Time of night and moonlight structure vertical space use by insectivorous bats in a Neotropical rainforest: an acoustic monitoring study

Abstract

Background Previous research has shown diverse vertical space use by various taxa, highlighting the importance of forest vertical structure. Yet, we know little about vertical space use of tropical forests, and we often fail to explore how this three-dimensional space use changes over time. Methods Here we use canopy tower systems in French Guiana and passive acoustic monitoring to measure Neotropical bat activity above and below the forest canopy throughout nine nights. We use a Bayesian generalized linear mixed effect model and kernel density estimates to demonstrate patterns in space-use over time. Results We found that different bats use both canopy and understory space differently and that these patterns change throughout the night. Overall, bats were more active above the canopy (including Cormura brevirostris, Molossus molossus, Peropteryx kappleri and Peropteryx macrotis), but multiple species or acoustic complexes (when species identification was impossible) were more active in the understory (such as Centronycteris maximiliani, Myotis riparius, Pteronotus alitonus and Pteronotus rubiginosus). We also found that most bats showed temporally-changing preferences in hourly activity. Some species were less active (e.g., P. kappleri and P. macrotis), whereas others were more active (Pteronotus gymnonotus, C. brevirostris, and M. molossus) on nights with higher moon illuminance. Discussion Here we show that Neotropical bats use habitat above the forest canopy and within the forest understory differently throughout the night. While bats generally were more active above the forest canopy, we show that individual groups of bats use space differently over the course of a night, and some prefer the understory. This work highlights the need to consider diel cycles in studies of space use, as animals use different habitats during different periods of the day.

Should I use fixed effects or random effects when I have fewer than five levels of a grouping factor in a mixed-effects model?

“…Often researchers (sometimes nudged by peer-reviewers) cite this guideline of needing 5 levels before random effects inclusion as a reason why they were unable to use a mixed-effects model ( Bain, Johnson & Jones, 2019 ; Bussmann & Burkhardt-Holm, 2020 ; Evans & Gawlik, 2020 ; Gomes & Goerlitz, 2020 ; Zhao, Johnson-Bice & Roth, 2021 ). Although there is confusion over this recommendation, as some opt to use mixed-effects models despite this suggestion ( Latta et al, 2018 ; Fugère, Lostchuck & Chapman, 2020 ; Gomes, Appel & Barber, 2020 ; Allen et al, 2021 ), likely because of the numerous advantages that mixed-effects models offer ( Bolker, 2008 ; Kéry & Royle, 2015 ; Harrison et al, 2018 ). There may be a trend to follow this rule given that authors or peer-reviewers can easily point out that this rule exists ( Gelman & Hill, 2006 ; Harrison, 2015 ; Kéry & Royle, 2015 ; Harrison et al, 2018 ; Arnqvist, 2020 ), but may find it more difficult or time-consuming to make a nuanced argument against following such a rapidly growing rule.…”

“…Indeed, in each of the above segments of quoted text, the authors suggest that at least five levels are needed for estimation of group-level, or among-population, variance . However, it is my observation that there is some confusion about this rule and it is often adhered to out of context, where authors or reviewers of ecological journals suggest that one cannot use random effects terms if they do not contain at least five levels ( Bain, Johnson & Jones, 2019 ; Bussmann & Burkhardt-Holm, 2020 ; Evans & Gawlik, 2020 ; Gomes & Goerlitz, 2020 ; Zhao, Johnson-Bice & Roth, 2021 ), although others are aware that this rule exists yet ignore it ( Latta et al, 2018 ; Fugère, Lostchuck & Chapman, 2020 ; Gomes, Appel & Barber, 2020 ; Allen et al, 2021 ). For context, within a small sample of the most recent articles in the journal Ecology ( N = 50), 18 articles mentioned 29 different random effects—only one of which (~3%) included fewer than five levels ( Fig.…”

Spatial and temporal distribution of bat mortality on a highway in southeast Brazil

“…However, these species have been most affected by collisions with vehicles on the roads (Pinheiro and Turci 2013; Ceron et al 2017;Valadão et al 2018;de Figueiredo Ramalho et al 2021). These species have been considered abundant in the study region (Dias and Peracchi 2008;Tavares et al 2010;Luz et al 2011), and have characteristics that make them good indicators of damaged areas, providing advantages for plants whose fruits are consumed by them, is a key factor for dispersion and genetic flow of plants in regions affected by fragmentation (Muller and This higher rate of collisions with frugivores bats is probably due to some associated factors, such as flight height, displacement patterns in foraging, the temporal and spatial distribution of the fruits and the plants, as well as the landscape structure (Bernard and Fenton 2003;Clevenger et al 2003;Bianconi et al 2006;Gumier-Costa and Sperber 2009;Pracucci et al 2012;Gomes et al 2020). An essential factor is that many of these frugivorous species are consumers of pioneer plants, which are usually found in large densities in degraded areas, such as the vicinity and edges of roads (Muller and dos Reis 1992;Reis et al 2003).…”

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

“…bilineata did not change the hourly activity between the extremes of brightness. This may relate with their foraging strategies (Gomes, Appel and Barber, 2020), as both species have been suggested to feed closer to vegetation in brighter nights (Jung and Kalko, 2010). The apparent absence of a moon effect on hourly activity of insectivorous bats was also found by Appel et al., (2017) in a continuous forest location in Central Amazonia and by Thomas and Jacobs (2013) in South Africa.…”