barn owls

We monitored 16 radio-tagged moreporks (Ninox novaeseelandiae) on Mokoia Island after a brodifacoum poison drop to eradicate mice (Mus musculus), normally included in the owls' diet. All 16 moreporks were alive after 13 days. One bird was found dead on day 22, and corpses of two radio-tagged birds were located on day 51. The bird found on day 22 contained 0.97 mg kg(-1) of brodifacoum in its liver. The other two carcasses were not analysed, but they probably died as a result of brodifacoum poisoning. Thus, three out of 14 birds died (21% mortality).

In Britain, the use of "second-generation'' rodenticides has become widespread on agricultural premises. The high toxicity and relatively long half-lives of these compounds has raised concerns over potential secondary exposure and poisoning of non-target predators. Over the last 15 years, exposure has been extensively documented in the barn owl Tyto alba but relatively little is known about mammalian terrestrial predators.