 families, of which 22 were associated with voucher specimens and 9 recorded based on photographs, or human observation. A further 81 species were categorized as Highly Probable (38 species), Probable (33), and Possible (10) in Bangladesh based on the distribution in neighboring states and habitat preferences. The shortfall in confirmed versus potential species highlights the need for rigorous surveys to fully document and characterize the bat diversity of Bangladesh.
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Land‐cover and land‐use change are major drivers of global biodiversity loss. Savannas are experiencing shrub encroachment and land‐use changes that affect animal communities, yet how the effects of shrub encroachment vary with land use remains unclear. We also need to determine which species traits explain the effects of shrub encroachment and land‐use changes to identify potential drivers of community change and predict species' responses to conservation efforts. We sampled birds across gradients of shrub encroachment and land use (protected savanna, pastures, homestead lands, and sugarcane) in the lowveld savanna of Eswatini to: (1) test for the effects of shrub encroachment, land‐use change, and their potential synergies on the occurrence of 48 species of birds; and (2) determine which species traits (those associated with nesting, foraging, or vulnerability to predation) explained species' associations with shrub encroachment and land‐use change. We used Bayesian multispecies occupancy models to account for imperfect detection, interpret species responses, and understand the effects of species traits. We found evidence for community‐wide synergies between shrub encroachment and land‐use effects on birds that varied with species' diets. Agricultural intensification had negative effects on the occurrence of most species examined, while shrub cover typically had positive effects which were stronger in pastures and homestead lands than in protected areas. The negative effects of land‐use change were greatest for insectivores and cavity nesters, whereas insectivore occurrence increased with shrub cover, collectively indicating that nesting and foraging traits best explained species responses to land‐use and land‐cover change in the region. Our results suggest that shrub cover management for bird conservation should vary with land use: shrubs could be thinned in protected areas without reducing bird occupancy but shrubs in homesteads should be retained.
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The Okavango River Basin is a hotspot of bat diversity that requires urgent and adequate protection. To advise future conservation strategies, we investigated the relative importance of a range of potential environmental drivers of bat species richness and functional community composition in the Okavango River Basin. During annual canoe transects along the major rivers, originating in the central Angolan highlands, we recorded more than 25,000 bat echolocation calls from 2015 to 2018. We corrected for possible biases in sampling design and effort. Firstly, we conducted rarefaction analyses of each survey year and sampling appeared to be complete, apart from 2016. Secondly, we used total activity as a measure of sample effort in mixed models of species richness. Species richness was highest in the Angola Miombo Woodlands and at lower elevations, with higher minimum temperatures. In total, we identified 31 individual bat species. We show that even when acoustic surveys are conducted in remote areas and over multiple years, it is possible to correct for biases and obtain representative richness estimates. Changes in habitat heterogeneity will have detrimental effects on the high richness reported here and human land-use change, specifically agriculture, must be mediated in a system such as the Angolan Miombo Woodland.
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Human alteration of the planet’s terrestrial landscapes for agriculture, habitation and commerce is reshaping wildlife communities. The threat of land cover change to wildlife is pronounced in regions with rapidly growing human populations. We investigated how species richness and species-specific occurrence of bats changed as a function of land cover and canopy (tree) cover across a rapidly changing region of Florida, USA. Contrary to our predictions, we found negligible effects of agriculture and urban development on the occurrence of all species. In contrast, we found that a remotely sensed metric of canopy cover on a broad scale (25 km ² ) was a good predictor of the occurrence of eight out of ten species. The occurrence of all smaller bats (vespertilionids) in our study increased with 0–50% increases in canopy cover, while larger bats showed different patterns. Occurrence of Brazilian free-tailed bats ( Tadarida brasiliensis ) decreased with increasing canopy cover, and Florida bonneted bats ( Eumops floridanus ) were not influenced by canopy cover. We conclude that remotely sensed measures of canopy cover can provide a more reliable predictor of bat species richness than land-cover types, and efforts to prevent the loss of bat diversity should consider maintaining canopy cover across mosaic landscapes with diverse land-cover types.
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Bats play important ecological roles in tropical systems, yet how these communities are structured is still poorly understood. Our study explores the structure of African bat communities using morphological characters to define the morphospace occupied by these bats and stable isotope analysis to define their dietary niche breadth. We compared two communities, one in rainforest (Liberia) and one in savannah (South Africa), and asked whether the greater richness in the rainforest was due to more species 'packing' into the same morphospace and trophic space than bats from the savannah, or some other arrangement. In the rainforest, bats occupied a larger area in morphospace and species packing was higher than in the savannah; although this difference disappeared when comparing insectivorous bats only. There were also differences in morphospace occupied by different foraging groups (aerial, edge, clutter and fruitbat). Stable isotope analysis revealed that the range of δ¹³C values was almost double in rainforest than in savannah indicating a greater range of utilization of basal C3 and C4 resources in the former site, covering primary productivity from both these sources. The ranges in δ¹⁵N, however, were similar between the two habitats suggesting a similar number of trophic levels. Niche breadth, as defined by either standard ellipse area or convex hull, was greater for the bat community in rainforest than in savannah, with all four foraging groups having larger niche breadths in the former than the latter. The higher inter-species morphospace and niche breadth in forest bats suggest that species packing is not necessarily competitive. By employing morphometrics and stable isotope analysis, we have shown that the rainforest bat community packs more species in morphospace and uses a larger niche breadth than the one in savannah.
