| The majority of avian pesticide field studies have focused on the ingestion of treated food items (oral exposure). Dermal exposure remains an important route of exposure, when birds come into contact with pesticides applied to foliage. The objectives of this thesis were to 1) develop, design and apply a chemical analysis methodology to detect selected organophosphate pesticides in samples of feet of migratory songbirds, and 2) to assess the potential dermal exposure of songbirds by looking at the frequency of exposure in a range of neotropical species. A total of 18 species of migratory songbirds were opportunistically sampled during the spring in 2007 and 2011 in downtown Toronto, Canada, during the migration to their breeding sites in Canada. Only the feet of dead birds colliding with lighted buildings were used for chemical analysis. The working hypothesis was that birds had been exposed via their feet to organophosphate pesticides while foraging on pesticide-treated crops in their wintering grounds. Among the four selected organophosphate pesticides in this study (i.e chlorpyrifos, fenthion, fenamiphos, and diazinon), only chlorpyrifos was detected in feet samples of six birds species, these being Black-throated blue warbler, Tennessee warbler, Northern parula, Northern waterthrush, Common yellowthroat and Blue-winged warbler. |
