Action: Plant more than one crop per field (intercropping)
A study from the USA found that 35 species of bird used fields with intercropping, with four nesting, but that productivity from the fields was very low.
Planting more than one crop in each field increases habitat heterogeneity at a smaller scale than increasing crop diversity at a landscape scale (see ‘Increase crop diversity’). Heterogeneity is thought to be key for increasing farmland biodiversity and so planting multiple crops may help birds of different functional groups to use a single field.
Supporting evidence from individual studies
A study on two arable farms in Iowa, USA, in May-August 1992-3 (Stallman & Best 1996), found that 35 bird species used fields under an experimental intercropping system, with an average of 108 birds/count/100 ha. Three native species (red-winged blackbird Agelaius phoeniceus, common grackle Quiscalus quiscula and vesper sparrow Pooecetes gramineus) nested in the fields, but that only one nest of forty (2.5%) successfully fledged young. Destruction by farming activities was the largest cause of nest mortality (39%) followed by predation (29%). Desertion only occurred at 5% of nests. Strips were 4.6 m wide and contained corn, soybeans and oats as well as mammoth red clover Trifolium pratense.