Mammals at risk

Although the least speciose of tetrapod classes, mammals are also of particular interest to many people. Even if we leave our own species aside, mammals dominate many terrestrial ecosystems as well as some aquatic habitats. Mammals include the largest animal the world has ever known, blue whales (Bal-aenoptera musculus). Mammals reside atop many food chains, comprise vital links in most terrestrial-vertebrate food webs, and consume primary or secondary production everywhere they occur. Furthermore, perhaps more than any other class of organisms, mammals are threatened by changes occurring at the hand of Wise or Knowing Man. World Conservation

Red wolves (Canis rufus) have been reintroduced into the wild by the Nature Conservancy in North Carolina, USA. (Photo by Stephen J. Krasemann/ Photo Researchers, Inc. Reproduced by permission.)

Union (IUCN) data from 2002 suggest that almost one in four mammalian species may be in danger of extinction within the foreseeable future.

When considering threats to biodiversity, we should remember that different species face different threats, and many, if not most species, are menaced by multiple factors. For example, Miss Waldron's red colobus (Procolobus badius wal-droni), an African monkey declared extinct in September 2000, suffered intensely from both deforestation and hunting for the bushmeat trade. The black-footed ferret (Mustela nigripes) approached extinction because of habitat conversion, destruction of its prey, and infectious diseases contracted from domestic animals. Sea otters (Enhydra lutris) were exploited for the fur trade and killed by fisherman who considered them competitors for shellfish. And presently, their recovery has been slowed by depredations by killer whales (Orcinus orca). Despite the admitted complexity of extinction processes, we review four principle threats to mammalian species: habitat destruction, direct exploitation, introduction of exotics, and infectious disease.

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