The effects of grit supplementation and feed type on steel-shot ingestion in mallards

Lead poisoning by shot-pellet ingestion is an important cause of death in w aterfowl from wetlands that have high densities of lead-shot pellets and lo w availabilities of grit in their sediments. To evaluate grit supplementati on when mixed with baited grain as a method of reducing shot ingestion in w aterfowl, 24 mallards (Anas platyrhynchos) were kept in captivity to study the relationship between steel-shot, grit and grain ingestion in four exper iments. Steel-shot ingestion was more related to seeking grit than to feedi ng on grain, and it did not differ between two types of grain offered (rice or sorghum). Grit ingestion increased with grit supplementation and shot i ngestion was only slightly reduced. Calcareous grit used in the experiments had a shorter half-life (1.4 days) in the gizzard than values reported for siliceous grit (3.1 days). (C) 2000 Elsevier Science B.V. All rights reser ved.