The toxicity of petroleum oils to birds

摘要: 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 μL 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.Key words: oil, petroleum, pollution, bird, toxicity, poison.