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Agricultural landscapes are typically associated with a decreased biodiversity, particularly when they extend across large spatial scales. Despite the fact that some African bat species seem to provide essential ecosystem services across landscapes, we only have a limited understanding of how intensive agricultural practices influence bat communities. This study investigated the effects of sugarcane monoculture on the composition of both bat species and functional groups across a conservation-agricultural matrix. Specifically, we wanted to understand changes in the bat communities within savannas and sugarcane plantations. We categorised bats into broad foraging (functional) groups based on their echolocation call structure: open-air; clutter-edge; and, clutter. To measure bat activity, we established twelve 25 ha grids randomly located in savanna and sugarcane vegetation. Within each grid we placed nine acoustic detectors, in 3 × 3 formation, 250 m apart; totalling 54 plots in each land use. We sampled each plot over four nights (two in the wet season and two in the dry season) during a one-year period. We did not observe a significant difference in species richness between savanna and sugarcane. However, there was a difference in functional group composition. Sugarcane negatively affected clutter foragers; this group was practically absent here despite occurring within neighbouring savannas. We observed distinct patterns of seasonality in bat activity, with activity of all functional groups being reduced in the dry season.
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Human-dominated landscapes comprise the bulk of the world’s terrestrial surface and Africa is predicted to experience the largest relative increase over the next century. A multi-scale approach is required to identify processes that maintain diversity in these landscapes. Here we identify scales at which animal diversity responds by partitioning regional diversity in a rural African agro-ecosystem between one temporal and four spatial scales. Human land use practices are the main driver of diversity in all seven animal assemblages considered, with medium sized mammals and birds most affected. Even the least affected taxa, bats and non-volant small mammals (rodents), responded with increased abundance in settlements and agricultural sites respectively. Regional turnover was important to invertebrate taxa and their response to human land use was intermediate between that of the vertebrate extremes. Local scale (< 300 m) heterogeneity was the next most important level for all taxa, highlighting the importance of fine scale processes for the maintenance of biodiversity. Identifying the triggers of these changes within the context of functional landscapes would provide the context for the long-term sustainability of these rapidly changing landscapes.
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The bat fauna of arid regions is still poorly studied mostly due to a lack of interest in areas with low species richness and a low number of threatened species. In this study, we reviewed the status of bat diversity in the arid parts of southern Africa, with the aim of setting up a baseline for future work. In particular, we described species richness patterns across four arid zones within the region (Namib Desert, Kalahari, Nama Karoo and Succulent Karoo), exploring abiotic gradients and local landscape structure. Additionally, we examined bat functional groups in this region and compared them with those of three other arid regions of the world to identify potential similarities and differences. The southern African arid region hosted 17 bat species, representing eight families, of which three are endemic to the region (Rhinolophus denti, Laephotis namibensis and Cistugo seabrae) and one is vagrant (the fruit bat Eidolon helvum). Species richness varied spatially within this arid region, being highest in the drier but topographically heterogeneous Namib Desert, probably as a result of roost availability. With regards to functional groups, the southern African arid region had few bat species adapted to foraging in open spaces, particularly when compared with the neighbouring savannahs. Drawing from this study, we suggest that: a) despite species richness decreasing with increasing aridity at the sub-continental scale, at a more local scale landscape features (e.g. habitat structure) might be more relevant than aridity in determining bat species richness; and b) an unknown factor, possibly patterns of temperature limiting the availability of insects flying high above the ground, restricted the diversity of the open air foragers throughout the region. We highlight additional areas of research worth investigation.
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The Brazilian Cerrado is a Neotropical savanna extremely threatened by human-driven habitat changes while simultaneously one of the formations with the highest degree of floristic endemism in the world. In the last decades, more than half of the Cerrado area has been converted by agriculture and livestock production, leading to a significant loss of its natural vegetation. Here we evaluated changes in bat diversity between varying agricultural land use intensity levels and phytophysiognomies of the Cerrado. Because processes behind the patterns of community assembly act on ecological redundancies and complementarities of organisms and not only, or necessarily, on the number of species present in a certain region, we focused on taxonomic, functional and phylogenetic diversity of bats. We predicted that all three dimensions of bat diversity were negatively correlated with increasing levels of land-use intensity in the Cerrado, and that this pattern was mirrored in distinct phytophysiognomies of the domain. We sampled bats in the central Brazilian Cerrado using a comprehensive sampling scheme of mist-nets and automated real-time ultrasound-recording units in 27 sampling points covering different physiognomies and levels of land-use modification for two consecutive years. To our knowledge our sampling was unique in combining these two techniques, returning information on close-, edge- and open-space foraging guilds, rarely all sampled in Neotropical bat studies. A remarkable total of 64 species of six families were registered in the study area. In general no statistical differences were found in any of the diversity metrics between the sampled physiognomies, but a decrease in taxonomic, functional and phylogenetic diversity was observed in all physiognomies associated with land use intensification and this was consistent across guilds. This demonstrates the potential negative impact of land use intensification in ecosystem services provided by bats, including pollination, seed dispersal and insect control.
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Accurate taxonomy is central to the study of biological diversity, as it provides the needed evolutionary framework for taxon sampling and interpreting results. While the number of recognized species in the class Mammalia has increased through time, tabulation of those increases has relied on the sporadic release of revisionary compendia like the Mammal Species of the World (MSW) series. Here, we present the Mammal Diversity Database (MDD), a digital, publically accessible, and updateable list of all mammalian species, now available online: https://mammaldiversity.org. The MDD will continue to be updated as manuscripts describing new species and higher taxonomic changes are released. Starting from the baseline of the 3rd edition of MSW (MSW3), we performed a review of taxonomic changes published since 2004 and digitally linked species names to their original descriptions and subsequent revisionary articles in an interactive, hierarchical database. We found 6,495 species of currently recognized mammals (96 recently extinct, 6,399 extant), compared to 5,416 in MSW3 (75 extinct, 5,341 extant)—an increase of 1,079 species in about 13 years, including 11 species newly described as having gone extinct in the last 500 years. We tabulate 1,251 new species recognitions, at least 172 unions, and multiple major, higher-level changes, including an additional 88 genera (1,314 now, compared to 1,226 in MSW3) and 14 newly recognized families (167 compared to 153). Analyses of the description of new species through time and across biogeographic regions show a long-term global rate of ~25 species recognized per year, with the Neotropics as the overall most species-dense biogeographic region for mammals, followed closely by the Afrotropics. The MDD provides the mammalogical community with an updateable online database of taxonomic changes, joining digital efforts already established for amphibians (AmphibiaWeb, AMNH’s Amphibian Species of the World), birds (e.g., Avibase, IOC World Bird List, HBW Alive), non-avian reptiles (The Reptile Database), and sh (e.g., FishBase, Catalog of Fishes).
