Hourly activity patterns of the insectivorous bat assemblage in the urban–rural landscape of Lima, Peru

Abstract

Circadian rhythms of bats are simultaneously influenced by both abiotic and biotic factors that vary across different landscapes. Since cities modify environmental conditions in which bats forage and roost, their temporal activity can be altered. Based on acoustic surveys, we described hourly activity patterns of eight aerial insectivorous bat species in an urban–rural landscape of Lima, Peru. We also explored whether bats show temporal partitioning at the assemblage level and, for three common species, if activity patterns change between landscape units (urban and rural areas) or moonlight intensity (dark and bright nights). At the assemblage level, bats displayed high temporal overlap, especially in rural areas. At the species level, Mormopterus kalinowskii and Tadarida brasiliensis displayed bimodal patterns at both landscape units, and Promops davisoni showed an almost uniform pattern or bimodal pattern at urban and rural sites, respectively. In rural areas, other bat species exhibited either unimodal patterns (Nyctinomops laticaudatus, N. aurispinosus, N. macrotis, and Tomopeas ravus) or a bimodal pattern (Myotis). Moonlight intensity had little influence on activity periods of most bat species. Our study provides valuable information for sampling designs and future studies on activity patterns focused on coexistence among insectivorous bat species in arid landscapes.

Conservation Value to Bats: Assessing Multiple Functional Habitats in a Nature Preserve at the Urban-Agricultural Interface via Temporal Ecology

“…Additionally, the previous research was conducted in more natural environments, whereas ours is conducted at the urban-agricultural interface. Urbanization has been known to alter bat temporal niche partitioning [28,86]. Another plausible explanation is that the fieldwork time window in the previous research covered more months within a year than ours.…”

“…To examine how bat diel activity patterns might vary/overlap among species between open and edge sites, we followed the nonparametric kernel density estimate procedure via the R package "overlap" [56]. This procedure has been used in similar bat research [28,30]. We converted the timestamp of each recording into a radian scale (sunset/0% of the night as 0 and sunrise/100% of the night as 2π).…”

“…Variations of a species' diel activity patterns may occur when bats respond to changes or disturbances in the environment, such as seasonality, anthropogenic light, or noises [25][26][27]. When a species' diel activity patterns vary across different habitats, it indicates differences in how bats use these habitats and what resources each habitat might provide [28][29][30]. Another aspect of temporal ecology is examining bat activity patterns across nights, months, or even years.…”