The importance of natural habitats to Brazilian free-tailed bats in intensive agricultural landscapes in the Winter Garden region of Texas, United States

Abstract

a b s t r a c tThe conversion of natural lands to agriculture is a leading cause of the worldwide loss of biodiversity. In particular, cropland monocultures alter insect abundance and diversity compared to adjacent natural habitats. While agricultural lands can provide large numbers of insect pests as prey items to predators such as bats, insect pest population size vary greatly throughout growing seasons. This study assesses the importance of land use and corn earworm moth availability as spatial and temporal drivers of bat activity. We quantified spatial variation in land use patterns at fifteen sites located within the Winter Garden region in south central Texas and used bat detectors and insect pheromone traps to monitor nightly bat activity and corn earworm moth abundance across the landscape and throughout most of the year. Our temporal analyses show that bat activity was positively correlated with moth abundance, but only early in the growing season when moth abundance is at its peak. The key result from this study is a positive relationship between bat activity and natural habitat cover during late summer months, corresponding to periods of low moth abundance and a peak in bat activity. During the late summer period, bats were more active at sites containing a larger percentage of natural habitats than those containing a larger percentage of agricultural land. Our results strongly suggest that intensive agricultural practices create systems providing bats with inconsistent resource supply, but the persistence of natural habitats provides consistency in food supply though time. Taken together, these findings illustrate the importance of protecting and restoring natural habitats for the conservation for bats and the pest-suppression services they provide in agricultural ecosystems.

Acoustic lure allows for capture of a high‐flying, endangered bat

“…Worldwide, molossids constitute a very small fraction (often <1%) of total mist‐net captures (Ammerman et al ), despite documentation of colonies consisting of millions of individuals (e.g., Brazilian free‐tailed bats [ Tadarida brasiliensis ]; Betke et al ). Thus, many studies of molossids rely instead upon counts and captures at roost sites (Hristov et al , Noer et al ) or acoustic surveys (Davidai et al , Deshpande and Kelkar ).…”

Investigating Bat Activity in Various Agricultural Landscapes in Northeastern United States

“…Agricultural practices such as organic farming that promote more crop and ecosystem biodiversity and do not utilize agro-chemicals can support bat foraging [19]. Farms that can provide natural areas provide both habitat and consistent food source for bats [20]. Landscape diversity that provides forests, open foraging, and riparian areas can support multiple bat species and their preferred habitats [21] and riparian buffers are incorporated into many bat conservation plans [15].…”

Effects of Organic Farming and Agricultural Landscape Composition on Relative Bat Diversity and Abundance

“…After visually inspecting the plots between the proportion of agriculture in annual crops and the bat response variables we noticed that some relationships had a quadraticshaped pattern. Since different nocturnal aerial insects can be pests of particular crop types (Davidai et al 2015), landscapes with a greater number of crop types may have greater availability of bat prey throughout the season. With few types of crops commonly planted in our study area (OMAFRA 2017), a landscape with a mixture of perennial forages and annual row crops would have high Shannon diversity of crops at small spatial scales (Appendix 1.D).…”

“…in Texas (Davidai et al 2015). With higher insect diversity in perennial forage fields (Werling et al 2014), there is more stability in insect populations through the season.…”

“…A greater variety of vegetation in a field should support more insect diversity (Knops et al 1999), because of the availability of more varied habitats (Tews et al 2004). Insectivorous bats should benefit from greater insect diversity, as higher diversity should provide a more stable level of prey availability throughout a night because different insect species can be active at different times during the night (Rydell et al 1996), and throughout a season (Davidai et al 2015). Natural areas might also provide more roosting habitat (trees) than agricultural areas, particularly for bat species that do not roost in human-made structures such as houses.…”