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WHAT IS ENDANGERED?
By Sean Henahan, Access Excellence
ATHENS, Ga. (2/6/97) As intensive urbanization and agriculture
put more species in line for the endangered list, better science is needed
to determine which plants and animals are at greatest risk, according to
a new study authored by U.S. Secretary of the Interior Bruce Babbitt and
Dr. Ron Pulliam, director of the National Biological Service.
The primary conlusion reached by Babbitt and Pulliam is that managing for a single endangered species may put other species at risk and is no longer a reasonable policy option. Rather, it is essential to know which species are most vulnerable and which human activities threaten them, they report. "The idea is to protect species that are already endangered, but to take steps to help prevent future endangerment and therefore allow more local control over conservation issues," said Pulliam, who is on leave from his post as professor of ecology at the University of Georgia. Pulliam said that a crucial element in preventing further species endangerment is to have a good idea of which species are currently neither endangered nor threatened but may be in the future. That has been one of the goals of the National Biological Service under Pulliam, who served as its first director. Until recently there has been no systematic study of such cases, and much evidence has been anecdotal rather than based on solid science, Pulliam said. Still, a considerable amount of evidence has been uncovered in the past few years in identifying species that could be threatened. He said one federal program has been using data gathered by the U.S. Fish and Wildlife Service to determine candidates for the list of endangered species. "We really must learn about these species early enough so that we can develop conservation plans for them," said Pulliam. In a companion artcile, Dr. Andy Dobson and colleagues from Princeton University note that "hot spots" for endangered species tend to occur where the ranges of many endemic species overlap with intensive urbanization and agriculture. Pulliam and Babbitt note that endemic species, by definition, have a restricted geographic distribution. Dobson and his colleagues say that endemic species are prone to extinction, and especially, say Pulliam and Babbitt, "in the face of rapid habitat loss or degradation." The researchers highlight Hawaii, Florida and California as having both the most endemic species and the most endangered species. The high number of Hawaiian endemics is a result of the small size of the islands and their extreme isolation.Moreover, because coastal Florida was under water much of the past 10 million years, higher ridges of land were isolated and excellent for the development of species. For its part, California has unusual habitat features and a Mediterranean climate that has led to a development of high numbers of endemic species. Pulliam and Babbitt note that the introduction of exotic species has led to species declines, particularly in Hawaii. The problem is serious in the continental U.S. as well. Problems have been caused by such exotic species as the sea lamprey, grass carp, Asian clam and zebra mussel. These, along with river dredging, impoundments and other river developments may be responsible for the endangerment of hundreds of fish, mollusks and other aquatic species. There are some bits of good news amid the doomsaying. Some species have recovered and others are doing so. The bald eagle, for instance, has recently been downgraded in status from endangered to threatened. The report appeared in the Jan. 23, 1997 issue of Science
Related information on the Internet AE Activity: Create a Field Guide of Local Plants AE Activity: Endangered Species Act Project
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