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Context The landscape heterogeneity hypothesis states that increased heterogeneity in agricultural landscapes will promote biodiversity. However, this hypothesis does not detail which components of landscape heterogeneity (compositional or configurational) most affect biodiversity and how these compare to the effects of surrounding agricultural land-use. Objectives Our objectives were to: (1) assess the influence of the components of structural landscape heterogeneity on taxonomic diversity; and (2) compare the effects of landscape heterogeneity to those of different types of agricultural land-use in the same landscape across different taxonomic groups. Methods We identified a priori independent gradients of compositional and configurational landscape heterogeneity within an agricultural mosaic of north-eastern Swaziland. We tested how bird, dung beetle, ant and meso-carnivore richness and diversity responded to compositional and configurational heterogeneity and agricultural land-use across five different spatial scales. Results Compositional heterogeneity best explained species richness in each taxonomic group. Bird and ant richness were both positively correlated with compositional heterogeneity, whilst dung beetle richness was negatively correlated. Commercial agriculture positively influenced bird species richness and ant diversity, but had a negative influence on dung beetle richness. There was no effect of either component of heterogeneity on the combined taxonomic diversity or richness at any spatial scale. Conclusions Our results suggest that increasing landscape compositional heterogeneity and limiting the negative effects of intensive commercial agriculture will foster diversity across a greater number of taxonomic groups in agricultural mosaics. This will require the implementation of different strategies across landscapes to balance the contrasting influences of compositional heterogeneity and land-use. Strategies that couple large patches of core habitat across broader scales with landscape structural heterogeneity at finer scales could best benefit biodiversity.
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Understanding the distributions and environmental associations of rare species is a critical 1st step in their conservation and management. Federally endangered Florida bonneted bats (Eumops floridanus) are endemic to southern Florida and are believed to have one of the most limited geographic distributions of any bat in the United States. We conducted a large-scale acoustic survey of 330 points spread across approximately 38,000 km 2 over a 2-year period and used a hierarchical Bayesian approach accounting for imperfect detection to model the distribution and environmental associations of the Florida bonneted bat. Bat occupancy was negatively correlated with the amount of developed land within 5 km of the sampling point and positively correlated with the amount of crop-based agriculture within 5 km of the sampling point. Bat occupancy probabilities increased with the 30-year mean for minimum spring temperature and levels of annual precipitation, and decreased with the 30-year mean for levels of spring precipitation. Bat detection was positively influenced by Julian date and minimum temperature of the survey night. This study offers new insight into the habitat use of this endangered species. Results confirm that predicted changes in land cover and climate will be threats to the Florida bonneted bat.
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Bats are a critical component of most terrestrial systems, yet accurately assessing species richness and abundances remains a challenge. The use of acoustic monitoring has increasingly been used to assess bat communities. Compared with more traditional trapping surveys, acoustic monitoring is relatively easy to use and vastly increases the amount of data collected. However, the ability to accurately identify bat calls from acoustic detectors is limited by the availability of regional call libraries describing the calls of local species. Further, the lack of knowledge of detection distances for different species limits the ability to compare activity levels or abundances between species. We developed an echolocation call library based on zero-crossing recordings with Anabat Express detectors that can be applied broadly to bat acoustic detector surveys across the savanna systems of Swaziland and South Africa, and potentially the broader region of Southern Africa. We also compared detection distances for different species and provide a correction factor that will increase our ability to accurately compare activity between different species.
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Seasonality causes fluctuations in resource availability, affecting the presence and abundance of animal species. The impacts of these oscillations on wildlife populations can be exacerbated by habitat fragmentation. We assessed differences in bat species abundance between the wet and dry season in a fragmented landscape in the Central Amazon characterized by primary forest fragments embedded in a secondary forest matrix. We also evaluated whether the relative importance of local vegetation structure versus landscape characteristics (composition and configuration) in shaping bat abundance patterns varied between seasons. Our working hypotheses were that abundance responses are species as well as season specific, and that in the wet season , local vegetation structure is a stronger determinant of bat abundance than landscape-scale attributes. Generalized linear mixed-effects models in combination with hierarchical partitioning revealed that relationships between species abundances and local vegetation structure and landscape characteristics were both season specific and scale dependent. Overall, landscape characteristics were more important than local vegetation characteristics, suggesting that landscape structure is likely to play an even more important role in landscapes with higher fragment-matrix contrast. Responses varied between frugivores and animalivores. In the dry season, frugivores responded more to compositional metrics, whereas during the wet season, local and configurational metrics were more important. Animalivores showed similar patterns in both seasons, responding to the same group of metrics in both seasons. Differences in responses likely reflect seasonal differences in the phenology of flowering and fruiting between primary and secondary forests, which affected the foraging behavior and habitat use of bats. Management actions should encompass multiscale approaches to account for the idiosyncratic responses of species to seasonal variation in resource abundance and consequently to local and landscape scale attributes. K E Y W O R D S Chiroptera, fragmentation, landscape structure, local vegetation structure, seasonality
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The coefficient of determination, a.k.a. R², is well-defined in linear regression models, and measures the proportion of variation in the dependent variable explained by the predictors included in the model. To extend it for generalized linear models, we use the variance function to define the total variation of the dependent variable, as well as the remaining variation of the dependent variable after modeling the predictive effects of the independent variables. Unlike other definitions which demand complete specification of the likelihood function, our definition of R² only needs to know the mean and variance functions, so applicable to more general quasi-models. It is consistent with the classical measure of uncertainty using variance, and reduces to the classical definition of the coefficient of determination when linear regression models are considered.
