title: Increased rodenticide exposure rate and risk of toxicosis in barn owls (Tyto alba) from southwestern Canada and linkage with demographic but not genetic factors.
abstract: Among many anthropogenic drivers of population decline, continual rapid urbanization and industrialization pose major challenges for the survival of wildlife species. Barn owls (Tyto alba) in southwestern British Columbia (BC) face a multitude of threats ranging from habitat fragmentation to vehicle strikes. They are also at risk from secondary poisoning of second-generation anticoagulant rodenticides (SGARs), a suite of toxic compounds which at high doses results in a depletion of blood clotting factors leading to internal bleeding and death. Here, using long-term data (N = 119) for the hepatic residue levels of SGAR, we assessed the risk of toxicosis from SGAR for the BC barn owl population over the past two decades. We also investigated whether sensitivity to SGAR is associated with genetic factors, namely Single Nucleotide Polymorphisms (SNPs) found in the CYP2C45 gene of barn owls. We found that residue concentration for total SGAR was significantly higher in 2006-2013 (141 ng/g) relative to 1992-2003 (57 ng/g). The proportion of owls exposed to multiple SGAR types was also significantly higher in 2006-2013. Those measures accordingly translate directly into an increase in toxicosis risk level. We also detected demographic differences, where adult females showed on average lower concentration of total SGAR (64 ng/g) when compared to adult males (106 ng/g). Juveniles were overall more likely to show signs of toxicosis than adults (33.3 and 6.9 %, respectively), and those symptoms were positively predicted by SGAR concentrations. We found no evidence that SNPs in the CYP2C45 gene of barn owls were associated with intraspecific variation in SGAR sensitivity. We recommend several preventative measures be taken to minimize wildlife exposure to SGAR.
authors.affiliation: Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada. andrewhuang220@gmail.com.|Environment and Climate Change Canada (Science and Technology Branch), 5421 Robertson Rd, Delta, BC, V4K 3N2, Canada. andrewhuang220@gmail.com.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Huang
authors.affiliation: Environment and Climate Change Canada (Science and Technology Branch), 5421 Robertson Rd, Delta, BC, V4K 3N2, Canada.|Avian Research Centre, Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: John E
authors.initials: JE
authors.lastname: Elliott
authors.affiliation: Environment and Climate Change Canada (Science and Technology Branch), 5421 Robertson Rd, Delta, BC, V4K 3N2, Canada.
authors.forename: Sofi
authors.initials: S
authors.lastname: Hindmarch
authors.affiliation: Environment and Climate Change Canada (Science and Technology Branch), 5421 Robertson Rd, Delta, BC, V4K 3N2, Canada.
authors.forename: Sandi L
authors.initials: SL
authors.lastname: Lee
authors.affiliation: Environment Canada (Science and Technology Branch), National Wildlife Research Centre, Carleton University, Ottawa, ON, K1A 0H3, Canada.
authors.forename: France
authors.initials: F
authors.lastname: Maisonneuve
authors.affiliation: Animal Health Centre, British Columbia Ministry of Agriculture, 1767 Angus Campbell Rd, Abbotsford, BC, V3G 2M3, Canada.
authors.forename: Victoria
authors.initials: V
authors.lastname: Bowes
authors.affiliation: Avian Research Centre, Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Cheng
authors.affiliation: Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada.|Environment and Climate Change Canada (Science and Technology Branch), 5421 Robertson Rd, Delta, BC, V4K 3N2, Canada.
authors.forename: Kathy
authors.initials: K
authors.lastname: Martin
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000633:toxicity*; D001955:British Columbia; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000633:toxicity; D012306:Risk; D012378:Rodenticides / Q000633:toxicity*; D020305:Strigiformes / Q000502:physiology*
chemical_list: D000925:Anticoagulants; D004785:Environmental Pollutants; D012378:Rodenticides
keywords: Barn owl; British Columbia; Cytochrome P450 gene; Demographic differences; Second-generation anticoagulant rodenticide (SGAR); Temporal differences