Pesticide Residues in Birds and Mammals - Pesticides: Evaluation of Environmental Pollution - page 443

species may be a result of direct ingestion of the poison baits or more habitually through
the consumption of contaminated invertebrates that ingest rodent baits, carcasses, feces,
or soil-bound residues (Spurr et al. 2005; Dowding et al. 2010). It has been shown that
snails or beetles can carry considerable amounts of AR residues (Eason and Spurr 1995;
Howald et al. 1999; Thorsen et al. 2000), and other insectivorous mammals such as shrews
( Sorex spp.) can also be in danger of exposition (Brakes and Smith 2005). The European
hedgehog has been investigated recently in the United Kingdom for the exposure to ARs,
showing that indirect contamination in carnivorous species, other than those who con-
sume directly poisoned rodents, is possible (Dowding et al. 2010). Results showed that
the prevalence of exposure was widespread, with 66.7% of 120 analyzed livers by HPLC/
MS from hedgehogs found dead positive for combined residues of FGARs (22.5%) and
SGARs (57.5%) (some animals presented more than one residue compound). However,
there was no clear pathological evidence found that this was a contributory factor to
lethal effects, as necropsy revealed no sign of hemorrhage. Samples were analyzed also
by HPLC with fluorescence detection (these are the results show in Table 14.6 ), and it was
found that the prevalence of exposition was clearly higher using HPLC/MS due to its
superior sensibility.
Red fox is a well-known carnivorous and the most widespread and abundant species
of fox. In France, a study of anticoagulant poisonings of wildlife carried out from 1991
to 1994 yielded 31 confirmed diagnoses for bromadiolone and chlorophacinone lethal
toxicoses, based on a liver threshold of 0.2 μg/g and/or lesions consistent with antico-
agulant poisoning (Berny et al. 1997). Recently, a noninvasive technique using feces
was developed to monitor both recent and previous exposure of foxes to bromadiolone,
useful to control baiting strategies and exposure to nontarget carnivores (Sage et al.
2010). The same study, in which animals were sacrificed at the end of the experimental
procedure and a complete necropsy was performed in the corpses, also revealed that
apparently red foxes were more susceptible to the effects of bromadiolone than dogs
(Sage et al. 2010).
Exposure of other predators such as mustelids, some representatives considered pests in
various countries, to ARs is well documented (see Table 14.6). A poisoning operation with
brodifacoum in New Zealand targeting rabbits also killed stoats and ferrets ( Mustela furo )
(Alterio 1996). Shore et al. (1996) analyzed the livers of 24 polecats in the United Kingdom
during 1992-1994, and SGAR residues were detected in 29% (7/24) of the animals, difena-
coum being the most prevalent one (6/7). During the period 1994-1997, the proportion was
similar (23%, 6/26), but bromadiolone was the residue most detected that time (Shore et al.
1999). In a subsequent study with newly added individuals, 35.1% (13/37) male and 38.5%
(5/13) female polecats were positive for difenacoum, bromadiolone, and, to a lesser extent,
brodifacoum (Shore et al. 2003). McDonald et al. (1998) showed that ARs were detected in
23% (9/40) of stoats and 30% (3/10) of weasels in England between 1996 and 1997, revealing
also that exposure was more prevalent in female stoats than in males. Analysis of polecat
feces confirmed rats as the principal prey items, although woodmice and voles were also
taken (Brakes and Smith 2005).
In France, Fournier-Chambrillon et al. (2004) estimated the exposure of 122 dead free-
ranging riparian mustelids of four species collected between 1990 and 2002 and found
residues of bromadiolone or chlorophacinone in 3% (1/31) of European minks ( Mustela
lutreola ), 15% (7/47) of American minks ( Mustela vison ), 15% (5/33) of polecats, and 27%
(3/11) of European otters of the collected carcasses. Another study with the latter spe-
cies detected 10% (2/20) individuals with bromadiolone residues (Lemarchand et al.
2010).