Mitigating the impacts of agriculture on biodiversity: bats and their potential role as bioindicators

1 Agriculture is a dominant land use worldwide with approximately 40% of the land's surface used for 2 farming. In many countries, particularly parts of Europe, this figure is substantially higher and most 3 agricultural land is under intensive practices aimed at maximising the production of food. The 4 intensification and expansion of modern agricultural practices led to the biological simplification of 5 the farmed environment, which has resulted in declines in farmland biodiversity during the last 6 century. As with other taxa, many bat species have suffered severe population declines during the 7 20th century, with agriculture believed to be one of the main drivers reducing roost availability and 8 foraging habitat. Lower intensity farming methods, and the creation or management of habitat features 9 on farmland could potentially mitigate some of these negative impacts but the effects of this on bats, 10 in comparison to other taxa, have received relatively little attention. Here, I review evidence on the 11 impacts of efforts to increase biodiversity in agricultural landscapes on bat populations, and explore 12 whether responses of bats to agricultural activities are similar to those of other taxa, a necessary 13 requirement if they are to be used as bioindicator species. 14 The review revealed that there are relatively few studies with which to assess the effects of 15 management interventions on bats in agricultural landscapes, and these are restricted to only a few 16 countries. Nevertheless, there is evidence that bats benefit from lower intensity agricultural systems, 17 specifically organic farming and shaded agroforestry: these systems tend to be associated with higher 18 bat abundance, species richness and diversity, and are more heavily utilised by foraging bats. Whilst 19 very few studies have explicitly tested the utility of bats as bioindicators in agricultural landscapes, 20 overall, the response of bats to lower intensity agricultural systems also reflect responses by other 21 taxa. These studies have been largely restricted to temperate regions, however. The review highlights 22 several major gaps in our knowledge of bats in agricultural landscapes and where future research 23 could be usefully directed including: 1) a broader geographical range of studies examining both the 24 efficacy, and the underlying mechanisms through which lower intensity agricultural systems may 25 benefit bats; 2) the potential for lower intensity systems in key crops such as oil-palm; 3) studies of 26 the demographic effects of conservation management on …