Action: Raise mowing height on grasslands to benefit birds
- A review from the UK found that raising mowing height may have increased productivity of Eurasian skylarks, but not sufficiently to maintain the local population.
- A randomised, replicated and controlled study from the UK found that no more foraging birds were attracted to plots with raised mowing heights, compared to plots with shorter grass.
Vegetation height is important in determining the value of a grassland to wildlife. High vegetation can provide more complex environments and more habitats, but short vegetation can allow birds access to the ground which can help foraging, and can reduce the risk of predation (see Provide short grass for waders).
Supporting evidence from individual studies
A randomised, replicated, controlled trial on four farms in southwest England in 2003-6 (Defra 2007) found that 12, 50 ´ 10 m plots of permanent pasture cut to 10 cm in May and July did not attract more foraging birds than 12 control plots cut to 5 cm. Plots were cut twice in May and July, and grazed in autumn/winter. This study is also discussed in ‘Reduce management intensity on permanent grassland’, ‘Reduce pesticide or herbicide use generally’, ‘Undersow spring cereals’, ‘Reduce grazing intensity on permanent grasslands’ and ‘Plant wild bird seed or cover mixture’ .
A review of four experiments on the effects of agri-environment measures on livestock farms in the UK (Buckingham et al. 2010) found one trial from 2006 to 2008 that tested the effect of mowing height on skylarks Alauda arvensis nesting in silage fields. Preliminary results showed that chick survival was not affected by raised cutting height. However, the number of new birds produced each year (productivity) was more sensitive to re-nesting rates than chick survival. Raised cutting height slightly increased productivity, because skylarks re-nested sooner after cutting, but this was not enough to maintain a local population given survival rates. This study formed part of a Defra-funded project (BD1454) for which no reference is given in the review.
- Defra (2007) Potential for enhancing biodiversity on intensive livestock farms (PEBIL). Defra report.
- Buckingham D.L, Atkinson P.W., Peel S. & Peach W. (2010) New conservation measures for birds on grassland and livestock farms. Proceedings of the Lowland Farmland Birds III: delivering solutions in an uncertain world, 60.