Individual study: Wildflower areas within revitalized agricultural matrices boost small mammal populations but not breeding Barn Owls
Arlettaz R.L., Krähenbühl M., Almasi B., Roulin A. & Schaub M. (2010) Wildflower areas within revitalized agricultural matrices boost small mammal populations but not breeding Barn Owls. Journal of Ornithology, 151, 553-564
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Establish wild flower areas on farmland
A replicated, site comparison study in 2005 in four agricultural areas in Switzerland (Arlettaz et al. 2010) found that in most cases, following restoration, wildflower areas did not host more small mammal than nearby agricultural areas. In five of nine comparisons (between restored wildflower areas and wheat, maize and tobacco, over three sample seasons), there was no significant difference in the average abundance of small mammals in wildflower areas (458–1,285 animals/ha) and arable fields (34–682 animals/ha). In four of nine comparisons, small mammal abundance was significantly higher in restored wildflower areas (458–1,285 animals/ha) than in nearby arable fields (0–12 animals/ha). In four sites, live traps were placed in restored wildflower areas, wheat fields, maize fields, and tobacco fields. In each area, in May, July, and September 2005, three traps were placed every 5 m along two parallel 45-m-long transects, giving a total of 60 traps/area. Traps were operated over three nights and days at each area. Population sizes were estimated by mark-recapture techniques based on fur clipping of captured animals.
(Summarised by Phil Martin)
Plant nectar flower mixture/wildflower strips
A replicated study in 2005 in western Switzerland (Arlettaz et al. 2010) found that small mammal density and species richness were higher in wildflower areas than crops, but wildflower areas were avoided by barn owls Tyto alba. Wildflower areas (two years old, 1 ha) had more small mammal species and individuals (6 species, 458-1285 individuals/ha) compared to crops or meadows (2-5 species, 0-680/ha). In May and July, small mammal densities were significantly higher in wildflower areas (458-1,030 individuals/ha) and winter wheat Triticum aestivum (90-680/ha) than in tobacco Nicotiana tabacum, permanent and intensive meadows and in May maize Zea mays (0-10/ha) (in July the density in maize was 200/ha). In September, density was significantly higher in wildflower areas (1285/ha) than in winter wheat (0), other habitats had intermediate densities (5-60/ha). Barn owls significantly preferred cereal crops relative to availability and avoided wildflower areas and all other crop types. The estimated index of habitat selection by barn owls in order of decreasing preference was wheat, meadows, other crops and lastly wildflower areas. Four arable sites were studied. Small mammal population size was estimated using capture-mark-recapture. Mammal traps were placed at 20 points along two parallel 45 m transects in each habitat and set over three nights and days in May, July and September 2005. Seven breeding male barn owls were radio-tagged from June to September 2005 and hunting or resting locations recorded.