Guild Vertical Stratification and Drivers of Bat Foraging in a Semi-Arid Tropical Region, Kenya.

Africa faces significant challenges in reconciling economic and social development while preserving its natural resources. Little is known about the diverse bat community on the continent, particularly in drier ecosystems. A better understanding of the bat community will help improve and inform the management of these ecosystems. Our study aimed to provide detailed information on the main drivers of bat richness and activity at three different heights above the ground in a semi-arid region of Kenya. We assessed how bat activity varied with space and height using acoustic sampling and complementary methods. We sampled 48 sites at ground level and two sites on meteorological masts at 20 m and 35 m above the ground. We recorded more than 20 bat species, including one species of concern for conservation. Our models showed that the use of space varies with bat guild, creating trade-offs in the variables that affect their activity. Low-flying bat species are mostly associated with habitat variables, whereas high-flying species are more dependent on weather conditions. Our study highlights the richness of bat assemblages in semi-arid environments and emphasizes the need for management measures to protect bat diversity in the face of habitat degradation caused by climate change, land management, and development projects.

Integration of mark-recapture and acoustic detections for unbiased population estimation in animal communities.

Abundance estimation methods that combine several types of data are becoming increasingly common because they yield more accurate and precise parameter estimates and predictions than are possible from a single data source. These beneficial effects result from increasing sample size (through data pooling) and complementarity between different data types. Here, we test whether integrating mark-recapture data with passive acoustic detections into a joint likelihood improves estimates of population size in a multi-guild community. We compared the integrated model to a mark-recapture-only model using simulated data first and then using a data set of mist-net captures and acoustic recordings from an Afrotropical agroforest bird community. The integrated model with simulated data improved accuracy and precision of estimated population size and detection parameters. When applied to field data, the integrated model was able to produce, for each bird guild, ecologically plausible estimates of population size and detection parameters, with more precision compared with the mark-recapture model. Overall, our results show that adding acoustic data to mark-recapture analyses improves estimates of population size. With the increasing availability of acoustic recording devices, this data collection technique could readily be added to routine field protocols, leading to a cost-efficient improvement of traditional mark-recapture population estimation.

Second-growth and small forest clearings have little effect on the temporal activity patterns of Amazonian phyllostomid bats.

Secondary forests and human-made forest gaps are conspicuous features of tropical landscapes. Yet, behavioral responses to these aspects of anthropogenically modified forests remain poorly investigated. Here, we analyze the effects of small human-made clearings and secondary forests on tropical bats by examining the guild- and species-level activity patterns of phyllostomids sampled in the Central Amazon, Brazil. Specifically, we contrast the temporal activity patterns and degree of temporal overlap of 6 frugivorous and 4 gleaning animalivorous species in old-growth forest and second-growth forest and of 4 frugivores in old-growth forest and forest clearings. The activity patterns of frugivores and gleaning animalivores did not change between old-growth forest and second-growth, nor did the activity patterns of frugivores between old-growth forest and clearings. However, at the species level, we detected significant differences for Artibeus obscurus (old-growth forest vs. second-growth) and A. concolor (old-growth forest vs. clearings). The degree of temporal overlap was greater than random in all sampled habitats. However, for frugivorous species, the degree of temporal overlap was similar between old-growth forest and second-growth; whereas for gleaning animalivores, it was lower in second-growth than in old-growth forest. On the contrary, forest clearings were characterized by increased temporal overlap between frugivores. Changes in activity patterns and temporal overlap may result from differential foraging opportunities and dissimilar predation risks. Yet, our analyses suggest that activity patterns of bats in second-growth and small forest clearings, 2 of the most prominent habitats in humanized tropical landscapes, varies little from the activity patterns in old-growth forest.

Water utilities performance analysis in developing countries: On an adequate model for universal access.

The results of the analysis of water utility performance studies based on data envelopment analysis (DEA) can be very sensitive to the methodological approach and the variables employed. This study investigates approaches and variables for developing countries in order to identify an adequate model for universal access. Three models were developed and compared. The first used traditional variables, the second considered the quality of service variables, and the last are expanded on the second by incorporating the realization of the human right to water into efficiency estimation. Methodological approaches comprising the variable returns to scale DEA (most common for developing countries) and slack-based directional distance function (employed in this study) were also compared. The case study of 77 Brazilian water utilities suggests that a model that incorporates the objective of universal access in the efficiency estimation changes substantialy utility efficiency scores. Therefore, utilities that make investments to reach the universal access can be penalized since traditional models incorporate the expenses, but fail to capture the results. The research conclusions suggest that approaches and variable choices are likely to impact on the analysis results, misrepresenting them regardless of the purpose for using DEA in the study.

Season-modulated responses of Neotropical bats to forest fragmentation.

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.