Effects of agroecosystems on insect and insectivorous bat activity:a preliminary finding based on light trap and mist net captures

Abstract

IntroductionInsectivorous bats constitute about 70% of all bats and are characterized by generally using echolocation to detect prey items (Simmons and Conway, 2003). Nearly all insectfeeding bats are nocturnal (Speakman, 1995), occupy a diversity of habitat types, and exploit a wide variety of prey (Altringham, 1996;Kalko et al., 1996). Some authors have suggested that insect prey abundance influences the local occurrence of insectivorous bats (Rautenbach et al., 1996;Pavey et al., 2001). In other words, changes in the activity level of insects may influence the foraging behavior and activity levels of the bats. Hence, insectivorous bats time their foraging flight patterns to coincide with maximum nocturnal activity of their prey.Abiotic factors such as light, temperature (Russ et al., 2003;Barros et al., 2014), and wind speed (Russo and Jones, 2003;Johnson et al., 2011) exhibit high diurnal fluctuations and are thus likely to influence predator (bats) and prey (insects) activities directly or indirectly. The activity patterns of many nocturnal animals comprise trade-offs between prey availability and predation risk, which are likely to be modulated by light conditions in connection with the lunar cycle. Some studies have shown that moonlight decreases nocturnal activity in animals, including birds (Nelson, 1989), insects (Williams et al., 1956), and rodents (Clarke, 1983). This reduction in activity during periods of high lunar illumination is assumed to hold true for many other bat species (Erkert, 1974(Erkert, , 1978. In addition, Saldaña-Vásquez and Munguía-Rosas (2013) reported that the negative effect of moonlight on tropical bats is higher than on temperate species.According to Findley (1993) and Humphrey (1975), areas that offer a variety of trees and roosts often support the largest numbers of bat species and individuals. In recent years, croplands, plantations, and pastures have significantly expanded globally (Foley et al., 2005). Transformations of land-use types (e.g., forests) via anthropogenic activities are the major drivers behind species loss regionally and globally, through habitat destruction and modification. One such driver that occurs on a global scale is agricultural intensification. This system of farming, which is characterized by high tillage operations, synthetic fertilizers, and pesticide (i.e. agrochemicals) use, is accompanied by loss of

Little evidence of a road‐effect zone for nocturnal, flying insects

“…To account for nightly variation in environmental conditions, we included daily minimum temperature (T) and moon phase (M, 3 categories: new moon, full moon, first/last quarter). New moon was used as the reference; more nocturnal flying insects tend to be trapped during moonless nights, compared to full moon or partial moon nights (Lawer & Darkoh, 2016;Nowinszky, Puskas, & Kuti, 2010). To account for site-level variation, we included several measures of vegetation structure, within a 10 m radius of the light trap: richness of tree and shrub species (number of different tree and shrub species in a 10 m radius, S); number of large trees (diameter > 30 cm at breast height, N); and canopy cover (C) (Ober & Hayes, 2008 (Su & Yajima, 2015).…”

Echolocation and Stratum Preference: Key Trait Correlates of Vulnerability of Insectivorous Bats to Tropical Forest Fragmentation

“…Farneda et al (2015) showed that diet type is an important predictor of vulnerability to fragmentation in phyllostomids, and this may also be true for AIB. In fact, insectivorous bats have distinct diets that include a broad diversity of insect groups or adjust their activity patterns to new environmental conditions (Kalka and Kalko, 2006;Lawer and Darkoh, 2016;Kemp et al, 2019;Rocha et al, 2019) and there is evidence that some of these are substantially impacted by forest fragmentation (Didham et al, 1996;Golden and Crist, 1999;Rösch et al, 2013;Benítez-Malvido et al, 2016). Diet type may thus influence the vulnerability of AIB to fragmentation, but we could not include this trait in our study due to the scarcity of knowledge about the diet of the species involved.…”

Calculation of biodiversity level between different land-uses to improve conservation outcomes of biodiversity offsetting

“…In our study, hedgerow appeared to support the highest biodiversity level we considered, whatever the scenario was, comparing to fallow, grass strip or grass strip with bushes or one bush. Those results could be used in another context than biodiversity offsetting and complete the literature available on the agri-environment context (see for example Lawer and Darkoh, 2016;Pe'Er et al, 2017;Robleño et al, 2017).…”