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.
Fragmentation is one of the most important drivers of global biodiversity loss. In this article we study the effects of seasonality on the responses of Neotropical bats to local‐ and landscape‐scale attributes in a fragmented landscape.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Habitat fragmentation is one of the greatest threats to biodiversity. Despite their importance for conservation, the genetic consequences of small-scale habitat fragmentation for bat populations are ...largely unknown. In this study, we linked genetic with ecological and demographic data to assess the effects of habitat fragmentation on two species of phyllostomid bats (Uroderma bilobatum and Carollia perspicillata) that differ in their dispersal abilities and demographic response to fragmentation. We hypothesized that population differentiation and the effect of habitat fragmentation on levels of genetic diversity will be a function of the species' mobility. We sequenced mtDNA from 232 bats caught on 11 islands in Gatún Lake, Panamá, isolated from the mainland for ca 90 yr, and in adjacent, continuous forest on the mainland. Populations of both species showed significant genetic differentiation (FST). Consistent with our prediction, population subdivision was lower in the highly mobile U. bilobatum (FST= 0.01) compared to the less vagile C. perspicillata (FST= 0.06), and only the latter species showed a pattern indicative of isolation by distance and, in addition, an effect of fragmentation. Genetic erosion as a result of fragmentation was also only detectable in the less mobile species, C. perspicillata, where haplotype diversity was lower in island compared to mainland populations. Our results suggest that some Neotropical bat species are prone to loss of genetic variation in response to anthropogenic small-scale habitat fragmentation. In this context, our findings point toward mobility as a good predictor of a species' vulnerability to fragmentation and altered population genetic structure.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Understanding the consequences of habitat modification on wildlife communities is central to the development of conservation strategies. However, albeit male and female individuals of numerous ...species are known to exhibit differences in habitat use, sex-specific responses to habitat modification remain little explored. Here, we used a landscape-scale fragmentation experiment to assess, separately for males and females, the effects of fragmentation on the abundance of Carollia perspicillata and Rhinophylla pumilio, two widespread Neotropical frugivorous bats. We predicted that sex-specific responses would arise from higher energetic requirements from pregnancy and lactation in females. Analyses were conducted independently for each season, and we further investigated the joint responses to local and landscape-scale metrics of habitat quality, composition, and configuration. Although males and females responded similarly to a fragmentation gradient composed by continuous forest, fragment interiors, edges, and matrix habitats, we found marked differences between sexes in habitat use for at least one of the seasons. Whereas the sex ratio varied little in continuous forest and fragment interiors, females were found to be more abundant than males in edge and matrix habitats. This difference was more prominent in the dry season, the reproductive season of both species. For both species, abundance responses to local-and landscape-scale predictors differed between sexes and again, differences were more pronounced in the dry season. The results suggest considerable sex-mediated responses to forest disruption and degradation in tropical bats and complement our understanding of the impacts of fragmentation on tropical forest vertebrate communities.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Objective
To assess the benefits and safety of early human fibrinogen concentrate in postpartum haemorrhage (PPH) management.
Design
Multicentre, double‐blind, randomised placebo‐controlled trial. ...Setting: 30 French hospitals.
Population
Patients with persistent PPH after vaginal delivery requiring a switch from oxytocin to prostaglandins.
Methods
Within 30 minutes after introduction of prostaglandins, patients received either 3 g fibrinogen concentrate or placebo.
Main outcome measures
Failure as composite primary efficacy endpoint: at least 4 g/dl of haemoglobin decrease and/or transfusion of at least two units of packed red blood cells within 48 hours following investigational medicinal product administration. Secondary endpoints: PPH evolution, need for haemostatic procedures and maternal morbidity–mortality within 6 ± 2 weeks after delivery.
Results
437 patients were included: 224 received FC and 213 placebo. At inclusion, blood loss (877 ± 346 ml) and plasma fibrinogen (4.1 ± 0.9 g/l) were similar in both groups (mean ± SD). Failure rates were 40.0% and 42.4% in the fibrinogen and placebo groups, respectively (odds ratio OR = 0.99) after adjustment for centre and baseline plasma fibrinogen; (95% CI 0.66–1.47; P = 0.96). No significant differences in secondary efficacy outcomes were observed. The mean plasma FG was unchanged in the Fibrinogen group and decreased by 0.56 g/l in the placebo group. No thromboembolic or other relevant adverse effects were reported in the Fibrinogen group versus two in the placebo group.
