In 1967, the U.S. Fish and Wildlife Service began participating in a multi-agency monitoring program called the National Contaminant Biomonitoring Program. Monitoring studies search for the presence of contaminants (such as lead or polychlorinated biphenyls) in the tissues of animals. Constant monitoring allows biologists to recognize problems and trends over time. Tissue samples from wing bees and starlings collected from sites throughout the United States were analyzed for organochlorine compounds and some heavy metals. This monitoring program continued through 1992 and provided good documentation of the gradual decrease of organochlorine residues nationwide, particularly DDT. In 1991, the Service initiated development of a new monitoring program called Biomonitoring of Environmental Status and Trends. The program initially consisted of monitoring lands and habitat used by protected species. In addition to cleanup projects, the Service issues consumption advisories in order to protect people from eating fish or waterfowl that may have high levels of chemicals dangerous to human health. For example people have been advised not to eat certain species of sport fish and waterfowl near the San Francisco Bay National Wildlife Refuge in California because high mercury levels have been documented in fish and ducks there. Monitoring service lands has resulted in development of the Environmental Conservation Online System at http://ecos.fws.gov/ecos, which provides access to the Contaminant Information Management System and a manual, which is designed to provide a logical stepwise process for identifying contaminants, their sources, and exposure pathways.