Quantifying Frequency & Effects of Secondary Exposure to Rodenticides in Barn Owls

Birds of prey offer natural pest control services in human dominated landscapes, especially on farms, where recruiting raptors is often a key commponent of sustainable agriculture. Barn owls (Tyto alba) are often recruited to nest boxes installed by growers as part of an integrated pest management framework. However, application of anticoagulant rodenticides is also a component of farming operations, which may limmit the contributions provided by raptors due to secondary rodenticide poisoning. 

A team comprised of UC Davis graduate students, Ryan Bourbour, Breanna Martinico, and Emily Phillips, and Dr. Joshua Hull in collaboration with Dr. Sara Kross from Sacramento State, are investigating the prevalence of rodenticide exposure and non-lethal effects in adult and nestling barn owls in agricultural settings. They are documenting nestling development in relation to rodenticide exposure levels, tracking movement of breedgin adults, and documenting prey items delivered to nests in relation to crop type and rodcenticide applications. Additionally, they are monitoring rodenticide exposure in wintering raptor populations of barn owls and red-tailed hawks (Buteo jamaicensis) to see how exposure levels differ across seasons, age, and between diurnal and nocturnal raptor species. 

Their goal is to create a complete picture of raptors and rodenticide application in industrial agriculture in order to make recommendations to enhance natural pest control services provided by raptors and reduce secondary poisoning from rodenticides based on sound science.