ENVIRONMENT

There is good news and bad news from the world’s leading scientists who study endangered species. Such ups and downs are among the findings of the latest update to the Red List, a guide to the world’s rarest species maintained by the International Union for the Conservation of Nature (IUCN). (National Geographic News)

Use our resources to understand how the IUCN evaluates a species for the Red List.

Discussion Ideas

• The IUCN has strict guidelines for determining the status of endangered species. The organization has five categories of species at risk for population decline (not including species of “least concern” or extinct). Look at our chart, “Endangered Species: Categories and Criteria.” What category of species is the least vulnerable? What category is the most vulnerable?
  • “Near-threatened” species are likely to qualify for a threatened category in the future, but their populations are relatively healthy right now. Emperor penguins are near-threatened.
  • Species that are “extinct in the wild” only survive in captivity, such as zoos or research facilities. The Wyoming toad is considered extinct in the wild.

• Review our chart “Endangered Species: Categories and Criteria.” Under “geographic range,” there are two sub-categories: “extent of occurrence” and “area of occupancy.” What do these categories mean? Is an “extent of occurrence” or “area of occupancy” larger? Read the last two paragraphs on page 3 of our encyclopedic entry on “endangered species” to find out.
  • An extent of occurrence is the larger geographic range. An extent of occurrence is the smallest area that could contain all sites of a species’ population. If all members of a species could survive in a single area, the size of that area is the species’ extent of occurrence.
  • An area of occupancy is where a specific population of a species resides. This area is often a breeding or nesting site.

• Look at the IUCN Red List. Search for each animal mentioned in the Nat Geo News article. Under what category (listed on our chart) are they classified?
  • leatherback sea turtle: Vulnerable
  • okapi: Endangered
  • white-winged flufftail: Critically Endangered
  • Channel Island fox: Near-Threatened
  • black-browed albatross: Near-Threatened
  • black-footed albatross: Near-Threatened

• Read the introduction to our encyclopedic entry. Why do species become endangered? Give an example of each reason.
  • Species become endangered for two reasons: Loss of habitat and loss of genetic variation.
    • Loss of habitat: Development for housing, industry, and agriculture reduces the habitat of native organisms.
    • Loss of genetic variation: Overhunting and overfishing have reduced the populations of many animals. Reduced population means there are fewer breeding pairs. With fewer breeding pairs, genetic variation shrinks.