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Wing bones of 4,190 ducks of seven species collected in 1972 and 1973 were analyzed for lead to provide a base line for lead burdens and to determine geographic patterns of lead exposure in these species. Lead residues ranged from trace amounts to 361 ppm and reflected the history of exposure to lead from ingested shotshell pellets and other sources. Wing bones of adults contained higher residues than did those of immatures. Levels were lower in birds from the Central Flyway than in those from other flyways.
Poisoning of North American waterfowl resulting from the ingestion of lead shot by ducks, geese, and swans causes an estimated annual mortality of 2% to 3% of the population. To alleviate this problem the search for a suitable substitute for lead has been underway since the early 1950's. Proposed substitutes for lead shot were evaluated in a series of acut toxicity tests with pen-reared mallards. Most candidate materials were as toxic to ducks as commercial lead shot. Coating or alloying lead with other materials only delayed mortality among dosed ducks.
Although the feeding ecology of raptors has attracted the attention of many scientists, aspects such as diet selection and foraging strategy are still poorly understood. This is particularly true for large species such as the white-tailed eagle. Representative assessments of the contribution of food sources containing toxins such as lead to raptor diets are scarce but are essential for optimising conservation efforts. This dissertation investigated the feeding ecology of white-tailed eagles to shed light on the interaction of such top predators with their environment and to improve the conservation management of this lead-exposed species. A use of complementary methods identified the most effective approach for dietary investigations on free-ranging raptors. The findings revealed that the foraging strategy of white-tailed eagles is influenced by both individual and environmental factors and corresponds to an efficient food intake in terms of optimal foraging theory. The main sources of lead fragments that induce fatal lead poisoning are shot mammalian carcasses which constitute important alternative diet components for white-tailed eagles during the hunting season. One approach to solve the lead poisoning problem can be the use of lead-free bullets by hunters that fragment into sufficiently large particles which would be avoided by scavenging eagles and birds with similar feeding behaviour.
Ecological Impacts of Toxic Chemicals presents a comprehensive, yet readable account of the known disturbances caused by all kinds of toxic chemicals on both aquatic and terrestrial ecosystems. Topics cover the sources of toxicants, their fate and distribution through the planet, their impacts on specific ecosystems, and their remediation by natural systems. Each chapter is written by well-known specialists in those areas, for the general public, students, and even scientists from outside this field. The book intends to raise awareness of the dangers of chemical pollution in a world dominated by industry and globalization of resources. Because the problems are widespread and far reaching, it is hoped that confronting the facts may prompt better management practices at industrial, agricultural and all levels of management, from local to governmental, so as to reduce the negative impacts of chemical contaminants on our planet.