Assessment of anticoagulant rodenticide exposure in six raptor species from the Canary Islands (Spain)

Abstract

Anticoagulant rodenticides are highly toxic compounds that are widely used for pest control of rodents, but that also may threaten the wildlife's health. This work aimed to assess the exposure to first- and second-generation anticoagulant rodenticides (ARs) in six birds of prey species from the Canary Islands (Spain). The concentrations of seven widely used ARs were determined by LC-MS/MS in 104 liver samples of six species of birds of prey (Buteo buteo, Accipiter nisus, Falco pelegrinoides, Falco tinnunculus, Asio otus, and Tyto alba). We determined that 61% of the livers had detectable residues of at least one AR. The most frequently detected AR was bromadiolone, which was detected in 60.3% of the positive cases. The detection frequencies of these compounds varied widely, depending on the species. More than 75% of the A. nisus, T. alba, and A. otus individuals had detectable rodenticide residues in the liver. However, F. tinnunculus exhibited the highest concentrations of AR, with median values above 100 ng/g w.w. We did not detect first-generation ARs in any of the samples. When grouped, nocturnal species exhibited higher AR concentrations than diurnal species (P<0.001). The residue levels were higher among small mammal-eaters than bird-eaters (P<0.01). While most animals exhibited no macroscopic signs of coagulation disorders, approximately 35% exceeded the threshold levels of toxicity, which suggests that these compounds could weaken these animals in their natural environment. In conclusion, the control of rodent populations by ARs suggests that these compounds will enter the food chain and thus threaten the vulnerable populations of raptors on the Canary Islands. Our findings require authorities to ban or strictly control the use of these rodenticides in the natural environment for the conservation of raptors and other predatory species.

A review: poisoning by anticoagulant rodenticides in non-target animals globally

“…Of these, 19 papers report poisoning of raptors. There are six publications from the U.S.A. [9, 42, 45, 48,49,50], three from Canada [1, 18, 55], nine from the U.K. [7, 19, 31, 46, 47, 58,59,60,61], two from France [13, 25], three from Spain [28, 43, 44], two from Denmark [5, 11], one from Norway [26], and four from New Zealand (NZ) [6, 8, 14, 35]. These reports and the proposed exposure pathways are summarized below.…”

“…Altogether, there were 2,694 out of 4,891 individuals (55%) of non-target animals have been reported to have AR residues in their livers between 1981 and 2013 [1, 5,6,7,8,9, 11, 13, 14, 18, 19, 25, 26, 28, 31, 35, 42,43,44,45,46,47,48,49,50, 55, 58,59,60,61](A)FGARsSGARsWarfarinCouma-tetralylDipha-cinoneChloro-phacinoneBrodi-facoumBroma-dioloneDifen-acoumDifeti-aloneFlocou-mafenDetection rate (%)1.04.55.05.631.030.026.05.05.7The number of detection27108991131,4651,3461,048101175The number of analysis2,6392,3911,972…”

Poisoning by Anticoagulant Rodenticides in Humans and Animals: Causes and Consequences

“…Wildlife expositions or intoxications to ARs have been reported around the world for many mammals such as minks [70], bobcats [71], stoats and weasels [72], foxes [73,74] and boars [67] and as well for many birds [75][76][77]. Exposition of ish was reported near an island where an eradication of rodent with brodifacoum was performed and the risk for human through the consumption appeared very low [78].…”

“…macroscopic haemorrhages with no trauma) have been statistically characterised as representative of a high-risk toxic threshold [84]. According to these criteria, hepatic concentrations above 0.2 mg/kg have been associated with mortalities in raptors and small mustelids from Denmark [85], in raptors and hedgehogs from Mediterranean region of Spain [86], in six raptor species from Canary Islands, Spain [77].…”

Quantification of potential exposure of gray partridge (Perdix perdix) to pesticide active substances in farmlands

“…However, little is known in agricultural landscapes. Exposure of birds of preythat benefit from dedicated surveys such as the Predatory Bird Monitoring Scheme in U.K. -to rodenticides is one exception (Christensen et al, 2012;Hughes et al, 2013;Ruiz-Suarez et al, 2014;Walker et al, 2008). As far as eggs are concerned, studies reporting an exposure to contaminants mainly deal with marine and fresh water birds, and birds of prey.…”