Polar bears are a vulnerable species, with a loss of sea ice a leading reason for their population decline.

Photograph by Linda Drake, MyShot
  • On May 14, 2008, the polar bear (Ursus maritimus) was listed as a "threatened species" under the U.S. Endangered Species Act.
    There is more than one reason that the polar bear is listed as threatened. Polar bears live long lives but do not reproduce quickly. A low reproduction rate makes polar bears more vulnerable to a population decline than some other species. Polar bears are also sensitive to changes in the environment, such as melting sea ice. Polar bears use sea ice as a place to hunt for seals and also to mate. If too much ice melts, polar bears may lose their ability to survive. In recent years, sea ice has been melting more and more in the Arctic during summer. This leaves polar bears with less available habitat
  • Term Part of Speech Definition Encyclopedic Entry
    Arctic Noun

    region at Earth's extreme north, encompassed by the Arctic Circle.

    Encyclopedic Entry: Arctic
    decline Verb

    to reduce or go down in number.

    Endangered Species Act Noun

    (1973) U.S. legislation that protects endangered species when they are threatened by human activity.

    environment Noun

    conditions that surround and influence an organism or community.

    habitat Noun

    environment where an organism lives throughout the year or for shorter periods of time.

    Encyclopedic Entry: habitat
    hunt Verb

    to pursue and kill an animal, usually for food.

    mate Verb

    to reproduce or breed.

    reproduce Verb

    to create offspring, by sexual or asexual means.

    survive Verb

    to live.

    threatened species Noun

    organism that may soon become endangered.

    vulnerable species Noun

    level of conservation between "near threatened" and "endangered." Vulnerable is the lowest of the "threatened" categories.