A new technique to measure bird’s dietary exposure to pesticides Original Research Article

Current methods to analyse pesticide residues in wild animals are essentially forensic examination procedures. This paper describes a new approach to obtain samples from live birds for pesticide residue analysis without harm to the animal involved. The technique measures the dietary exposure and has been tested successfully in birds exposed to farm chemicals in Australia. Stomach flushing with warm water was used to obtain ‘flushing’ samples (stomach and droppings combined) from 11 species of birds at four locations near or away from cotton farms. Water samples from all sites were also taken. Immunoassays were used to analyse these samples for residues of DDE, DDT, diuron, endosulfan and parathion-methyl. ELISA is suited to environmental residue analysis because of its high sensitivity, small sample volume requirements, low cost and speed. Prior to the residue analysis, optimization of the assays and elimination of matrix effects are essential. Positive residues were found in 90% of the birds, their amounts varying up to four-orders of magnitude amongst individuals and species, with predators and insectivorous having higher levels than granivorous and nectivores. The technique can be applied to the same animal over a period of time, thus providing a useful tool for monitoring programs in environmental studies. Its application to ecological risk assessment and exposure are discussed.