LEIGHTON, F.A. 1993. The toxicity of petroleum oils to birds. Environ. Rev. 1: 92-103. Mortality of aquatic birds occurs regularly as a consequence of spills of petroleum oils. There are three different ways in which such oils can affect birds. (i) External contamination of feathers is the most common form of exposure, and the effect of oils on feathers is the single most devastating effect of oil on birds. Feathers absorb oil, become matted, and lose the critical properties of water repellency, insulation, and flight. Death results from combinations of hypothermia, starvation, and drowning. (ii) Avian embryos are highly sensitive to oil that contaminates the egg shell; amounts as little as 1-10 pL are lethal to embryos during the first half of incubation. (iii) Birds ingest oil when preening oiled plumage or ingesting oiled nutrients. At least three toxic effects of ingested oil are well documented: a nonspecific response as a stressor that is additive or synergistic with those of other stressors, impairments in reproduction ranging from lowered fertility to abandonment of reproductive effort, and severe oxidant damage to red blood cells. The effect of oil pollution on bird populations is very difficult to document and is likely to remain uncertain because of the many ecological factors that may occur in association with an oil-spill event.LEIGHTON, F.A. 1993. The toxicity of petroleum oils to birds. Environ. Rev. 1 : 92-103.Les deversements d'huiles de petrole entrainent frkquemment la mortalitk d'oiseaux aquatiques. Ces huiles agissent de trois faqons diffkrentes sur les oiseaux. (i) La forme d'action la plus frkquente et la plus dommageable pour les oiseaux consiste en une contamination exteme des plumes. Les plumes absorbent l'huile qui les enduit et celles-qi perdent leurs propriktks hydrophobes particuliitres, ainsi que celles d'isolation et d'aptitude au vol. La mort fait suite a l'hypothermie, a l'inanition et a la noyade. (ii) Les embryons d'oiseaux sont trits sensibles a l'huile qui contamine la coquille des oeufs; des quantitks aussi petites que 1-10 pL sont mortelles pour les embryons pendant la premikre partie de l'incubation. (iii) Les oiseaux ingkrent de l'huile en lissant leurs plumes couvertes d'huile ou en mangeant de la nourriture enduite d'huile. 11 existe au moins trois effets toxiques bien documentks de ]'ingestion d'huile : une rkaction non-specifique comme agent stressant qui s'ajoute de faqon synergique avec ceux d'autres agents stressants, une deterioration de la reproduction allant d'une baisse de fertilite jusqu'ri l'arrtt total de l'effort de reproduction et des dommages importants par oxydation aux globules rouges sanguins. 11 est trits difficile de reunir la documentation des effets de la pollution par l'huile sur les populations d'oiseaux et ceci risque de demeurer inchangk, compte-tenu des nombreux facteurs ecologiques qui peuvent ttre impliques en relation avec les kvknements de dkversement de pktrole.

Abstract-There is increasing concern that birds in terrestrial ecosystems may be exposed to spent lead shot. Evidence exists that upland birds, particularly mourning doves (Zenaida macroura), ingest spent lead shot and that raptors ingest lead shot by consuming wounded game. Mortality, neurological dysfunction, immune suppression, and reproductive impairment are documented effects of exposure to lead in birds. An ecological risk assessment on the impact of lead shot exposure in upland birds was conducted and is presented in the context of the new United States Environmental Protection Agency's Ecological Risk Assessment Paradigm. A considerable amount of spent lead shot is released into the environment each year from shooting and hunting. Doves collected from fields that are cultivated to attract mourning doves for hunting activities show evidence of ingestion of spent lead shot. Because lead can cause both acute and chronic toxicity if ingested by birds, and because there is evidence of widespread deposition of lead shot in terrestrial ecosystems, concern for impacts on upland game birds and raptors seems warranted. Although this ecological risk assessment does not clearly define a significant risk of lead shot exposure to upland game birds, this issue merits continued scrutiny to protect our upland game bird and raptor resources.

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Of 4,268 wild ducks sampled in Canada in 2005, real-time reverse transcriptase–PCR detected influenza A matrix protein (M1) gene sequence in 37% and H5 gene sequence in 5%. Mallards accounted for 61% of samples, 73% of M1-positive ducks, and 90% of H5-positive ducks. Ducks hatched in 2005 accounted for 80% of the sample.