Conclusions
As previous placebo‐controlled studies findings, early and systematic administration of 3 g fibrinogen concentrate did not reduce blood loss, transfusion needs or postpartum anaemia, but did prevent plasma fibrinogen decrease without any subsequent thromboembolic events.
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Early systematic blind 3 g fibrinogen infusion in PPH did not reduce anaemia or transfusion rate, reduced hypofibrinogenaemia and was safe.
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Early systematic blind 3 g fibrinogen infusion in PPH did not reduce anaemia or transfusion rate, reduced hypofibrinogenaemia and was safe.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Bats feature prominently among organisms that occupy the aerosphere as they extensively use this environment for foraging, but also for dispersal, migration, and behavioral interactions. Differential ...use of the aerosphere is an important factor structuring bat assemblages, with species exhibiting distinct morphological, physiological, and sensory adaptations to different habitat types. This necessitates comprehensive sampling methodologies such as combined ground-level and canopy-level mist netting as well as acoustic monitoring to assess the presence, diversity, and activity of different functional groups of species adequately. Recent technological advances in acoustic detection and in methods of analysis, coupled with the expansion of libraries of echolocation calls for species identification, now allow for the reliable quantification of species numbers and activity of the scarcely known group of aerial insectivorous bats, particularly in species-rich tropical assemblages. We provide a brief, exemplary overview of recent studies on bats conducted in Panamá to demonstrate the necessity of comprehensive sampling methods and application of new technologies in order to adequately depict assemblage composition and responses of bats to structural changes in habitats induced by fragmentation. In addition to acoustic methods, miniaturization of radio transmitters has provided new insights into the patterns of spatial use of the aerosphere by bats and has identified species-specific differences in mobility as one of the important traits that determines bats' reactions to anthropogenic alterations of the landscape. Following the goals of the symposium on aeroecology, we propose new avenues of research for probing the aerosphere. We discuss how integration of a diverse array of remote sensing tools with data on species distribution and species traits, such as mobility and edge-sensitivity, might provide novel opportunities for the development, and application of conservation-oriented monitoring systems.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
1. Species richness is a state variable of some interest in monitoring programmes but raw species counts are often biased due to imperfect species detectability. Therefore, monitoring programmes ...should quantify detectability for target taxa to assess whether it varies over temporal or spatial scales. We assessed the potential for tropical bat monitoring programmes to reliably estimate trends in species richness. 2. Using data from 25 bat assemblages from the Old and New World tropics, we estimated detectability for all species in an assemblage (mean proportion of species detected per sampling plot) and for individual species (species-specific detectability). We further assessed how these estimates of detectability were affected by external sources of variation relating to time, space, survey effort and biological traits. 3. The mean proportion of species detected across 96 sampling plots was estimated at 0·76 (range 0·57—1·00) and was significantly greater for phytophagous than for animalivorous species. Species-averaged detectability for phytophagous species was influenced by the number of surveys and season, whereas the number of surveys and sampling methods ground- or canopy-level mist nets, harp traps and acoustic sampling (AS) most strongly affected estimates of detectability for animalivorous bats. Species-specific detectability averaged 0·4 and was highly heterogeneous across 232 species, with estimates ranging from 0·03 to 0·84. Species-level detectability was influenced by a range of external factors such as location, season, or sampling method, suggesting that raw species counts may sometimes be strongly biased. 4. Synthesis and applications. Due to generally high species-specific detection probabilities, Neotropical aerial insectivorous bats proved to be well suited for monitoring using AS. However, for species with low detectability, such as most gleaning animalivores or nectarivores, count data obtained in bat monitoring surveys must be corrected for detection bias. Our results indicate that species-averaged detection probabilities will rarely approach 1 unless many surveys are conducted. Consequently, long-term bat monitoring programmes need to adopt an estimation scheme that corrects for variation in detectability when comparing species richness over time and when making regional comparisons. Similar corrections will be needed for other species-rich tropical taxa.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Bats are ecologically important mammals in tropical ecosystems; however, their populations face numerous environmental threats related to climate change, habitat loss, fragmentation, hunting, and ...emerging diseases. Thus, there is a pressing need to develop and implement large-scale networks to monitor trends in bat populations over extended time periods. Using data from a range of Neotropical and Paleotropical bat assemblages, we assessed the ability for long-term monitoring programs to reliably detect temporal trends in species abundance. We explored the magnitude of within-site temporal variation in abundance and evaluated the statistical power of a suite of different sampling designs for several different bat species and ensembles. Despite pronounced temporal variation in abundance of most tropical bat species, power simulations suggest that long-term monitoring programs (⩾20
