Date of this Version
There is now an ongoing, unprecedented loss of species diversity throughout the world as well as a decline in the absolute numbers of organisms from the smallest microorganism to the largest mammal. The current loss of biota has several causes. One is the destruction, conversion, or degradation of entire ecosystems with the consequent loss of entire assemblages of species. Another is the accelerating loss of individual species within communities or ecosystems as a result of habitat disturbance, pollution, and exploitation. Third, and more subtle, is the loss of genetic variability. Selective pressures such as habitat alteration, the presence of chemical toxins, or regional climate changes may eliminate some genetically distinct parts of the population, yet not cause extinction of the entire species.
This is the first of several issues of Museum Notes that will discuss Nebraska's Endangered and Threatened species. Future issues will deal with fish, birds, amphibians, reptiles, mammals, and plants. As a prelude to this series of Museum Notes, we might ask "what does it mean to be Endangered or Threatened?" As defined by the Endangered Species Act of 1973, the term 'endangered species' means any species that is in danger of extinction throughout all or a significant portion of its range. Excluded from this definition would be any insect species determined to constitute a pest whose protection under the provisions of this Act would present an overwhelming and overriding risk to man. A 'threatened species' is any species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. Before a plant or animal species can receive protection under the Endangered Species Act, it must first be placed on the Federal list of endangered and threatened wildlife and plants. This listing program follows a strict legal process to determine whether to list a species depending on the degree of threat facing it.