Abstract
Considerable attention has been devoted to monitoring heavy metals in temperate zones of the world, largely due to the concentration of industries and populations in these regions. With increases in global transport of mercury, it has become important to examine the effects of mercury on components of tropical ecosystems, and to design biomonitoring schemes to assess environmental changes involving mercury. Tropical ecosystems differ from temperate ones in fundamental ways, including increased species diversity, and decreased niche width, spatial heterogeneity, food web lengths and complexity, productivity and soil laterization. Because of these differences, the fate and transport of mercury may differ in temperate and tropical systems, and it is suggested in this paper that bird feathers be used as a biomonitoring tool to assess broad-scale trends in mercury exposure, as well as being indicative of adverse effects on the birds themselves. In many ecosystems, some species of birds o ccupy top trophic levels. It is apparent that the mercury level in feathers of some tropical birds as high as those from temperature regions, exceeding levels associated with adverse effects in laboratory studies.