Pesticide Residues in Birds and Mammals - Pesticides: Evaluation of Environmental Pollution - page 442

Nevertheless, of 172 livers from tawny owls collected in two distant periods of years
examined in the United Kingdom for some SGARs, it was found that 33 (19.2%) of the
whole samples contained detectable concentrations of one or more of them, the individual
occurrence being 11.6%, 5.8%, 4.7%, and 0% for bromadiolone, difenacoum, brodifacoum,
and flocoumafen, respectively (Walker et al. 2008b). Although the SGARs have been
hypothesized as a potential cause for the decline of British owl populations, there was
found no clear variation or trend in exposure between individuals in the 1990-1993 and
2003-2005 examined periods in this work, and the authors concluded that there was no
clear evidence to implicate SGARs as a major factor affecting tawny owl numbers.
A recently published survey carried out in British Columbia and the Yukon region
of Western Canada between 1988 and 2003 (Albert et al. 2010), in which the livers of
78 barn owls, 61 great horned owls, and 25 barred owls ( Strix varia ) were examined,
70% had residues of at least one AR, and, of these, 41% had more than one detected.
Bromadiolone (52%) and brodifacoum (51%) were the most commonly detected ARs in
all three species, followed by difethialone (9%), diphacinone (5%), chlorophacinone (4%),
and warfarin (3%) residues. Only brodifacoum was found in barred owls to increase its
presence over time. Based on necropsy findings and residue levels, a final diagnosis of
SGAR poisoning was established for 6 animals (3 barred, 2 barn, and 1 great horned
owls), although other animals were considered suspected of AR poisoning based on the
liver residues.
The PBMS also carried out systematic AR residue analysis in European kestrels since
1997 (Walker et al. 2010). Using the same considerations for calculations explained above
for barn owls (LoQ of 0.01 μg/g WW), the adjusted percentage of birds with any detect-
able SGAR liver residue was 50%-70% (mainly due to bromadiolone and difenacoum),
with no apparent temporal trend. However, individually it was found that brodifacoum
progressively increased from about 5% during the period 1997-2000 to a 17% in the period
2005-2006 (Walker et al. 2010).
Another diurnal raptor monitored by the PBMS is the red kite (Walker et al. 2010). Livers
of 23 red kites found dead in Great Britain between 1994 and 2005 were analyzed, and
73.9% of them showed one or more residues of SGARs (Walker et al. 2008a). In France,
Berny and Gaillet (2008) found that over the period 1992-2002, 27 out of 62 red kites sub-
mitted to the Toxicology Laboratory of the College of Veterinary Medicine in Lyon were
diagnosed of AR poisoning, with 24 cases due to bromadiolone and 3 due to chlorophaci-
none ( Table 14.5 ).
14.6.2.2 Mammals
ARs continue to be a major cause for morbidity and mortality for pets such as dogs and
cats and can even affect production animals (Robben et al. 1998; Kohn et al. 2003; Berny
et al. 2005, 2010; Del Piero and Poppenga 2006). Carnivorous mammals are commonly
exposed to ARs usually when they feed on dead and dying poisoned rats and mice (or
other rodent species), although a few cases of suspected or confirmed primary poison-
ing have been described in the literature in herbivorous or omnivorous species such as
gray squirrels ( Sciurus carolinensis ), common hares ( Lepus capensis ), Iberian hares ( Lepus
granatensis ), European rabbits, raccoons ( Procyon lotor ), wild boars, sheep ( Ovis aries ), white-
tailed deers, red deers ( Cervus elaphus ), and roe deers ( Capreolus capreolus ) (Berny et al. 1997,
2005; Stone et al. 1999; Eason et al. 2002; Del Piero and Poppenga 2006; Olea et al. 2009).
The European hedgehog ( Erinaceus europaeus ) is an omnivorous mammal that feeds
mainly on a wide range of invertebrates, but preferring insects. Exposure to ARs in this