Prevalence of Anticoagulant Rodenticides in Feces of Wild Red Foxes (Vulpes Vulpes) in Norway

Abstract

High occurrence of anticoagulant rodenticides (ARs) in wildlife is a rising concern, with numerous reports of secondary exposure through predation. Because of widespread distribution of the red fox (Vulpes vulpes), they may act as sentinels for small mammal-hunting predators in rural, suburban, and urban areas. No AR surveillance in wild mammals with analyses of residues in feces has been conducted throughout a single country. We collected 163 fecal samples from presumed healthy red foxes from 18 out of 19 counties in Norway. The foxes were shot during regular hunting between January and December 2016 and samples collected directly after death. Fecal samples were analyzed for six ARs: brodifacoum, bromadiolone, coumatetralyl, difenacoum, difethialone, and flocoumafen. We detected ARs in 54% (75/139) of the animals. Brodifacoum was most frequently detected (46%; 64/139), followed by coumatetralyl (17%; 23/139), bromadiolone (16%; 22/139), difenacoum (5%; 7/139), difethialone (1%; 2/139), and flocoumafen (1%; 2/139). More than one substance was detected in 40% (30/75) of the positive foxes, and 7% (5/75) of these animals were exposed to four different ARs. There were no statistically significant seasonal, age, or sex differences in foxes after exposure to one AR compound. We found a significant difference in occurrence of brodifacoum and coumatetralyl in foxes from different geographical areas. These findings demonstrate fecal analyses as a valuable method of detecting AR exposure in red foxes. We suggest using direct fecal sampling with analyses as a method to evaluate the occurrence of ARs in live endangered wildlife in connection with radio tagging or collaring operations.

Micro QuEChERS-based method for the simultaneous biomonitoring in whole blood of 360 toxicologically relevant pollutants for wildlife

“…Although the penetration of rodenticides into the trophic chain is a known fact (Plaza et al, 2019;Ruiz-Suarez et al, 2014;Sanchez-Barbudo et al, 2012;Seljetun et al, 2019), it is still surprising that residues of at least one of these compounds have been found in almost 15% of the birds in this series. More than one compound was found in 8 of the individuals (from 2 to 4 compounds).…”

Intensive livestock farming as a major determinant of the exposure to anticoagulant rodenticides in raptors of the Canary Islands (Spain)

“…This threat was dramatically reflected in the article "Killing rats is killing birds", which had a substantial impact on public opinion (Lovett, 2012). However, almost ten years later, the threat continues, and the reported incidences in non-target species have barely diminished (Lohr and Davis, 2018;Lopez-Perea et al, 2015;Lopez-Perea et al, 2019;Nakayama et al, 2019;Seljetun et al, 2019). In 2014, our research group already presented results of a preliminary study in raptors of the Canary Islands (Ruiz-Suarez et al, 2014).…”

Asymptomatic Anticoagulant Rodenticide Exposure in Dogs and Cats—A French and Belgian Rural and Urban Areas Study

“…This prevalence may be underestimated due to the biological matrix used. Nevertheless, in Norway, 110 healthy dogs were tested for ARs and showed that only one sample contained difenacoum ( Seljetun et al, 2020a ), whereas the prevalence in non-target wildlife such as foxes was 50% ( Seljetun et al, 2019 ). Indeed, much higher levels of exposure have been reported in wild canids and felids, even when monitoring is performed on feces.…”