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ContextSpecies site-occupancy patterns may be influenced by habitat variables at both local and landscape scales. Although local habitat variables influence whether the site is suitable for a given species, the broader landscape context can also influence site occupancy, particularly for species that are sensitive to land-use change. Objectives To examine the relative importance of local versus landscape variables in explaining site occupancy of eight bat species within the Brazilian Cerrado, a Neotropical savanna that is experiencing widespread habitat loss and fragmentation. Methods Bats were surveyed within 16 forest patches over two years. We used a multi-model information-theoretic approach, adjusted for species detection bias, to assess whether landscape variables (percent cover and number of patches of natural vegetation within a 2- and 8-km radius of each forest site) or local site variables (canopy cover, understory height, number of trees, and number of lianas) best explained site occupancy in each species. ResultsLandscape variables were among the best models (ΔAICc or ΔQAICc < 2) for four species (top-ranked model for black myotis), whereas local variables were among the best for five species (top-ranked model for vampire bats). Neither local nor landscape variables explained site occupancy in two frugivorous species. Conclusion Species associated with a particular habitat type will not respond similarly to the amount, distribution or relative suitability of that habitat, or even at the same scale. This reinforces the challenge of species distribution modelling, especially in the context of forecasting species’ responses to future land-use or climate-change scenarios.
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ContextThe conversion of natural environments into agricultural land has profound effects on the composition of the landscape, often resulting in a mosaic of human-altered and natural habitats. The response to these changes may however vary among organisms. Bats are highly vagile, and their requirements often imply the use of distinct habitats, which they select responding to both landscape and local features. Objectives We aimed to identify which features influence bat richness and activity within Baixo Vouga Lagunar, a heterogeneous landscape located on the Central-North Portuguese coast, and to investigate if that influence varies across a gradient of focal scales. Methods We sampled bats acoustically, while simultaneously sampling insects with light traps. We assessed the relationships between species richness, bat activity, and activity of eco-morphological guilds with landscape and local features, across four scales. ResultsOur results revealed both scale- and guild-dependent responses of bats to landscape and local features. At broader scales we found positive associations between open-space foraging bats and habitat heterogeneity and between edge-space foraging bats and greater edge lengths. Woodland cover and water availability at an intermediate scale and weather conditions and insect abundance at a local scale were the factors that mostly influenced the response variables. Conclusions Globally, our results suggest that bats are sensitive to local resource availability and distribution, while simultaneously reacting to landscape features acting at coarser scales. Finally, our results suggest that the responses given by bats are guild-dependent, and some habitats act as keystone structures for bats within this mosaic.
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For decades, there has been enormous scientific interest in tropical savannahs and grasslands, fuelled by the recognition that they are a dynamic and potentially unstable biome, requiring periodic disturbance for their maintenance. However, that scientific interest has not translated into widespread appreciation of, and concern about threats to, their biodiversity. In terms of biodiversity, grassy biomes are considered poor cousins of the other dominant biome of the tropics—forests. Simple notions of grassy biomes being species-poor cannot be supported; for some key taxa, such as vascular plants, this may be valid, but for others it is not. Here, we use an analysis of existing data to demonstrate that high-rainfall tropical grassy biomes (TGBs) have vertebrate species richness comparable with that of forests, despite having lower plant diversity. The Neotropics stand out in terms of both overall vertebrate species richness and number of range-restricted vertebrate species in TGBs. Given high rates of land-cover conversion in Neotropical grassy biomes, they should be a high priority for conservation and greater inclusion in protected areas. Fire needs to be actively maintained in these systems, and in many cases re-introduced after decades of inappropriate fire exclusion. The relative intactness of TGBs in Africa and Australia make them the least vulnerable to biodiversity loss in the immediate future. We argue that, like forests, TGBs should be recognized as a critical—but increasingly threatened—store of global biodiversity. This article is part of the themed issue ‘Tropical grassy biomes: linking ecology, human use and conservation’.
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Human pressures on the environment are changing spatially and temporally, with profound implications for the planet's biodiversity and human economies. Here we use recently available data on infrastructure, land cover and human access into natural areas to construct a globally standardized measure of the cumulative human footprint on the terrestrial environment at 1 km(2) resolution from 1993 to 2009. We note that while the human population has increased by 23% and the world economy has grown 153%, the human footprint has increased by just 9%. Still, 75% the planet's land surface is experiencing measurable human pressures. Moreover, pressures are perversely intense, widespread and rapidly intensifying in places with high biodiversity. Encouragingly, we discover decreases in environmental pressures in the wealthiest countries and those with strong control of corruption. Clearly the human footprint on Earth is changing, yet there are still opportunities for conservation gains.
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Species distribution models were used to predict bat species richness across southern Africa and to identify potential drivers of these spatial patterns. We also identified species richness within each biotic zone and the distributions of species considered of high conservation priority. We used this information to highlight conservation priorities for bats in southern Africa (defined here as between the latitudes of 8° S, slightly north of Zambia, to the southern tip of Africa 34° S, an area of approximately 9781840 km 2). We used maximum entropy modelling (Maxent) to model habitat suitability for 58 bat species in order to determine the key eco-geographical variables influencing their distributions. The potential distribution of each bat species was affected by different eco-geographic variables but in general, water availability (both temporary and permanent), seasonal precipitation, vegetation, and karst (caves/limestone) areas were the most important factors. The highest levels of species richness were found mainly in the eastern dry savanna area and some areas of wet savanna. Of the species considered to be of high priority due to a combination of restricted distributions or niches and/or endemism (7 fruit bats, 23 cave-dwellers, 18 endemic and near-endemic, 14 niche-restricted and 15 range-restricted), nine species were considered to be at most risk. We found that range-restricted species were commonly found in areas with low species richness; therefore, conservation decisions need to take into account not only species richness but also species considered to be particularly vulnerable across the biogeographical area of interest.
