The effect of crop, cultivation and seed addition for birds on surface weed seed densities in arable crops during winter

Provide supplementary food for birds or mammals

A replicated controlled trial in 1999-2002 on arable fields on three farms in Hampshire, Lincolnshire and Yorkshire, UK (Holland et al. 2008) investigated whether addition of supplementary bird seed affected the abundance of weed seeds on the soil surface by attracting seed-eating birds. The study found no difference in mid-winter weed seed densities in sites with and without addition of bird seed, even though a separate study at the same site recorded more birds on areas with added seed. This may have been due to low winter seed predation by birds. Post-treatment winter seed densities varied from 151 to 398 seeds/m² on control plots and 92 to 365 seeds/m² on treatment blocks. There was some evidence that birds changed the species composition of weed seeds, as there were fewer larger-sized weed seeds in treatment blocks. Bird seed (36 kg/ha, 444 seeds/m², including cracked maize and linseed/soya/barley or sorghum/millet) was applied three times from November-March on two 100 ha blocks, with a further two control blocks, on each farm. Seed densities were estimated from 10 soil scrapes (0.2 x 0.2 m), from at least 10 field edge and 10 mid-field locations in each block, before the first bird seed application and 2-3 weeks after each application.