Natural vegetation and bug abundance promote insectivorous bat activity in macadamia orchards, South Africa

Abstract

Accelerating land use change is associated with the loss of species and their ecosystem services. South Africa is the world's largest producer of macadamias and the industry continues to grow. Insectivorous bat species are important for pest control, but bat populations are declining. Therefore, proactive management of bat communities in agricultural landscapes is essential. We acoustically monitored bats and used light traps to catch arthropods during one annual cycle, sampling five macadamia orchards monthly in Limpopo, South Africa. We used GIS and R to analyse both the general bat and foraging bat activity of the two main foraging guilds (open-air/ clutter edge guild) in different land use types and total activity with respect to arthropod abundances. Overall clutter edge guild activity (number of passes) decreased with macadamia and orchard (all other fruit) cover in the high season and increased with bush cover and distance to settlements (potential roosts) in the low season. Open-air guild activity increased with fallow cover in the high season. Foraging activity (feeding buzzes) of the clutter edge guild increased with bush cover over the whole year. Total activity (both guilds) increased with abundance of true bugs, including the main macadamia pests, and bush cover. In conclusion, natural and semi-natural vegetation promote bat activity in macadamia orchards, and potentially bats' provision of the ecosystem service of pest control. In times of accelerating land use change, remnants of natural vegetation are important refuges and need to be maintained or restored. The installation of bathouses might further improve bat activity.