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Model-based global projections of future land use and land cover (LULC) change are frequently used in environmental assessments to study the impact of LULC change on environmental services and to provide decision support for policy. These projections are characterized by a high uncertainty in terms of quantity and allocation of projected changes, which can severely impact the results of environmental assessments. In this study, we identify hotspots of uncertainty, based on 43 simulations from 11 global-scale LULC change models representing a wide range of assumptions of future biophysical and socio-economic conditions. We attribute components of uncertainty to input data, model structure, scenario storyline and a residual term, based on a regression analysis and analysis of variance. From this diverse set of models and scenarios we find that the uncertainty varies, depending on the region and the LULC type under consideration. Hotspots of uncertainty appear mainly at the edges of globally important biomes (e.g. boreal and tropical forests). Our results indicate that an important source of uncertainty in forest and pasture areas originates from different input data applied in the models. Cropland, in contrast, is more consistent among the starting conditions, while variation in the projections gradually increases over time due to diverse scenario assumptions and different modeling approaches. Comparisons at the grid cell level indicate that disagreement is mainly related to LULC type definitions and the individual model allocation schemes. We conclude that improving the quality and consistency of observational data utilized in the modeling process as well as improving the allocation mechanisms of LULC change models remain important challenges. Current LULC representation in environmental assessments might miss the uncertainty arising from the diversity of LULC change modeling approaches and many studies ignore the uncertainty in LULC projections in assessments of LULC change impacts on climate, water resources or biodiversity. This article is protected by copyright. All rights reserved.
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Context Scale dependence of bat habitat selection is poorly known with few studies evaluating relationships among landscape metrics such as class versus landscape, or metrics that measure composition or configuration. This knowledge can inform conservation approaches to mitigate habitat loss and fragmentation. Objectives We evaluated scale dependence of habitat associations and scaling patterns of landscape metrics in relation to bat occurrence or capture rate in forests of southwestern Nicaragua. Methods We captured 1537 bats at 35 locations and measured landscape and class metrics across 10 spatial scales (100–1000 m) surrounding capture locations. We conducted univariate scaling across the 10 scales and identified scales and variables most related to bat occurrence or capture rate. Results Edge and patch density, at both landscape and class levels, were the most important variables across species. Feeding guilds varied in their response to metrics. Certain landscape and configuration metrics were most influential at fine (100 m) and/or broad (1000 m) spatial scales while most class and composition metrics were influential at intermediate scales. Conclusions These results provide insight into the scale dependence of habitat associations of bat species and the influence of fine and broad scales on habitat associations. The effects of scale, examined in our study and others from fine (100 m) to broad (5 km) indicate habitat relationships for bats may be more informative at larger scales. Our results suggest there could be general differences in scale relationships for different groups of landscape metrics, which deserves further evaluation in other taxonomic groups.
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Land-use change is a key driver of the global biodiversity crisis and a particularly serious threat to tropical biodiversity. Throughout the tropics, the staggering pace of deforestation, logging, and conversion of forested habitat to other land uses has created highly fragmented landscapes that are increasingly dominated by human-modified habitats and degraded forests. In this chapter, we review the responses of tropical bats to a range of land-use change scenarios, focusing on the effects of habitat fragmentation , logging , and conversion of tropical forest to various forms of agricultural production. Recent landscape-scale studies have considerably advanced our understanding of how tropical bats respond to habitat fragmentation and disturbance at the population, ensemble, and assemblage level. This research emphasizes that responses of bats are often species and ensemble specific, sensitive to spatial scale , and strongly molded by the characteristics of the prevailing landscape matrix . Nonetheless, substantial knowledge gaps exist concerning other types of response by bats. Few studies have assessed responses at the genetic , behavioral , or physiological level, with regard to disease prevalence , or the extent to which human disturbance erodes the capacity of tropical bats to provide key ecosystem services . A strong geographic bias, with Asia and, most notably, Africa, being strongly understudied, precludes a comprehensive understanding of the effects of fragmentation and disturbance on tropical bats. We strongly encourage increased research in the Paleotropics and emphasize the need for long-term studies , approaches designed to integrate multiple scales, and answering questions that are key to conserving tropical bats in an era of environmental change and dominance of modified habitats (i.e., the Anthropocene).
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Natural bodies of open water in desert landscapes, such as springs and ephemeral pools, and the plant-life they support, are important resources for the survival of animals in hyper arid, arid and semi-arid (dryland) environments. Human-made artificial water sources, i.e. waste-water treatment ponds, catchments and reservoirs, have become equally important for wildlife in those areas. Bodies of open water are used by bats either for drinking and/or as sites over which to forage for aquatic emergent insects. Due to the scarcity of available water for replenishing water losses during roosting and flight, open bodies of water of many shapes and sizes may well be a key resource influencing the survival, activity, resource use and the distribution of insectivorous bats . In this chapter, we review the current knowledge of bats living in semi- and arid regions around the world and discuss the factors that influence their richness , behaviour and activity around bodies of water. We further present how increased anthropogenic changes in hydrology and water availability may influence the distribution of species of bats in desert environments and offer directions for future research on basic and applied aspects on bats and the water they use in these environments.
