Anticoagulant Rodenticide Exposure in an Urban Population of the San Joaquin Kit Fox (original) (raw)
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Anticoagulant Rodenticide Exposure in an Urban Population of the can Joaquin Kit Fox
Concerned that San Joaquin kit foxes from urban areas may be exposed to commensal anticoagulants, the California Department of Fish and Game, Pesticide Investigations Unit, in conjunction with the Endangered Species Recovery Program's Urban Kit Fox Project, began monitoring San Joaquin kit foxes from the Bakersfield, CA population. Necropsies were performed and liver tissue samples collected from kit fox carcasses. Livers from archived kit foxes dating back to 1977 were also analyzed. A non-urban population of San Joaquin kit foxes from Lokern was used as a control. Other predators in the area, including coyotes and red foxes, were also analyzed for comparison. Between 1999 and 2007, tissue samples from 45 animals have been analyzed for residues of anticoagulant rodenticides. Anticoagulant compounds identified included brodifacoum, bromadiolone, pival, and chlorophacinone. Twenty-six of the 30 San Joaquin kit foxes from Bakersfield contained at least one anticoagulant, and the m...
Journal of wildlife diseases, 2015
Anticoagulant rodenticides are widely used in urban areas to control rodent pests and are responsible for secondary poisoning in many nontarget wildlife species. We tested the livers of five coyotes (Canis latrans) in the Denver Metropolitan Area, Colorado, US, for anticoagulant rodenticides. All five livers were positive for brodifacoum, with values ranging from 95 ppb to 320 ppb, and one liver was positive for bromadiolone, with a value of 885 ppb. Both of these rodenticides are second-generation anticoagulants, which are more potent and more likely to cause secondary poisoning than first-generation anticoagulants due to their accumulation and persistence in the liver. We concluded that exposure to these rodenticides may have caused the death of at least two of the five coyotes, and urban coyotes in our study area are commonly exposed to rodenticides.
Journal of Veterinary Diagnostic Investigation
Exposure of wildlife and domestic animals to anticoagulant rodenticides (ARs) is a worldwide concern, but few methods exist to determine residue levels in live animals. Traditional liver detection methods preclude determining exposure in live wildlife. To determine the value of assessing AR exposure by fecal analysis, we compared fecal and liver residues of ARs in the same animals. We collected liver and fecal samples from 40 apparently healthy red foxes ( Vulpes vulpes) potentially exposed to ARs, and quantified brodifacoum, bromadiolone, coumatetralyl, difenacoum, difethialone, and flocoumafen residues by liquid chromatography–tandem mass spectrometry. Residues of ARs were detected in 53% of the fecal samples and 83% of the liver samples. We found good concordance between AR residues in feces and liver for coumatetralyl, difenacoum, and difethialone. Bromadiolone occurred in significantly greater frequency in livers compared to feces, but no significant difference in concentration...
Prevalence of Anticoagulant Rodenticides in Feces of Wild Red Foxes (Vulpes Vulpes) in Norway
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.
Rodenticide Exposure Among Endangered Kit Foxes Relative to Habitat Use in an Urban Landscape
2014
Endangered San Joaquin kit foxes (Vulpes macrotis mutica) inhabiting Bakersfield, California exhibit a high incidence of exposure to anticoagulant rodenticides (ARs). We examined kit fox habitat use in an effort to determine potential sources of AR exposure. Kit fox capture, den, night, and mortality locations were assigned to one of 10 habitat categories. Using all available locations, foxes that tested positive for second generation anticoagulant rodenticides (SGARs) were located more frequently on golf courses while those testing negative were located more frequently in commercial areas. Foxes that tested positive for first generation anticoagulant rodenticides (FGARs) were located more frequently in industrial areas while those testing negative were located more frequently on golf courses. Based on night locations (when foxes are foraging), foxes that tested positive for SGARs were found more frequently in undeveloped and golf course habitats. Foxes that tested positive for FGARs were found more frequently in undeveloped, campus, and industrial habitats. Although available data were not sufficient to identify specific point-sources of AR exposure for foxes, golf courses appeared to be used more frequently by foxes exposed to SGARs. However, sources of exposure likely are abundant and widespread in the urban environment. Based on the results of this study, we recommend (1) investigating patterns of AR use in Bakersfield, (2) conducting an outreach program to emphasize the risk from ARs to kit foxes and other wildlife, and (3) continuing to monitor the incidence and patterns of AR exposure among kit foxes in Bakersfield.
