Endangered Species Handbook

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Vanishing Species

Threatened Species of the World

     The 2000 IUCN Red List found 3,507 vertebrates and 1,928 invertebrates in high degrees of threat worldwide (Hilton-Taylor 2000). Plants classified as Critical, Endangered or Vulnerable totaled 5,611 species.  These are minimum figures because only birds and mammals have been thoroughly examined for status.  When assessments are carried out on the remaining species, the list will doubtless grow far longer.
     Many of the most magnificent, graceful, beautiful and zoologically curious animals on Earth are threatened with extinction.  A growing number of these, such as sea turtles, sharks and crocodiles, have survived virtually unchanged for hundreds of millions of years, and if not for the human activities that are pushing them toward extinction, they would likely survive millions more.
     Almost all the graceful cranes, on Earth since the Miocene Epoch, are endangered from loss of habitat and hunting.  The entire family of prehistoric-looking rhinoceros is teetering on the brink of extinction.  New Zealand's extraordinary and primitive kiwis and ancient tuatara lizards, which have survived since the dinosaur epochs, may be lost in the next few decades.  Eleven of the 16 species of penguins are now threatened, nine in higher categories (BI 2000).  Seabirds of many types, including the majority of albatross, are now listed. 
     The most surprising finding was the high number of mammals listed:  2,046 species, of which 1,130 species were in higher categories of threat (Critical, Endangered and Vulnerable).  Thus, of the approximately 4,000 species of mammals, 28 percent are highly threatened, and more than half are in some degree of threat.  They are the most imperiled class of animals.  Twelve percent of birds, or one in eight species, are listed in higher categories of threat (1,186 species), and an additional 809 species are in lesser categories (Near-Threatened, Conservation Dependent, or Data Deficient), totaling 1,995 species or about 18 percent of the world's birds (BI 2000).  Reptiles are a group less well assessed, but 750 species are at risk in all categories, according to the 2000 IUCN Red List.  Amphibians, which number about 4,550 species worldwide, have a minimum of 226 threatened species, and a large additional number that have not been thoroughly assessed.  Likewise, very few marine fish are listed by the IUCN because so little is known of their status.  Some progress is being made in assessing marine fish, especially coral reef fish and sharks and rays.  By 2003, a complete assessment of the shark family is planned by IUCN (Hilton-Taylor 2000).  Approximately 1,183 fish are listed in the most recent IUCN Red List in various categories of threat.  The majority of these are freshwater species, which represent 6 percent of all known fish. 
     The rate at which animals and plants are declining has reached such proportions that even familiar species considered common with stable populations only a decade ago are now threatened.  The African Lion (Panthera leo) and many African antelope, Giraffes and wildebeests are in serious decline, or exist only in parks and reserves, categorized as Conservation Dependent.
      Animals listed as Near-Threatened or Data Deficient totaled 3,324 species, of which 2,364 species are vertebrates in the 2000 IUCN Red List.  The grand total of 8,759 vertebrates in all categories comprises 20 percent of all mammals, birds, reptiles, amphibians and fish on Earth.  In the early 1980s, only 1,000 vertebrates were listed by the IUCN.  This means that in just 20 years, this total has risen by almost 900 percent.
     Plants have been assessed in several reports.  The 1997 IUCN Red List of Threatened Plants (Walter and Gillett 1998) was supplemented--and many species reassessed--by the 2000 IUCN Red List (Hilton-Taylor 2000).  Plants from Cameroon, the Galapagos, Mauritius and South Africa were added to the 2000 list.  A total of 6,932 plants were listed in all categories, 5,611 in higher categories of threat.  In spite of these major undertakings, only conifers were thoroughly assessed.  The 1997 study, using one type of definition based on status alone, found 30 percent of all conifers to be either Endangered or Vulnerable; the 2000 reappraisal, using new criteria, determined that 16 percent were threatened (Hilton-Taylor 2000).  When far more species of plants are assessed, The Nature Conservancy study of US plants (Stein et al. 2000), which found one-third of plants to be threatened, may be indicative of a great decline in the world's plants. 
     As in the case of animals, many of the Earth's oldest species of plants are at high risk of extinction.  Trees that predated the dinosaurs and survive in pockets in Chile, New Zealand, New Caledonia, Australia, New Guinea and parts of Southeast Asia are being destroyed, with little knowledge of their extreme botanical importance.  Many of these are among the largest trees in the world, rivaling the Redwoods in height and the Sequoias in girth (see Forests chapter).  Others, such as the monkey puzzle tree family, are extremely bizarre in appearance, and may contain important compounds for medicines.  Beautiful primitive flowers, the protea, are also greatly threatened, with many species growing in South Africa.  Tree ferns, palms and hundreds of orchid species are also highly threatened.  The island of Mauritius has a large number of threatened plants, many of which are quite unique.
     Many zoologists and conservationists are now resigned to the rising level of extinctions and believe that, within a century, 80 percent of all species living today will be extinct.  Such predictions may be overly pessimistic, but unless the public is made more aware of the precarious status of a growing number of plants and animals and demands strong action, the prognosis may be fulfilled.

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