Indicator Species in Africa, and consistent with our earlier conclusions, there was little spatial congruence in the species richness of woody plants, large moths, butterflies, birds, and small mammals once differences in sampling effort were accounted for However, sets of forests selected using complementarity determined for single taxa were generally similar to those for all other taxa and hence served to capture well the species richness in all these other groups (Howard et al., 1998) If these results generalize to other parts of the world, they send an encouraging message to conservation managers struggling to identify the best areas to set aside as reserves and parks It says that a complementary and therefore efficiently selected chain of reserves based on a single indicator taxon (or perhaps two or three indicator taxa) may efficiently capture complementary sets of many other groups as well Unfortunately, the Ugandan results are not supported by similar studies in the Transvaal, elsewhere in Africa (van Jaarsveld et al., 1998) It may therefore be too soon to assume that we can find simple indicators for complementary reserve sets embracing many taxa as a means of conserving biodiversity Conclusions The term ‘‘indicator species’’ has three distinct meanings They are a species, or group of species, that reflect the biotic or abiotic state of an environment; reveal evidence for, or the impacts of, environmental change; or indicate the diversity of other species, taxa, or entire communities within an area The uses of indicator species in the first two senses of the word are very similar, differing largely in the fact that to indicate change, organisms need to be sampled more than once in the same place and in the same way Using organisms to indicate the state of, and changes in, the environment has numerous tried and tested applications, from detecting pollution to monitoring recovery of formerly degraded habitats, at many scales, from local to global The use of indicator species to predict the diversity of other, unstudied taxa for scientific or conservation reasons is much more contentious and may prove to be impossible with any degree of rigor See also: Birds, Biodiversity of Ecotoxicology Endemism Environmental Impact, Concept and Measurement of Greenhouse Effect Hotspots Keystone Species Paleoecology 263 References Bibby CJ, Collar NJ, Crosby MJ, et al (1992) Putting Biodiversity on the Map: Priority Areas for Global Conservation Cambridge: International Council for Bird Preservation Blaustein AR and Wake DB (1995) The puzzle of declining amphibian populations Sci Am 272: 56–61 Erisman JW and Draaijers GPJ (1995) Atmospheric Deposition in Relation to Acidification and Eutrophication Amsterdam: Elsevier Gaston KJ (1996a) BiodiversityFCongruence Prog Phys Geog 20: 105–112 Gaston KJ (1996b) Spatial covariance in the species richness of higher taxa In: Hochberg ME, Clobert J, and Barbault R (eds.) Aspects of the Genesis and Maintenance of Biological Diversity, pp 221–242 Oxford: Oxford University Press Gibbons DW, Reid JB, and Chapman RA (eds.) (1993) The New Atlas of Breeding Birds in Britain and Ireland: 1988–1991 London: Poyser Howard PC, Viskanic P, Davenport TRB, et al (1998) Complementarity and the use of indicator groups for reserve selection in Uganda Nature 394: 472–475 Huntley B and Birks HJB (1983) An Atlas of Past and Present Pollen Maps for Europe 0–13000 Years Ago Cambridge: Cambridge University Press van Jaarsveld AS, Fretag S, Chown SL, et al (1998) Biodiversity assessment and conservation strategies Science 279: 2106–2108 Lawton JH, Bignell DE, Bolton B, et al (1998) Biodiversity inventories, indicator taxa and the effects of habitat modification in tropical forest Nature 391: 72–76 McGeoch MA (1998) The selection, testing and application of terrestrial insects as bioindicators Biol Rev 73: 181–201 Oliver I and Beattie AJ (1996) Designing a cost-effective invertebrate survey: A test of methods for rapid assessment of biodiversity Ecol Appl 6: 594–607 Pimm SL and Lawton JH (1998) Planning for biodiversity Science 279: 2068–2069 Prendergast JR, Quinn RM, Lawton JH, Eversham BC, and Gibbons DW (1993) Rare species, the coincidence of diversity hotspots and conservation strategies Nature 365: 335–337 Pressey RL, Humphries CJ, Margules CR, Vane-Wright RI, and Williams PH (1993) Beyond opportunism: Key principles for systematic reserve selection TREE 8: 124–128 Ratcliffe DA (1980) The Peregrine Falcon Calton: Poyser Reid WV (1998) Biodiversity hotspots TREE 13: 275–280 Rosenberg DM and Resh VH (eds.) (1993) Freshwater Biomonitoring and Benthic Macroinvertebrates New York: Chapman & Hall Shaw IC and Chadwick J (1998) Principles of Environmental Toxicology London: Taylor & Francis Tucker GM and Heath MF (1994) Birds in Europe: Their Conservation Status Cambridge: Bird Life International