A small-scale response of urban bat activity to tree cover

Citizen Science Helps Uncover the Secrets to a Bat-Friendly Swimming Pool in an Urban Environment

For urban environments to support bat communities, resources need to be readily available. For example, bats typically use urban water sources such as drainage ditches and ponds; however, these sources can be ephemeral. During these periods, bats have utilized residential swimming pools, although they only appear to drink at pools when access to more natural equivalents are limited. This posed the question “can we make residential swimming pools friendlier for a diversity of bat species?” Using citizen science to determine which pool characteristics influenced bat activity, we distributed a questionnaire to residents in a suburban neighborhood in Fort Worth, TX, United States. It focused on observations of bat activity and the features of the pools and immediate surroundings. We distributed the questionnaire through social media, local presentations, and by mail throughout 2019 and 2020. We then used classification trees to determine which characteristics in combination influenced bat activity at the pools. We generated three different trees for bats observed (1) flying around the property and backyard, (2) above the swimming pool, and (3) drinking at the pool. We found that more bats were observed at unlit pools without bush or shrub borders. Furthermore, among pools with borders, activity was lowest at pools with textured interiors and ≥6 trees visible. The presence of features, such as fountains, then contributed to a reduction in bat observations in backyards and the presence of pets appeared to further reduce activity specifically over the pools. Where bats were observed drinking, this activity was reported the least at pools with bush or shrub borders, textured interiors, and trees <5 m and >10 m from the edge of the pools. Our study revealed that certain characteristics of residential swimming pools encouraged bat activity, while others discouraged them. Thus, it may be possible to make swimming pools more bat-friendly. For example, turning lights off in the evening when backyards are not in use and reducing clutter around pools could have an immediate positive impact on local bat populations. The implementation of such recommendations could improve urban habitats for bats overall and alleviate some of the negative implications of continued urbanization.

Occurrence of lemurs in landscapes and their species-specific scale responses to habitat loss

Studies on the impact of habitat loss on species occurrence consistently find that the amount of habitat (measured as patch area) is a major determinant of species occurrence at a patch-level. However, patch-level research may fail to detect important patterns and processes only observable at a landscape-level. A landscape-level approach that incorporates species-specific scale responses is needed to better understand what drives species occurrence. Our aim was to determine the landscape-level scale of effect of habitat amount on the occurrence of three species of nocturnal lemurs (Cheirogaleus medius, Microcebus murinus, and M. ravelobensis). We surveyed line transects to determine the occurrence of three lemur species within a fragmented landscape of deciduous dry forest and anthropogenic grassland in northwestern Madagascar. To determine the scale of effect of habitat loss on lemur occurrence, we compared logistic regression models of occurrence against habitat amount among eight different landscape scales using Akaike's Information Criterion values. We found differing scale responses among the lemurs in our study. Occurrence of C. medius responded to habitat amount at scales between 0.5-4 ha, M. murinus at scales between 1 and 4 ha and M. ravelobensis at scales between 0.125 and 4 ha. We suggest that the scale of effect for C. medius is mediated by their ability to hibernate. A relatively lower scale-response for Microcebus spp. likely reflect their omnivorous diet, small habitat requirements, and limited dispersal ability. Differences in scale responses between M. murinus and M. ravelobensis are likely a result of differing dispersal ability and responses to edge effects between these species. Our study is among the first on lemurs to show the value of a landscape-level approach when assessing the effects of habitat loss on species occurrence.