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Jung, K., & Kalko, E. K. (2010). Where forest meets urbanization: foraging plasticity of aerial insectivorous bats in an anthropogenically altered environment. J. Mammal., 91(1), 144–153.
Abstract: Given worldwide rapid human population growth resulting in degradation or loss of habitats, it is important to understand how anthropogenic factors affect species presence and activity, and consequently, how well species tolerate or adapt to anthropogenically altered environments. This study, conducted in Panama, focuses on aerial insectivorous bats, a highly mobile and ecologically important, but largely understudied group. Acoustic monitoring was used to investigate habitat use in a tropical forest-town interface and microhabitat use around streetlights differing in wavelength (type of light) and accessibility (distance to vegetation). Plasticity in microhabitat use also was examined in relation to season and moonlight. We recorded a total of 25 aerial insectivorous bat species in the study area and found a subset of 20 species in town of which 18 frequently foraged around streetlights. Bat activity (passes/min) was lowest at the forest site, highest at streetlights, and intermediate in the dark areas of town. General bat activity at streetlights was concentrated at bluish-white lights compared to yellow-white and orange lights. However, bats revealed species-specific microhabitats with regard to light type, distance to vegetation, and relative light intensity. Season and moon phase affected microhabitat use around streetlights leading to microhabitat plasticity of individual species. Thus, in the forest-town interface most, but not all, aerial insectivorous bats were present in town and regularly foraged around streetlights, suggesting a species-specific tolerance for habitat alteration. Bats foraging at streetlights used microhabitats, and some species even changed microhabitats, according to season or moon phase. This indicates species-specific requirements for microhabitats and the importance of preserving habitat heterogeneity.
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Mathews, F., Roche, N., Aughney, T., Jones, N., Day, J., Baker, J., et al. (2015). Barriers and benefits: implications of artificial night-lighting for the distribution of common bats in Britain and Ireland. Philos Trans R Soc Lond B Biol Sci, 370, 20140124.
Abstract: Artificial lighting is a particular problem for animals active at night. Approximately 69% of mammal species are nocturnal, and one-third of these are bats. Due to their extensive movementsâboth on a nightly basis to exploit ephemeral food supplies, and during migration between roostsâbats have an unusually high probability of encountering artificial light in the landscape. This paper reviews the impacts of lighting on bats and their prey, exploring the direct and indirect consequences of lighting intensity and spectral composition. In addition, new data from large-scale surveys involving more than 265 000 bat calls at more than 600 locations in two countries are presented, showing that prevalent street-lighting types are not generally linked with increased activity of common and widespread bat species. Such bats, which are important to ecosystem function, are generally considered âlight-attractedâ and likely to benefit from the insect congregations that form at lights. Leisler's bat (Nyctalus leisleri) may be an exception, being more frequent in lit than dark transects. For common pipistrelle bats (Pipistrellus pipistrellus), lighting is negatively associated with their distribution on a landscape scale, but there may be local increases in habitats with good tree cover. Research is now needed on the impacts of sky glow and glare for bat navigation, and to explore the implications of lighting for habitat matrix permeability.
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Orbach, D. N., & Fenton, B. (2010). Vision impairs the abilities of bats to avoid colliding with stationary obstacles. PLoS One, 5(11), e13912.
Abstract: BACKGROUND: Free-flying insectivorous bats occasionally collide with stationary objects they should easily detect by echolocation and avoid. Collisions often occur with lighted objects, suggesting ambient light may deleteriously affect obstacle avoidance capabilities. We tested the hypothesis that free-flying bats may orient by vision when they collide with some obstacles. We additionally tested whether acoustic distractions, such as “distress calls” of other bats, contributed to probabilities of collision. METHODOLOGY/PRINCIPAL FINDINGS: To investigate the role of visual cues in the collisions of free-flying little brown bats (Myotis lucifugus) with stationary objects, we set up obstacles in an area of high bat traffic during swarming. We used combinations of light intensities and visually dissimilar obstacles to verify that bats orient by vision. In early August, bats collided more often in the light than the dark, and probabilities of collision varied with the visibility of obstacles. However, the probabilities of collisions altered in mid to late August, coincident with the start of behavioural, hormonal, and physiological changes occurring during swarming and mating. Distress calls did not distract bats and increase the incidence of collisions. CONCLUSIONS/SIGNIFICANCE: Our findings indicate that visual cues are more important for free-flying bats than previously recognized, suggesting integration of multi-sensory modalities during orientation. Furthermore, our study highlights differences between responses of captive and wild bats, indicating a need for more field experiments.
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Saldaña-Vázquez, R. A., & MunguÃa-Rosas, M. A. (2013). Lunar phobia in bats and its ecological correlates: A meta-analysis. Mammalian Biology – Zeitschrift für Säugetierkunde, 78(3), 216–219.
Abstract: Animals show several behavioral strategies to reduce predation risks. Presumably, moonlight avoidance is a strategy used by some nocturnal species to reduce the risk of predation. In bats, some research indicates that foraging activity is negatively correlated with moonlight intensity, a phenomenon better known as lunar phobia. However, the currently available evidence is contradictory because some bat species reduce their activity during nights with more moonlight while the opposite occurs in other species. We quantitatively evaluated the strength and direction of the relationship between moonlight intensity and bat activity using a meta-analysis. We also looked at some ecological correlates of lunar phobia in bats. Specifically, we examined foraging habitat and latitude as potential moderators of the size of the lunar phobia effect. Our results show that, regardless of the method used to evaluate bat activity, the overall relationship between moonlight intensity and bat activity is significant and negative (r = −0.22). Species foraging on the surface of the water (piscivores and insectivores; r = −0.83) and forest canopy species (i.e., big frugivores; r = −0.30) are more affected by moonlight than those with different foraging habitats (understory, subcanopy, open air). Latitude was positively correlated with lunar phobia (r = 0.023). The stronger lunar phobia for bats foraging on the water surface and in the forest canopy may suggest that the risk of predation is greater where moonlight penetrates more easily. The significant effect of latitude as a moderator of lunar phobia suggests that there is a weak geographic pattern, with this phobia slightly more common in tropical bats than in temperate species.
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Stone, E. L., Jones, G., & Harris, S. (2009). Street lighting disturbs commuting bats. Curr Biol, 19(13), 1123–1127.
Abstract: Anthropogenic disturbance is a major cause of worldwide declines in biodiversity. Understanding the implications of this disturbance for species and populations is crucial for conservation biologists wishing to mitigate negative effects. Anthropogenic light pollution is an increasing global problem, affecting ecological interactions across a range of taxa and impacting negatively upon critical animal behaviors including foraging, reproduction, and communication (for review see). Almost all bats are nocturnal, making them ideal subjects for testing the effects of light pollution. Previous studies have shown that bat species adapted to foraging in open environments feed on insects attracted to mercury vapor lamps. Here, we use an experimental approach to provide the first evidence of a negative effect of artificial light pollution on the commuting behavior of a threatened bat species. We installed high-pressure sodium lights that mimic the intensity and light spectra of streetlights along commuting routes of lesser horseshoe bats (Rhinolophus hipposideros). Bat activity was reduced dramatically and the onset of commuting behavior was delayed in the presence of lighting, with no evidence of habituation. These results demonstrate that light pollution may have significant negative impacts upon the selection of flight routes by bats.
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