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Seed treatments are widely used for crop protection and present a particular risk to granivorous birds. UK risk assessment for seed treatments has tended to focus on highly granivorous species; however, under some conditions, non-granivorous birds will take seeds. Better data is needed on which species eat seeds for which pesticide treatments are used. To identify which species will take and eat a range of crop seeds in common usage in the UK, birds visiting bait stations at which untreated seed was presented were video recorded. Information was also obtained on how much seed is taken by individual birds. The seeds tested were wheat, barley, maize, oilseed rape, grass, peas and pelleted sugar beet. For many of the species observed at the bait stations, the amounts of seed consumed during single visits were sufficient to pose a potential risk (toxicity-exposure ratio < 10) if the seed had been treated with one of the more acutely toxic seed treatments. Previous studies have shown that de-husking of seeds can substantially reduce birds' exposure. This paper provides information on which of the species recorded de-husked which seeds, in field conditions. The use of these data in pesticide risk assessment is considered.

Summary 0[ Pesticides applied to seeds before sowing may present a high risk to seed!eating birds[ Some of these chemicals are highly toxic but are avoided by captive birds in laboratory tests[ However\ evidence for birds avoiding them in the _eld is lacking[ The objective of this study is to investigate avoidance and other factors a}ecting risk of poisoning\ using the model of wood!pigeons Columba palumbus L[ feeding on winter!drilled cereal seed treated with the organophosphorus insecticide fonofos[ 1[ Wood!pigeons feeding on arable _elds in Cambridgeshire\ UK\ were counted once or twice per week over four winters from 0881 to 0885[ In autumn\ newly drilled cereal _elds are shown to be preferred to alternative crops such as stubble and ploughed _elds and root crops[ In spring\ newly drilled cereal _elds are sometimes preferred to older cereal _elds\ stubble\ ploughed _elds and drilled onions[ 2[ Fewer _elds drilled with fonofos!treated cereal seed were used by wood!pigeons than untreated "without fonofos# _elds for the _rst week after drilling only[ The extent of the avoidance reaction was related to the concentration of fonofos on the seed left exposed on _eld surfaces[ 3[ The concentration of fonofos on newly drilled seed exposed on _eld surfaces "mean of 130 mg kg Ð0 # was much lower than expected from the approved application rate "0979 mg kg Ð0 #[ Residues decayed linearly at a rate of 1) per day after drilling and varied widely between _elds[ 4[ The density of seed left exposed after drilling also varied widely between _elds\ being greater on headlands "_eld edges# than the main _eld and declining at a rate of 1) per day after drilling[ 5[ Of 50 wood!pigeons shot within the study area over three winters\ 15 had been feeding on cereal seed and of these\ six contained fonofos residues at levels similar to poisoned birds submitted to the MAFF Wildlife Incident Investigation Scheme[ 6[ In conclusion\ fonofos!treated cereal seed may be partially avoided in the wild[ Avoidance fails to prevent poisoning under some "rare# conditions\ possibly when seed density\ concentrations of fonofos and levels of hunger are all above average[ The implications for risk assessment are discussed[ Key!words] _eld selection\ pesticide residues\ repellency\ risk assessment\ wildlife poisoning[ Journal of Applied Ecology "0888# 25\ 172Ð185

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