Action: Reduce management intensity on permanent grasslands for birds
- Four replicated trials and a review, of seven studies in total, found that some or all birds monitored were more abundant or foraged more on grasslands with lower management intensity than on conventionally managed agricultural grasslands.
- Four analyses from three replicated trials, of seven studies in total, found that some or all birds monitored were less or similarly abundant on grasslands with lower management intensity than on conventionally managed agricultural grasslands.
Reducing the intensity of grassland management involves one or more of: reducing or stopping the use of fertilisers, herbicides and pesticides; delaying the mowing date; reducing the number of cuttings taken.
Supporting evidence from individual studies
A replicated controlled, paired site study in the Netherlands (Kleijn et al. 2001) found that the density of breeding bird territories was not significantly different between 20 fields with meadow bird agreements and 20 control fields, both for all bird species and just for waders. Oystercatcher Haematopus ostralegus, black-tailed godwit Limosa limosa, common redshank Tringa totanus and lapwing Vanellus vanellus were all significantly less abundant on management agreement fields than on control fields. There was no significant difference in the number of territories between field types for three of these species, but oystercatchers had significantly fewer territories on management agreement fields than on control fields (0.13 vs. 0.52). Paired fields were within 1 km of each other, similar in size and soil type. Fertiliser inputs were significantly lower and mowing dates later on fields with management agreements than on conventionally managed fields. Birds were surveyed five times between March and June.
Further analysis of the same data used in Kleijn et al. 2001 (Kleijn et al. 2004), found that wading birds were less abundant on fields under meadow bird agreements (average of seven birds and 1.3 territories on agreement fields vs. 12 and 2.1 on conventional fields), whilst meadow songbirds were more abundant on meadow bird agreement fields, when analysed as a 12.5 ha scale (9.9 birds/plot on agreement fields vs. 7.7 on conventional fields). Duck and non-meadow bird breeding densities did not differ between management types at either the field, or 12.5 ha scale.
A 2006 replicated site comparison study of 42 fields in Switzerland (Kleijn et al. 2006) found that more birds, but not more bird breeding territories, were found in fields participating in the ecological compensation area scheme than in conventionally farmed fields. There was no difference in the numbers of bird species on each type of farmland. Ecological Compensation Areas are typically hay meadows farmed at low intensity: no fertilisers or pesticides (except for patch-wise control of problem weeds) are permitted, and vegetation must be cut and removed at least once a year - but not before 15 June (lowlands) or early July (mountains). The study surveyed seven pairs of fields (one within an Ecological Compensation Area, one conventionally farmed) and a 1-ha area surrounding each field, from each of three different parts of Switzerland four times during the breeding season.
A randomised, replicated, controlled trial on four farms in southwest England, in 2003-2006 (Defra 2007), found that 50 ´ 10 m plots of permanent pasture cut just once in May or July or not at all during the summer and left unfertilised attracted more insectivorous and seed-eating songbirds than control plots (fertilised plots cut in May and July, as in conventional silage management). The preference was shown by dunnocks Prunella modularis, winter wren Troglodytes troglodytes, European robin Erithacus rubecula, seed-eating finches and buntings, and was particularly strong for plots left uncut in summer. There were twelve replicates of each management type. This study is also discussed in ‘Reduce pesticide or herbicide use generally’, ‘Undersow spring cereals’, ‘Raise mowing height on grasslands’, ‘Reduce grazing intensity on permanent grasslands’ and ‘Plant wild bird seed or cover mixture’.
A replicated, controlled before-and-after study in 615 grassland fields in Jutland, Denmark (Kahlert et al. 2007), found that permanent grasslands fields under an agri-environment scheme designed to increase water levels had significantly higher numbers of three species of wader (northern lapwing Vanellus vanellus, black-tailed godwit Limosa limosa, common redshank Tringa totanus) in 2004-2005 after the scheme was implemented, compared to in 1999-2001, before the scheme. Eurasian oystercatchers Haematopus ostrolagus did not increase and effects varied between restored and permanent grasslands, and between wet and dry fields. The scheme involved promoting wet grasslands (see ‘Raise water levels in ditches or grassland’) as well as reducing fertiliser inputs, grazing pressure and the period of mowing.
A review of four experiments on the effects of agri-environment measures on livestock farms in the UK (Buckingham et al. 2010) found two replicated trials in southwest England showing that reduced management intensity on permanent grasslands benefits foraging birds. Both found higher numbers of invertebrates, seed heads and foraging birds at lower management intensity (less fertiliser, less cutting, less grazing or a combination of these). One study was the PEBIL project, also reported in Defra BD1444 (2007). The other was part of a Defra-funded project focussed largely on the effects of reduced grazing pressure (Defra report BD1454) for which no reference is given in the review. See ‘Reduce grazing intensity on permanent grasslands’ for more information.
A replicated site comparison study on farms in three English regions (Field et al. 2010) found that grassland managed under Higher or Entry Level Stewardship Schemes with low or very low inputs was not used significantly more by seed-eating farmland songbirds than improved grassland or open rough grassland. Between 0.5 and 2 birds/ha were recorded on average on the different types of grassland. The stewardship grassland category also included land being maintained as semi-natural grassland under the schemes. It is not clear how many sites of the different management types were used in the analysis. Surveys were done in the summers of 2008 and 2009 on 69 farms with Higher Level Stewardship in East Anglia, the West Midlands or the Cotswolds and on 31 farms across all three regions with no environmental stewardship.
- Kleijn D., Berendse F., Smit R. & Gilissen N. (2001) Agri-environment schemes do not effectively protect biodiversity in Dutch agricultural landscapes. Nature, 413, 723-725
- Kleijn D., Berendse F., Smit R., Gilissen N., Smit J., Brak B. & Groeneveld R. (2004) Ecological effectiveness of agri-environment schemes in different agricultural landscapes in The Netherlands. Conservation Biology, 18, 775-786
- Kleijn D., Baquero R.A., Clough Y., Diaz M., De Esteban J., Fernandez F., Gabriel D., Herzog F., Holzschuh A., Johl R., Knop E., Kruess A., Marshall E.J.P., Steffan-Dewenter I., Tscharntke T., Verhulst J., West T.M. & Yela J.L. (2006) Mixed biodiversity benefits of agri-environment schemes in five European countries. Ecology Letters, 9, 243-254
- Defra (2007) Potential for enhancing biodiversity on intensive livestock farms (PEBIL). Defra report.
- Kahlert J., Clausen P., Hounisen J. & Petersen I. (2007) Response of breeding waders to agri-environmental schemes may be obscured by effects of existing hydrology and farming history. Journal of Ornithology, 148, 287-293
- 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.
- Field R.H., Morris A.J., Grice P.V. & Cooke A.I. (2010) Evaluating the English Higher Level Stewardship scheme for farmland birds. Aspects of Applied Biology, 100, 59-68