Retain unmown field margins
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Field margins can provide foraging habitat for bats. Leaving field margins unmown and allowing them to regenerate naturally can increase the abundance and diversity of plants and invertebrate prey. See also ‘Plant field margins with a diverse mix of plant species’. For studies that may carry out this intervention alongside other interventions to benefit bats on farmland, see ‘Introduce agri-environment schemes’.
Supporting evidence from individual studies
A replicated, paired sites study in 2008 on 15 pairs of farms in Scotland, UK (Fuentes-Montemayor et al 2011) found that unmown field margins on agri-environment scheme farms had similar activity of Pipistrellus species as field margins on conventional farms. The activity of common pipistrelles Pipistrellus pipistrellus and soprano pipistrelles Pipistrellus pygmaeus was similar along unmown and conventionally managed field margins (data reported as statistical model results). On agri-environment scheme farms, field margins were planted with a mix of grass seeds and had restrictions on fertiliser, pesticides and grazing. Each of 15 field margins on agri-environment scheme farms was paired with 15 field margins on conventional farms with similar farming activities and surrounding habitats. Field margins (measured on five pairs of farms) were wider and had taller vegetation on agri-environment scheme farms (average 6 m wide, 2.4 m tall) than conventional farms (average 2 m wide, 2 m tall). Each of 15 pairs of farms was sampled once on the same night in June–September 2008. Bat activity was recorded along transects (2.5–3.7 km long) from 45 minutes after sunset using bat detectors.Study and other actions tested