title: Polybrominated diphenyl ethers and multiple stressors influence the reproduction of free-ranging tree swallows (Tachycineta bicolor) nesting at wastewater treatment plants.
abstract: Reproductive success of birds is influenced by maternal factors, ambient temperatures, predation, food supply, and/or exposure to environmental contaminants e.g., flame retardants (FRs). Reproduction of tree swallows (Tachycineta bicolor) was compared among waste water treatment plants (WWTPs) and a reference reservoir in Ontario, Canada (2007-2010), to determine the importance of exposure to polybrominated diphenyl ether (PBDEs) FRs within a complex contaminant cocktail, relative to natural and biological factors known to influence avian reproduction. The birds primarily consumed insects emerging from the reference reservoir and WWTP outflows, where effluent mixed with receiving waters. FR egg concentrations were dominated by 5 PBDE congeners (∑5PBDEs): 2,2'.4,4',5-pentabromodiphenyl ether (BDE-99), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2'4,4',6-pentabromodiphenyl ether (BDE-100), 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153), and 2,2',4,4',5,6'-hexabromodiphenyl ether (BDE-154), with much lower concentrations of decabromodiphenylether (BDE-209), hexabromocyclododecane (HBCDD), and novel FRs. Although higher than ∑5PBDEs, polychlorinated biphenyls (PCBs) egg concentrations were unlikely to affect the swallows' reproduction. Clutch size and timing, fledging, breeding success, and predation, varied significantly among sites, generally being poorer at WWTP1 and better at WWTP2. The early reproductive stages were sensitive to some FRs at measured concentrations. The ∑5PBDEs, maternal age, and minimum ambient temperatures predicted onset of egg laying in the most parsimonious statistical model, and there were positive relationships between egg size and HBCDD or BDE-209 concentrations. However, there were no significant correlations with any reproductive measures, individual BDE congeners or low concentrations of novel FRs, in this first such report for novel FRs and wild birds. Tree swallows are passerines, and passerines may differ from birds of prey in their reproductive sensitivity to PBDE exposure: lay date, minimum temperatures, and predation, but not PBDE exposure, predicted reproductive productivity. Overall, there was some influence of the PBDEs available in these WWTP outflows on early reproductive parameters, but not reproductive output, of these passerines.
authors.affiliation: McGill University, Dept. Natural Resource Sciences, 21, 111 Lakeshore Road, Ste-Anne de Bellevue, Quebec H9X 3V9, Canada. Electronic address: tiffany.gilchrist@mail.mcgill.ca.
authors.forename: Tiffany T
authors.initials: TT
authors.lastname: Gilchrist
authors.affiliation: Ecotoxicology and Wildlife Health Division, Science & Technology Branch, Environment Canada, National Wildlife Research Centre, Ottawa, ON K1A 0H3, Canada. Electronic address: robert.letcher@ec.gc.ca.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Letcher
authors.affiliation: Ecotoxicology and Wildlife Health Division, Science & Technology Branch, Environment Canada, National Wildlife Research Centre, Ottawa, ON K1A 0H3, Canada. Electronic address: philippe.thomas@ec.gc.ca.
authors.forename: Philippe
authors.initials: P
authors.lastname: Thomas
authors.affiliation: McGill University, Dept. Natural Resource Sciences, 21, 111 Lakeshore Road, Ste-Anne de Bellevue, Quebec H9X 3V9, Canada; Ecotoxicology and Wildlife Health Division, Science & Technology Branch, Environment Canada, Canada Center for Inland Waters, 867 Lakeshore Road, Burlington, ON L7R 4A6, Canada. Electronic address: kim.fernie@ec.gc.ca.
authors.forename: Kim J
authors.initials: KJ
authors.lastname: Fernie
mesh_terms: D000818:Animals; D002170:Canada; D004784:Environmental Monitoring; D005260:Female; D005411:Flame Retardants / Q000032:analysis / Q000378:metabolism / Q000633:toxicity; D055768:Halogenated Diphenyl Ethers / Q000032:analysis / Q000378:metabolism* / Q000633:toxicity; D012098:Reproduction / Q000187:drug effects*; D046388:Swallows / Q000502:physiology*; D064091:Waste Disposal Facilities; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism* / Q000633:toxicity
chemical_list: D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Birds; Multiple stressors; PBDE; Reproduction; Tree swallows; Waste water treatment plant