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An analysis of observed trends in African annual-average near-surface temperatures over the last five decades reveals drastic increases, particularly over parts of the subtropics and central tropical Africa. Over these regions, temperatures have been rising at more than twice the global rate of temperature increase. An ensemble of high-resolution downscalings, obtained using a single regional climate model forced with the sea-surface temperatures and sea-ice fields of an ensemble of global circulation model (GCM) simulations, is shown to realistically represent the relatively strong temperature increases observed in subtropical southern and northern Africa. The amplitudes of warming are generally underestimated, however. Further warming is projected to occur during the 21st century, with plausible increases of 4–6 °C over the subtropics and 3–5 °C over the tropics by the end of the century relative to present-day climate under the A2 (a low mitigation) scenario of the Special Report on Emission Scenarios. High impact climate events such as heat-wave days and high fire-danger days are consistently projected to increase drastically in their frequency of occurrence. General decreases in soil-moisture availability are projected, even for regions where increases in rainfall are plausible, due to enhanced levels of evaporation. The regional dowscalings presented here, and recent GCM projections obtained for Africa, indicate that African annual-averaged temperatures may plausibly rise at about 1.5 times the global rate of temperature increase in the subtropics, and at a somewhat lower rate in the tropics. These projected increases although drastic, may be conservative given the model underestimations of observed temperature trends. The relatively strong rate of warming over Africa, in combination with the associated increases in extreme temperature events, may be key factors to consider when interpreting the suitability of global mitigation targets in terms of African climate change and climate change adaptation in Africa.
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A new activity index for acoustical bat data is presented. The AI (acoustic activity index) was highly correlated to bat passes but proved to be a less biased index of activity. The method dispenses with the need to define, identify and account bat passes and provides a simple means to quantify activity. It uses the Anabat system where acoustic surveys are carried out in real time with the data saved directly to a computer hard drive, taking advantage of the date-time information encoded into each file. The method is based upon the presence/absence of a species occurrence during one-minute time intervals and avoids skewing an index of activity that may reflect the behavior of the species sampled. Examples are given showing that the AI is an effective measure of bat activity allowing comparisons between sites, times and species.
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Bat distributions are still comparatively poorly known in Africa and updated national species lists do not exist for many countries. We present a revised checklist of the bats of Swaziland, which includes seven species not previously listed. Of these, two species are recent additions (Mops midas and Myotis bocagii) and these records marginally extend their known distributional range. A total of 26 species of bats are now known from the country , but additional surveys are predicted to add more taxa to the list. These new records predominantly come from human-modified landscapes, underscoring the importance of further surveys in such transformed habitats.
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Pest control through integrated pest management systems stands as a very convenient sustainable hazard-free alternative to pesticides, which are a growing global concern if overused. The ability of the soprano pipistrelle bat (Pipistrellus pygmaeus) to control the rice borer moth (Chilo supressalis), which constitutes a major pest of rice around the world, was studied in the Ebre Delta, Northeastern Iberia. Evidence was found on the ability of this particular bat species to control borer infestations: a) the moth was consumed during at least the last two peaks of the moth activity, when most crop damage is done; b) the activity of bats significantly increased with moth abundance in the rice paddies; c) the pest levels have declined in the study area (Buda Island, Eastern Ebre Delta) after the deployment of bat boxes and their subsequent occupation by soprano pipistrelles. The value of the ecosystem service provided by bats was estimated at a minimum of 21€ per hectare, equivalent to the avoided pesticide expenditure alone. We suggest that this natural service can be enhanced by providing bat populations with artificial roosts in rice paddies were some key ecosystem features are present.
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The Baixo Vouga Lagunar (BVL) landscape, in the Portuguese central-west coast, harbours a mosaic of wetland habitat types, interspersed by intensive and extensive agricul-tural fields, pastures, production forests and urban areas. In this study, we aimed to determine the species composition and the structure of the bat assemblages of the different habitats that constitute this heterogeneous landscape and to investigate seasonal changes in the patterns of bat diversity and activity across habitats. We acoustically sampled bats across 24 sam-pling sites representative of the eight main habitat types that shape the landscape—Bocage, forests, maize fields, marshlands, reed beds, rice fields, sea rushes and urban set-tlements. We compared bat richness, diversity and evenness across habitat types and seasons. We analysed habitat-specific and season-specific overall bat activity, and because habitat selection by bats is known to reflect morphological characters, foraging strategies and echolocation call structures, we also analysed the activity of individual species and of eco-morphological guilds. From 1,544 bat-passes recorded, we identified 12 species. Pipistrellus pygmaeus, Pipistrellus pipistrellus and Eptesicus serotinus/Eptesicus isabellinus were the most frequently recorded. Species composition and activity were similar across habitats, whilst exhibiting strong seasonal dynamics within habitats. Our results suggest that the mosaicism of the landscape provides several opportunities for bats, enabling them to explore different resources in distinct habitat patches. However, it may also reflect a forced exploi-tation of less optimal habitats and resources by bats, due to the scarcity of opportunities provided by fragmented landscapes.
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Maximum likelihood or restricted maximum likelihood (REML) estimates of the parameters in linear mixed-effects models can be determined using the lmer function in the lme4 package for R. As for most model-fitting functions in R, the model is described in an lmer call by a formula, in this case including both fixed- and random-effects terms. The formula and data together determine a numerical representation of the model from which the profiled deviance or the profiled REML criterion can be evaluated as a function of some of the model parameters. The appropriate criterion is optimized, using one of the constrained optimization functions in R, to provide the parameter estimates. We describe the structure of the model, the steps in evaluating the profiled deviance or REML criterion, and the structure of classes or types that represents such a model. Sufficient detail is included to allow specialization of these structures by users who wish to write functions to fit specialized linear mixed models, such as models incorporating pedigrees or smoothing splines, that are not easily expressible in the formula language used by lmer.
