Certain specific activities focus on protecting and managing endangered species as well as migratory bird populations. The first and most effective means of protection is through exclusion or prevention of intentional or unintentional entry of harmful invasive species. A second strategy uses tactics including detecting, eradicating, managing, or controlling specific pests that have become established. Third, certain endangered species need special protection against a host of attackers. Endangered species are rescued from illegal trade at ports of entry and protected within the United States.
Invasive species can be a threat to indigenous endangered species.
Finally, human populations need help in coping with the needs of certain organisms, such as migratory birds, so that human activity and wildlife can coexist. Organisms are intentionally brought in for biological control, including insects, fish, snails, plant pathogens, and nematodes. Entry may be authorized under certain conditions. Risk assessment uses scientific information to determine numbers and kinds of organisms that have the potential to become established and harmful. Sophisticated methodologies measure the level of risk.