DOCHY O (2013) Triple-strip field margins for farmland birds: the 'Big Three' in one scheme. LIMOSA 86 (3): 180-191.

Triple-strip field margins are conservation margins on arable farmland with a differentiated mowing regime in three parallel strips. One strip is not mown and provides cover all year round. The two others are mown together in early spring to get a short sward, and thereafter alternatingly each month until summer. They are sown with a mixture of indigenous grasses and herbs. In addition to cover and a short open sward, these strips also host many insects attracted by the flowers and the indigenous host plants, while the seeds provide winter bird food. During a three-year project in the polder area of western Belgium, 4 km of 12 - 18 m wide margins of this kind were sown. These areas were compared with classical single-strip margins, sown with ryegrass Lolium sp. only, and with fields without conservation field margins.
      Breeding birds were counted by territory mapping. Due to large variation in bird densities in different parts of the study area and a small number of repeats (2-3), we found no significant differences between the management types, except for from Meadow Pipit which preferred single-strip margins. Grey Partridges did shift their territories to the triple-strip margins, but the dataset is too small to draw firm conclusions. In summer, the strips were heaving with insects, attracted by the flowers in the mixture. This was not seen in single-strip margins nor in road verges. This may enhance field margin ecosystem services like pollination and natural pest control.
      Wintering birds were counted by line transects along field edges. Triple-strip field margins were used more often than expected on the basis of availability by Skylark, Meadow Pipit, Reed Bunting and Stock Dove. Single-strip margins were preferred by Meadow Pipit an Skylark, Common Starling and Grey Partridge. Grey Partridges occurred mostly near farmsteads outside the count perimeters. Hares were not counted but frequently observed in the triple-strip field margins, throughout the year.
      The recipe of the mowing regime clearly delivers all three of 'the Big Three' needs for farmland birds, i.e. cover, insects and seeds. Moreover, the sward stayed fairly open for at least four years and the flowering season was extended. As we did not find a clear effect on bird populations, one may conclude that triple-strip field margins in a density of less than 5% of the area might be too scarce to induce real advantages for farmland birds. Further research should focus on a trial with higher densities of these margins and should look at their use by individual birds. The question whether nests are destroyed by mowing of part of the triple-strips is also relevant.

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