Field evaluation of the potential for avian exposure to clothianidin following the planting of clothianidin-treated corn seed

This objective of this study was to quantify consumption of clothianidin-treated corn seed by birds following standard planting practices. Post-planting seed counts on 21 fields in southwestern Ontario, Canada, demonstrated that a small proportion of total sown treated seeds remained on the soil surface immediately post-planting (i.e. mean 0.3 ±0.2% of the total sown seeds). Behavior monitoring of individual birds and 24-hr remote video surveillance were deployed to investigate how much of the treated seed remaining on the soil surface was consumed by birds. Spotting scopes were used to monitor the full duration of the field visits of 596 individual birds during morning hours for three consecutive days after planting on each of the 21 fields. Only two birds were observed consuming treated seeds (one seed each) and three birds consumed seeds for which the treatment status could not be visually confirmed. Similarly, in > 1,380 hours of continuous video monitoring of field locations with the highest likelihood of avian exposure (where multiple treated seeds remained clustered on the soil surface), no birds were observed eating treated seed. This study provides field verification on two factors that determine exposure: 1) standard sowing practices in Ontario are effective at burying treated seeds such that the count of seeds on the soil surface after planting is low, and 2) foraging birds monitored on these fields consumed very few of the clothianidin-treated corn seeds remaining on the soil surface after planting.