Environmental contaminants in surrogate birds and insects inhabiting Southwestern Willow Flycatcher habitat in Arizona
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abstract
Several deformed Southwestern Willow Flycatchers (Empidonax traillii extimus) were reported in Arizona during the last few years. Environmental contaminants, particularly persistent bioaccumulative pollutants, have been associated with deformities in other birds from diverse areas of the United States. One objective of this study was to determine if environmental contaminants could be linked to deformities of the Southwestern Willow Flycatcher in Arizona. We measured levels of selected inorganic and organic contaminants in potential insect prey of the Willow Flycatcher and in avian surrogate species at selected sites within the San Pedro River and in Roosevelt Lake. DDE and PCBs were the only organochlorine compounds quantified above detection limits in all samples. None of the mean concentrations of DDE and PCBs in eggs, nestlings, or adult birds were near or above the threshold for potential detrimental effects on the birds themselves or on predators that may feed on them. Also, none of the concentrations of metals and metalloids in eggs, nestlings, and adults were at levels known to affect reproduction or that have been associated with deformities. Selenium was relatively elevated in bird samples (up to 5.8 g/g dry mass); however, these levels were still below those that have been associated with deformities in birds. We detected high concentrations of Sr (up to 450 g/g dry mass) in whole eggs of Yellow-breasted Chats (Icteria virens) that could affect eggshell strength, but more research is needed. Overall, the contaminants reported in this study are not likely to be implicated in the deformities observed in Southwestern Willow Flycatchers in the Lower San Pedro River and Roosevelt Lake.