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The economic value of natural regulation of agricultural pests by bats has been estimated both by avoided cost models and by experimental predator-exclusion approaches. We review published studies globally from both complementary approaches. We further present an economic model for the avoided cost of bat predation on stinkbugs, the major economic pest of macadamias in South Africa, currently the world’s largest macadamia producer. We calculated both the direct (reduced stinkbug damage due to bat predation) and indirect (reduced pesticide use) avoided costs. We estimated the density of bats in a macadamia-growing region of South Africa to be 7.5–22.5 bats/ha, based on opportunistic data from the Merlin DeTEct (Inc.) avian-avoidance radar system. Current economic parameters for macadamia production, stinkbug injury coefficients and life history were obtained from the literature and from the Southern African Macadamia Association (SAMAC).We estimated the level of bat predation on pest stinkbugs in macadamia orchards from published dietary studies combined with both high and low published values for insect consumption rates relative to bat body mass. We found that the protected yield due to bat predation of stink bugs amounted to 0.53% (low consumption rates) to 1.29% (high consumption rates) of annual macadamia production in South Africa for 2015. Based on current macadamia prices, the approximate avoided cost values of these combined direct and indirect bat predation services varied between 9% and 23% of the current annual estimated cost of damage caused by stinkbugs to South African macadamia orchards (US$613/ha). Losing bats to disease epidemics, wind farms, human persecution or excessive or highly toxic pesticide applications could therefore significantly increase annual losses to the macadamia industry in South Africa caused by stinkbugs.
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Aim Across the planet, grass‐dominated biomes are experiencing shrub encroachment driven by atmospheric CO 2 enrichment and land‐use change. By altering resource structure and availability, shrub encroachment may have important impacts on vertebrate communities. We sought to determine the magnitude and variability of these effects across climatic gradients, continents, and taxa, and to learn whether shrub thinning restores the structure of vertebrate communities. Location Worldwide. Time period Contemporary. Major taxa studied Terrestrial vertebrates. Methods We estimated relationships between percentage shrub cover and the structure of terrestrial vertebrate communities (species richness, Shannon diversity and community abundance) in experimentally thinned and unmanipulated shrub‐encroached grass‐dominated biomes using systematic review and meta‐analyses of 43 studies published from 1978 to 2016. We modelled the effects of continent, biome, mean annual precipitation, net primary productivity and the normalized difference vegetation index (NDVI) on the relationship between shrub cover and vertebrate community structure. Results Species richness, Shannon diversity and total abundance had no consistent relationship with shrub encroachment and experimental thinning did not reverse encroachment effects on vertebrate communities. However, some effects of shrub encroachment on vertebrate communities differed with net primary productivity, amongst vertebrate groups, and across continents. Encroachment had negative effects on vertebrate diversity at low net primary productivity. Mammalian and herpetofaunal diversity decreased with shrub encroachment. Shrub encroachment also had negative effects on species richness and total abundance in Africa but positive effects in North America. Main conclusions Biodiversity conservation and mitigation efforts responding to shrub encroachment should focus on low‐productivity locations, on mammals and herpetofauna, and in Africa. However, targeted research in neglected regions such as central Asia and India will be needed to fill important gaps in our knowledge of shrub encroachment effects on vertebrates. Additionally, our findings provide an impetus for determining the mechanisms associated with changes in vertebrate diversity and abundance in shrub‐encroached grass‐dominated biomes.
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Code
Tools for performing model selection and model averaging. Automated model selection through subsetting the maximum model, with optional constraints for model inclusion. Model parameter and prediction averaging based on model weights derived from information criteria (AICc and alike) or custom model weighting schemes. [Please do not request the full text - it is an R package. The up-to-date manual is available from CRAN].
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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.
Article
The recent trend of agricultural intensification in tropical landscapes poses a new threat to biodiversity conservation. Conversion of previously heterogeneous agricultural landscapes to intensive plantation agriculture simplifies and homogenizes the landscape, reducing availability, and connectivity of natural habitat for native species. To assess the impact of agricultural intensification on bats, we charac- terized the bat assemblage in the Sarapiqui region of Costa Rica, where heterogeneous land uses are being converted to intensive, large- scale pineapple plantations. In 2012 and 2013, we sampled bats in 20 remnant forest patches surrounded by varying proportions of pasture, mature forest, and pineapple and captured 1821 individual bats representing 39 species. We used ordination analyses to evaluate changes in species composition, where pineapple is the main component of the agricultural matrix. We identified landscape metrics specifically correlated with pineapple and used multiple linear regression to test their effects on bat species richness, diversity, and guild- specific relative abundance. Results suggest pineapple expansion is driving changes in assemblage composition in remnant forest patches, resulting in new assemblages with higher proportions of frugivorous bats and lower proportions of insectivorous bats than in continuous mature forests. In addition, while pineapple does not diminish total bat species richness and diversity, the reduced forest cover and increased distance between forest patches in pineapple plantations has a significant negative impact on the relative abundance of insectivores. We also identify a potential threshold effect whereby patches surrounded by more than 50 percent forest can retain assemblage composition similar to that found in continuous mature forest.
Article
Global change will likely affect savanna and forest structure and distributions, with implications for diversity within both biomes. Few studies have examined the impacts of both expected precipitation and land-use changes on vegetation structure in the future, despite their likely severity. Here we modeled tree cover in Sub-Saharan Africa, as a proxy for vegetation structure and land cover change, using climatic, edaphic and anthropic data (R2 = 0.97). Projected tree cover for the year 2070, simulated using scenarios that include climate and land-use projections, generally decreased, both in forest and savanna, although the directionality of changes varied locally. The main driver of tree cover changes was land-use change; the effects of precipitation change were minor by comparison. Interestingly, carbon emissions mitigation via increasing biofuels production resulted in decreases in tree cover, more severe than scenarios with more intense precipitation change, especially within savannas. Evaluation of tree cover change against protected area extent at the WWF Ecoregion scale suggested areas of high biodiversity and ecosystem services concern. Those forests most vulnerable to large decreases in tree cover were also highly protected, potentially buffering the effects of global change. Meanwhile, savannas, especially where they immediately bordered forests (e.g. West and Central Africa), were characterized by a dearth of protected areas, making them highly vulnerable. Savanna must become an explicit policy priority in the face of climate and land use change if conservation and livelihoods are to remain viable into the next century. This article is protected by copyright. All rights reserved.