years) can detect population trends of 5% per year or more with adequate statistical power (⩾0.9). However, shorter monitoring programs (⩽10
years) have insufficient power for trend detection. Overall, our analyses demonstrate that a monitoring program extending over 20
years with four surveys conducted biennially on five plots per monitoring site would have the potential for detecting a 5% annual change in abundance for a suite of bat species from different ensembles. The likelihood of reaching adequate statistical power was sensitive to initial species abundance and the magnitude of count variation, stressing that only the most abundant species in an assemblage and those with generally low variation in abundance should be considered for detailed population monitoring.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for ...evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional forest space, studies are biased towards understory-based surveys and only few assessments of vertical stratification were done in fragmented landscapes. Using both ground and canopy mist-nets, we investigated how the vertical structure of bat assemblages is influenced by forest fragmentation in the experimentally fragmented landscape of the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Over a three year-period, we captured 3077 individuals of 46 species in continuous forest (CF) and in 1, 10 and 100 ha forest fragments. In both CF and forest fragments, the upper forest strata sustained more diverse bat assemblages than the equivalent understory layer, and the midstory layers had significantly higher bat abundance in fragments than in CF. Artibeus lituratus and Rhinophylla pumilio exhibited significant shifts in their vertical stratification patterns between CF and fragments (e.g., R. pumilio was more associated with the upper strata in fragments than in CF). Altogether, our study suggests that fragmentation modulates the vertical stratification of bat assemblages.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Recent studies predict a future decrease in precipitation across the tropics, particularly the Amazon, likely causing significant droughts that have negative consequences for Amazonian freshwater ...biomes, especially lakes. Furthermore, immediate consequences of global warming for terrestrial fauna associated with tropical lakes are poorly understood as the vast majority of studies come from temperate regions. Here, we assess the seasonal importance of lakes for the conservation of aerial insectivorous bats in the Central Amazon using passive bat recorders. We compared richness, general bat activity and foraging activity between lakes and adjacent forest. Of a total of 21 species/sonotypes recorded in both habitats, all were detected over lakes, and 18 were significantly more active over lakes than in forest. Only two species had significantly higher activity levels in the forest than at the lakes. Species richness and general bat activity over the lakes were higher in the dry than in the rainy season. Foraging activity was also greater over the lakes than within the forest in both seasons. Moreover, both variables were positively correlated with lake size, although the effect on activity was species‐specific. Climate change‐driven shrinking of lakes may have detrimental consequences for aerial insectivorous bats, especially for the most water‐dependent species. Compared to permanent water bodies of other regions, the value of tropical lakes for functionally important taxa, such as bats, has been understudied. Higher bat activity levels over lakes than in forest in both seasons and comprising the whole ensemble of aerial insectivorous bats of the study region, indicate that lakes embedded in Amazonian terra firme forests deserve special attention for future bat conservation.
Recent studies predict a future decrease in precipitation across the tropics, particularly the Amazon, likely causing significant droughts with negative consequences for water bodies. We assessed the seasonal importance of lakes for the conservation of aerial insectivorous bats in the Amazon using autonomous recorders. We compared richness, bat activity and foraging activity between lakes and forest. Of 21 species/sonotypes identified, all were detected over lakes, and 18 of them were significantly more active over water bodies than in forest. During the dry season, richness and bat activity over the lakes were higher than in the rainy season. Both variables were positively correlated with lake size, although bat activity influence was species‐specific. Climate change‐driven shrinking of lakes may have detrimental consequences for insectivorous bats, especially the most water‐dependent species. Our results indicate that lakes embedded in Amazonian terra firme forests deserve special attention for bat conservation as their interactions have clearly been understudied.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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