Blue Lists of Threatened Species with Stabilized or Increasing Abundance: a New Instrument for Conservation

To counter the often depressing information contained in Red Lists and similar lists of threatened species, we propose the use of Blue Lists that enumerate those red list species experiencing lasting overall stabilization or an increase in abundance in the region considered. Blue lists are (mostly) a subset of the Red Lists. We defined three main categories for blue-listed species: (1) those whose increases merit delisting from the Red List; (2) those increasing in abundance, but not enough to warrant delisting; and (3) those whose abundance is stable. Remaining categories outside the Blue List include (1) decrease; (2) (local) extinction; and (3) change in abundance unknown. For practical use, information on conservation or recovery techniques necessary for maintaining or promoting the species could be added to the lists. In a test region of 3431 km2in northern Switzerland, representative of hilly and densely populated areas in central Europe, we enumerated Blue Lists for 122 species of all the vertebrate classes and 722 vascular plant species, all of which are on the regional Red Lists. Large differences exist between these systematic groups in the proportions of species in the different categories. Overall, Blue Lists comprise approximately one-third of the red-listed species considered. For a further 50%, nature conservation techniques for maintenance or promotion are known but have not yet been applied effectively. If all known techniques were applied to a greater extent, the persistent decline of most of the species in the region could be stopped or reversed. We discuss the scientific and psychological weaknesses and strengths of the Blue Lists. They can strengthen public motivation for conservation and advance self-confidence among conservationists by quantifying and stressing successes in species conservation, by giving this positive information an identity, by showing promising possibilities for action, and by providing a useful public relations tool. The Blue List concept can also be applied to species covered by the U.S. Endangered Species Act and by The Nature Conservancy's ranking system on the global, national, or regional scale.