Researchers at the University of Stirling have found that agri-environment schemes, commonly introduced by farmers to counter the negative effects of intensive agriculture on biodiversity, are associated with lower levels of bat activity and reduced numbers of key insect prey.
Bats comprise a third of all UK mammals, but their populations have declined dramatically over the past century. They are important in the environment as nature’s best pest control system: in a single night one pipistrelle bat can eat up to 3000 insects.
Elisa Fuentes-Montemayor, of the School of Natural Sciences, explained: “Farmers are paid to adopt environmentally-sensitive agricultural practices, such as the leaving field margins unsprayed or cropped, planting species-rich grassland and maintaining hedgerows. There has been very little evaluation of these schemes in Scotland and nobody had ever assessed whether bats benefit from such measures.”
In the first ever assessment of agri-environment schemes in the UK in relation to bats, researchers surveyed bat activity on farms in central Scotland - with and without AES in place - and somewhat surprisingly found that farms within AES actually had less pipistrelle bat activity than those who were not in schemes.
The most important factor that was positively associated with bat activity was the amount of woodland in the surrounding landscape. Ms Fuentes-Montemayor noted that “Whilst there are financial schemes to create woodlands on agricultural land, we need to know how to maximise their effectiveness in terms of spatial configuration and management.” Work assessing the effectiveness of farm woodland schemes for bats and nocturnal insects is currently underway at the University of Stirling.
Highlights ► Four commonly applied schemes were assessed: species rich grassland, hedgerows, water margins and field margins. ► Activity of pipistrelle bats and the abundance of key insect groups were lower (by 40–50%) on farms participating in AES than on non-participating farms. ► Key insect prey abundance was lower at specific AES management prescriptions than at equivalent conventionally-managed features. ► These findings are in contrast to studies of some other animal groups (e.g. bumblebees, hoverflies, butterflies and moths) which have shown positive responses to AES implementation. It is possible that these AES could potentially benefit bat species that feed predominantly on moths but this is yet to be tested. ► This work was funded by a graduate scholarship from the Mexican Government (CONACyT) the People’s Trust for Endangered Species.
Pipistrelle bats and their prey do not benefit from four widely applied agri-environment management prescriptions is published in Biological Conservation, Volume 144, Issue 9, September 2011, Pages 2233-2246. The full paper can be found at: www.sciencedirect.com/science/article/pii/S0006320711002254