Exposure of non-target wildlife to anticoagulant rodenticides in California
Proceedings of the Vertebrate Pest Conference, 2000
The California Department of Fish and Game collected and analyzed tissue samples from non-target birds and marrunals for anticoagulant rodenticides from 1994 through 1999. Many of these animals were collected in recently urbanized areas adjacent to wildlands where they were either found dead or trapped and euthanized as vertebrate pests. The results of the analyses indicate a high frequency of exposure to the anticoagulant rodenticide brodifacoum. Fiftyeight percent of the animals examined had been exposed to brodifacoum, 19% to bromadiolone, 9% to diphacinone and 8 % to chlorophacinone. All of the identified anticoagulants are registered for use to control commensal rodents found in and around structures and are available for sale "over-the-counter" for homeowner use. Brodifacoum and bromadiolone are registered exclusively for commensal rodent control. This paper assesses the frequency of anticoagulant rodenticide residues in tissues of non-target mammalian and avian wildlife and the possible impacts.
Proceedings of the Vertebrate Pest Conference, 2012
A 15-year study of carnivores in an urban landscape in southern California has revealed a high incidence of exposure of non-target wildlife to anticoagulant rodenticides (ARs). All carnivore species studied, including mountain lions, coyotes, bobcats, and gray foxes, have tested positive for exposure to the toxicants. Anticoagulant residues have been detected in post-mortem liver samples at a rate of 83-93% of individuals tested, for coyotes, bobcats, and mountain lions, the 3 species for which we have extensive sampling. We have also documented mortalities caused directly by exposure to ARs in all 4 species, particularly in the canids. In both felid species, we found a positive correlation between AR exposure and mange disease, specifically notoedric mange. The incidence of fatal mange infection in bobcats has been at epizootic levels since 2002 in our study area, and more recently outbreaks of the disease have been documented in several other populations in California, all apparently (where testing has been done) in association with exposure to ARs. There are no previously reported instances of epizootics of notoedric mange in any wild felid population. Carnivore exposure to these toxicants appears to be largely secondary (or tertiary, as may be the case in mountain lions) through consumption of their natural prey. In our most recent work, we have evaluated AR exposure of carnivore prey species, including rodents and lagomorphs. We have documented exposure in ground squirrels and woodrats, both of which are regularly consumed by gray foxes, coyotes, and bobcats. Overall, we have found widespread exposure of non-target wildlife to these toxicants, with potentially significant consequences for some species.
Chemosphere, 1997
This paper presents the result of a 4 year survey in France (1991-1994) based on the activity of a wildlife disease surveillance network (SAGIR). The purpose of this study was to evaluate the detrimental effects of anticoagulant (Ac) rodenticides in non-target wild animals. Ac poisoning accounted for a very limited number of the identified causes of death (1-3%) in most species. Predators (mainly foxes and buzzards) were potentially exposed to anticoagulant compounds (especially bromadiolone) via contaminated prey in some instances. The liver concentrations of bromadiolone residues were elevated and species-specific diagnostic values were determined. These values were quite similar to those reported in the litterature when secondary anticoagulant poisoning was experimentally assessed.
Environmental Chemistry and Ecotoxicology, 2020
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Environmental Science and Pollution Research, 2019
The extensive use of anticoagulant rodenticides (ARs) results in widespread unintentional exposure of non-target rodents and secondary poisoning of predators despite regulatory measures to manage and reduce exposure risk. To elucidate on the potential vectoring of ARs into surrounding habitats by non-target small mammals, we determined bromadiolone prevalence and concentrations in rodents and shrews near bait boxes during an experimental application of the poison for 2 weeks. Overall, bromadiolone was detected in 12.6% of all small rodents and insectivores. Less than 20 m from bait boxes, 48.6% of small mammals had detectable levels of bromadiolone. The prevalence of poisoned small mammals decreased with distance to bait boxes, but bromadiolone concentration in the rodenticide positive individuals did not. Poisoned small mammals were trapped up to 89 m from bait boxes. Bromadiolone concentrations in yellow-necked mice (Apodemus flavicollis) were higher than concentrations in bank vole (Myodes glareolus), field vole (Microtus agrestis), harvest mouse (Micromys minutus), and common shrew (Sorex araneus). Our field trials documents that chemical rodent control results in widespread exposure of non-target small mammals and that AR poisoned small mammals disperse away from bating sites to become available to predators and scavengers in large areas of the landscape. The results suggest that the unintentional secondary exposure of predators and scavengers is an unavoidable consequence of chemical rodent control outside buildings and infrastructures.