| FARMLAND ECOLOGY - HABITATS FOR BATS
Bats and agri-environment schemes Setting up a detector in the field to monitor bats. © Niamh McHugh/GWCT
BACKGROUND Several European bat species declined during the 20th century owing to many factors including the loss of roost and feeding sites through agricultural intensification. Bat roosts in England are protected by law, but feeding sites are not, making them susceptible to land use change. English agri-environment schemes (AES) represent approximately 14% of agricultural land in the UK and, although they do not specifically target mammals, many are designed to increase invertebrate food resources. They may therefore represent important local foraging patches for bats.
16 | GAME & WILDLIFE REVIEW 2019
Across Europe agri-environment schemes (AES) have been introduced which attempt to counteract biodiversity losses relating to agricultural intensification. However, the potential benefits of AES to non-target groups such as bats are unclear. The AgriBats project aimed to determine how AES habitats are used and can be best managed to benefit a range of bat species. In our study, we assessed how the vegetative characteristics of four commonly employed AES habitat types (grass margins, wildflower margins, wild bird seed mixture plots and pollen and nectar plots) influenced the occurrence and activity of bats. Surveys were conducted on 48 AES habitat plots across 15 farms. Each plot was surveyed for nine nights between 12 April and 1 September 2017 using passive real-time bat detectors, resulting in 432 nights of recordings being collected over the project. After data checking 9,154 recordings of bats were available for analysis representing six species and a further two bat genera (see Table 1). Common pipistrelle were recorded most frequently accounting for 71% of recordings, soprano pipistrelle and barbastelle were also recorded relatively frequently, representing 10% and 6% of recordings respectively. Therefore, in this summary, we focus on relationships between these three bat species and AES. The vegetative characteristics of AES habitats were assessed in five 0.5-m² quadrats, spaced 10 metres (m) apart, centred around the bat detector. Grass, broad-leaved plant and bare ground coverage was estimated in each quadrat, and counts of the number of ground flora species and the number of individual flowering plants present within quadrats were made. The adjacent field boundary height was estimated to the nearest 0.5m and averaged across five points. The number of trees present was also counted and distance measured to the nearest woodland, as the crow flies. The importance of AES vegetation characteristics varied between bat species. Cover of flowering plants was positively correlated with the occurrence of common pipistrelle. Soprano pipistrelle and barbastelle activity increased with plant diversity within plots, and barbastelle activity showed a further positive correlation with flowering plant abundance. Common pipistrelle was most influenced by field boundary features and its activity was positively correlated with boundary height and the number of trees present. Barbastelle activity was also positively related to boundary
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