Far from home: bat activity and diversity in row crop agriculture
decreases with distance to potential roost habitat
Abstract
As demand for food increases, agricultural production is poised to
increase dramatically. Pesticides are commonly used to maintain high
crop yield, though they have several drawbacks, including reduced
efficacy over time and harmful effects to human and ecosystem health.
Bats are highly effective predators of crop pests and have great
potential to reduce crop damage resulting from insects. However, few
studies have investigated how pest control by bats might change over
large expanses of continuous row crop agriculture, which is common in
the Midwest. Agricultural landscapes offer few roosting opportunities
and could be difficult for bats to traverse, which might affect the
degree of ecosystem services provided by bats. We hypothesized that with
increasing distance into uninterrupted row crop agriculture 1) bat
activity would decrease and 2) bat species richness would decrease, but
that these effects would be buffered when insect pest abundance is high.
We deployed 50 acoustic bat detectors over 10 transects in east-central
Illinois from July to September 2021. In each transect, we placed
detectors on crop field edges at increasing distance from a large
riparian corridor assumed to be frequented by bats. Bat activity was
high across the landscape but declined by 56% from the forest edge to
4000m into row crop agriculture, while bat diversity decreased by 34%.
Pest abundance seemed to decrease overall bat activity but had no effect
on bat diversity. These results indicate that bats, although able to
have a large effect on crop pest reduction, might not be as efficient in
suppressing crop pests in vast uninterrupted agricultural landscapes
which offer scant roost availability. Our work will inform
recommendations to landowners and private lands managers on ways to
increase bat access to roosts and forest cover near agricultural areas,
thereby enhancing the potential for bats to provide pest control
services.