Bats respond negatively to increases in the amount and homogenization of agricultural land cover
Abstract from paper: Changes in agricultural landscapes due to intensification, such as loss of natural areas, loss of grazing lands to annual row crops, and increased use of pesticides, have led to widespread declines in biodiversity. Bats are expected to respond negatively to agricultural intensification because of reductions in prey abundance and roosting habitat availability. We measured relative bat abundance with acoustic bat recorders in landscapes that varied in (1) the proportion of agriculture and (2) the proportion of agriculture that is in annual row crops vs. perennial forages (pasture and hay). We predicted that relative bat abundance would be highest where (1) the proportion of agriculture was low and (2) the agriculture was dominated by perennial forage. Consistent with our first prediction, the abundance or presence of four bat species, total bat abundance and bat species richness declined with increasing agricultural cover. Counter to our second prediction, we did not find a negative relationship between species richness or relative bat abundance or presence and the proportion of agricultural land that is in annual row crops. Instead we found that the abundance of three bat species, total bat abundance and bat species richness were greatest where the proportion of agriculture in annual crops was about equal to the proportion in perennial forage. Based on these results, we suggest that bat abundance and richness can be increased in agricultural landscapes by reducing the conversion of natural areas to agriculture and by maintaining a balance of perennial forage and annual crop agricultural cover types.