Landscape features drive insectivorous bat activity in Indian rice fields

Abstract

ContextThe conversion of natural land for agriculture is a crippling threat to biodiversity. The effect of this conversion can be minimised by understanding the habitat requirements of local species and incorporating them into agricultural landscapes. Insectivorous bats, which have been shown to control a number of agricultural insect pests, exhibit species-specific responses to the surrounding landscape, tied closely to their morphology and foraging mode. The activity and distribution patterns of bats are therefore influenced by the landscape characteristics. ObjectivesThis study aimed to determine which features in the landscape surrounding rice fields influence the activity levels of insectivorous bats, and at what scales they were most influential.MethodsWe collected acoustic recordings to determine activity levels of seven bat sonotypes in rice fields surrounded by a variety of landcover types in the Nagaon district of Assam, India. Using this, we determined the most important set of features in the surrounding landscape, and the scales at which they were most predictive, for each sonotype. ResultsOur results suggest that variables related to tree cover are the most important predictors of bat activity in rice fields. Distance to nearest forest, area of forest within 1km, distance to nearest forest edge, and landscape heterogeneity influenced all five of the analysed bat sonotypes. Also important were the amount of urban land within 1km, which exerted a negative effect on the activity of one sonotype, and moonlight activity, which negatively influenced the activity levels of one sonotype. ConclusionOur results demonstrate that when in rice fields, bat activity is most influenced by presence and proximity of trees. Increasing tree cover in agricultural landscapes will increase bat activity and likely the level of pest control.