Director, New York Zoological Society, Bronx, New York
In the preservation of biological diversity, the use of technology is a last resort. When the preservation of ecosystems falters, their fragments may have to be cared for piece by piece.
A species of limited distribution faces at least four obstacles. First, there may not be sufficient habitat and the possibility of obtaining numerous large new nature preserves is remote. Even protecting some areas already designated as preserves is not proving possible, and no land whatsoever will be set aside for large numbers of species. Second, many of the preserved habitats will be in pieces too small and too subject to change to sustain unmanaged, genetically and demographically viable populations of the animals and plants they seek to protect (Soulé and Wilcox, 1980). Third, although the majority of wild species must persist outside of wildlife preserves, large land vertebrates and great aggregations that conflict with humans will be mostly confined to refuges and those outside will require continual monitoring, protection, and help. Finally, human populations will continue to grow for some time, inexorably reducing resources available to other species, while human land-use patterns, cultural attitudes, and economic practices will continue to shift and change (Myers, 1979).
Despite the factors mentioned above, the loss of a wild population is not always the result of irreversible habitat change. It can come about for transient economic