Article
The focus of conservation biology has been predominantly the study of single species, and conservation management and legislation has been directed mostly at the species level. Increasingly, however, there has been a recognition that ecosystems and landscapes need to be considered, since they form the physical and biotic context within which species exist. Increased emphasis on the landscape scale suggests that the emerging discipline of landscape ecology might have much to offer conservation biology. Landscape ecology is still a young science with no well-defined theoretical framework and little rigorous quantitative methodology. It aims to study patterns, processes and changes at the scale of hectares to square kilometers. Its focus on the pattern and dynamics of ecosystems or patches within a landscape offers much which is of relevance to conservation biology. Topics such as disturbance, patch dynamics, metapopulation dynamics, landscape flows, connectivity and fragmentation all have relevance to the conservation of biodiversity in natural, altered and rapidly changing systems. The papers in this issue provide a cross section of Australian research into landscape ecology which is of relevance to conservation biology. Methodological, theoretical and practical aspects are covered. I suggest that effective conservation of biodiversity will be achieved only if the landscape context is taken into account.
Article
Regression models allow us to isolate the relationship between the outcome and an explanatory variable while the other variables are held constant. Here, we introduce an R package, visreg, for the convenient visualization of this relationship via short, simple function calls. In addition to estimates of this relationship, the package also provides pointwise confidence bands and partial residuals to allow assessment of variability, outliers, and deviations from modeling assumptions. The package also provides several options for visualizing models with interactions, including lattice plots, contour plots, and both static and interactive perspective plots. The implementation of the package is designed to be as generic as possible, allowing visualization not only of linear models, but of generalized linear models (glm), proportional hazards models (coxph), generalized additive models (gam), robust regression models (rlm), and more.
Article
Aim To identify characteristics of a human‐modified landscape that promote taxonomic ( TD ), functional ( FD ) and phylogenetic ( PD ) dimensions of bat biodiversity. Location Caribbean lowlands of northeastern Costa Rica. Methods During the dry and wet seasons, we quantified TD (Simpson's diversity), as well as FD and PD (Rao's quadratic entropy) of phyllostomid bat assemblages at 15 sites that represented a forest loss and fragmentation gradient. FD was estimated separately for each of seven functional components that reflect particular niche axes (e.g. diet, foraging strategy) and for all functional components combined ( FD all ). PD was based on relatedness of species derived from a supertree. We identified the best explanatory landscape characteristics of each dimension using hierarchical partitioning. Results Landscape effects were dimension and season specific. During the dry season, TD and PD increased with increasing proportions of pasture or size of forest patches, whereas FD all decreased with increasing size of forest patches. During the wet season, TD increased with increasing forest patch size, whereas FD all and PD increased with increasing compactness of forest patches and decreasing proximity. Decomposition of FD into separate functional components revealed different landscape effects on ecological aspects of assemblages. Main conclusions One dimension of biodiversity was not a good surrogate for another. Rather, decomposition of biodiversity into different dimensions and functional components facilitated identification of the aspects of assemblages that are most affected by forest conversion and fragmentation. Areas with intermediate amounts of forest and pasture during the dry season harboured highest diversity from taxonomic, functional and phylogenetic perspectives. During the wet season, areas with large, compact forest patches promoted the dimensions of biodiversity. Placement of areas with even amounts of forest and pasture adjacent to large, compact forest patches (e.g. reserves) may maintain high biodiversity of bats and the ecosystem functions that they provide throughout the year.
Article
Agriculture is a dominant land use worldwide with approximately 40% of the land's surface used for farming. In many countries, particularly parts of Europe, this figure is substantially higher and most agricultural land is under intensive practices aimed at maximising the production of food. The intensification and expansion of modern agricultural practices led to the biological simplification of the farmed environment, which has resulted in declines in farmland biodiversity during the last century. As with other taxa, many bat species have suffered severe population declines during the 20th century, with agriculture believed to be one of the main drivers reducing roost availability and foraging habitat. Lower intensity farming methods, and the creation or management of habitat features on farmland could potentially mitigate some of these negative impacts but the effects of this on bats, in comparison to other taxa, have received relatively little attention. Here, I review evidence on the impacts of efforts to increase biodiversity in agricultural landscapes on bat populations, and explore whether responses of bats to agricultural activities are similar to those of other taxa, a necessary requirement if they are to be used as bioindicator species.
Article
S hipley, V ile & G arnier ( Science 2006; 314 : 812) proposed a maximum entropy approach to studying how species relative abundance is mediated by their traits, ‘community assembly via trait selection’ ( CATS ). In this paper, we build on recent equivalences between the maximum entropy formalism and Poisson regression to show that CATS is equivalent to a generalized linear model for abundance, with species traits as predictor variables. Main advantages gained by access to the machinery of generalized linear models can be summarized as advantages in interpretation, model checking, extensions and inference. A more difficult issue, however, is the development of valid methods of inference for single‐site data, as species correlation in abundance is not accounted for in CATS (whether specified as a regression or via maximum entropy). This issue can be circumvented for multisite data using design‐based inference. These points are illustrated by example – our plant abundances were found to violate the implicit P oisson assumption of CATS , but a negative binomial regression had much improved fit, and our model was extended to multisite data in order to directly model the environment–trait interaction. Violations of the P oisson assumption were strong and accounting for them qualitatively changed results, presumably because larger counts had undue influence when overdispersion had not been accounted for. We advise that future CATS analysts routinely check for overdispersion and account for it if present.