Exposure to Anticoagulant Rodenticides in American Kestrels (Falco sparverius) in Kentucky, 2014–2018

Anticoagulant rodenticides (ARs) are commonly used across the US to control rodent populations but may cause negative effects when secondarily consumed by raptors. Falco sparverius (American Kestrel) is a species of growing conservation concern due to widespread declines. We investigated AR exposure in American Kestrels by testing liver samples from 23 carcasses salvaged in Kentucky during 2014–2018. We confirmed exposure to 1 or more AR compounds in 57% of the birds examined. Rodenticides detected included brodifacoum, bromadiolone, and diphacinone. Brodifacoum was the most commonly detected AR, found in 92% of AR-positive birds. AR exposure was disparate among nestlings from 2 nests. None of the American Kestrels were diagnosed with AR toxicosis, but we found a significant association between poor nutritional condition and AR exposure. Our results indicate that secondary exposure to ARs in American Kestrels warrants more study as a potential contributor to population declines.