Habitat disturbance trumps moonlight effects on the activity of tropical insectivorous bats

Aerial insectivorous bats in the Brazilian-Uruguayan savanna: Modelling the occupancy through acoustic detection

The Pampa is the least protected and one of the least sampled for bats among the Brazilian domains. This leads to significant Linnean and Wallacean shortfalls for bats in the Brazilian-Uruguayan savanna ecoregion. Here, we aimed to model the occupancy of aerial insectivorous bats in response to landscape structure at different scales, considering the influence of microclimate on bat detection. We acoustically monitored 68 locations during the spring and summer of 2019/2020, gathering data on temperature and humidity associated with each acoustic record using data loggers. We detected at least 11 species of the Molossidae and the Vespertilionidae families, of which 9 were used in the model. The response to landscape structure was species-specific: the occupancy probability of Eptesicus brasiliensis and Molossus cf. currentium increased with landscape connectivity at the 500 m scale while Eptesicus furinalis and Histiotus cf. velatus were negatively affected by landscape connectivity at the 5.0 km scale. Molossus occupancy probability responded negatively to landscape heterogeneity at the 3.0 km scale, while Promops centralis responded positively to landscape heterogeneity at the 5.0 km scale. Molossus rufus responded negatively to native vegetation cover and positively to landscape heterogeneity at the 5.0 km scale. Myotis albescens and Molossops temminckii did not respond significantly to any of the evaluated landscape metrics. Our results show that different bat species perceive the landscape differently, regardless of the guild of use of space – edge- or open-space forager. Our estimate of projected occupancy for the areas contiguous to those sampled ranged from 0.45 to 0.70 for the whole of the bat taxa, suggesting that the landscape, particularly where it still maintains its native elements, is reasonably favourable to aerial insectivores.

Negative effects of light pollution on pollinator visits are outweighed by positive effects on the reproductive success of a bat-pollinated tree

Cities are home to several species of pollinators that play an important role in the reproductive success of wild and cultivated plants that grow in these ecosystems and their surroundings. Pollution is a main driver of pollinator decline. Light and noise pollution are more intense in cities than in any other ecosystem. Although nocturnal pollinators are heavily exposed to these pollutants, their effect on bat pollination is still unknown. Our goal was to assess the effect of light and noise pollution on the main pollination components (pollinator visits, pollen transfer, pollen germination, fruit, and seed set) of the tropical tree, Ceiba pentandra, in a heavily urbanized ecosystem. We measured these components in sites with contrasting intensities of artificial light and anthropogenic noise and statistically assessed the direct and indirect effect of pollutants on pollination components using structural equation modeling. We found that noise and light pollution negatively affected the visits by the bats that pollinate C. pentandra. However, these negative effects did not affect posterior pollination components. In fact, the direct effect of light pollution on reproductive success was positive and greater than the indirect effects via pollinator visits. We suggest that illuminated trees may be able to sustain a large quantity of fruits and seeds because they produce more photosynthates due to greater light radiation and delayed leaf abscission. We conclude that, despite the negative effect of light and noise on pollinator visits, these pollutants did not significantly impact the reproductive success of C. pentandra.