Granular insecticides and birds: Factors to be considered in understanding exposure and reducing risk

Abstract

AbstractGranular insecticides are used extensively, and many are highly toxic to birds. Here we discuss potential routes of avian exposure to granular insecticides and factors influencing those routes, suggest possible corrective measures for reducing exposure, and identify areas of needed research. Potential routes of exposure include inhalation or dermal absorption, inadvertent ingestion of granules, ingestion of prey or plant material containing pesticide residues, mistaking granules for food, and consuming granules as a source of grit. Bird consumption of granules for grit depends on factors affecting availability, bird behavior, grit/granule characteristics preferred by birds, and grit/granule retention in the gizzard. Avian exposure to granular insecticides may be reduced by taking into account factors such as application rate/incorporation of granules, habitat‐use patterns of birds, granule integrity in the field, rate of release of insecticide from the granules, and consumption of granules as a source of grit or food. Altering certain physical characteristics of insecticide granules may reduce avian exposure; these include granule size, shape and surface texture, composition, color, and insecticide load. Research needs include evaluations of the U.S. Environmental Protection Agency's current granular risk index, the relative importance of the various potential routes of exposure, grit‐use patterns of birds, and bird habitat use and behavior in treated fields.