ADAPTATION: biological characteristic that improves the chance of survival of an animal and its descendants

ARABLE: land suitable for cultivation

ARTIODACTYL: the order to which even-toed ungulates belong (e.g., cattle)

BIODIVERSITY: the entire variety of life on this planet

BRACKISH: briny water

CAPTIVE CONSERVATION: keeping small numbers of animals in protective isolation, to insure reproductive success

CARNIVOROUS: meat-eating

CARRION: dead and decaying flesh

CITES: Convention on International Trade in Endangered Species of Wild Fauna and Flora, and international agreement by 132 nations to prohibit trade in endangered wildlife

CLUTCH": the number of eggs produced or incubated at one time

COMPETITOR: a species that may compete for the same resources as another species

CONSERVATION: the management and protection of the natural world

CONSERVATION BIOLOGY: the scientific discipline concerned with the study and protection of the world's biodiversity

DEFORESTATION: removal of forests, usually rapidly and over large areas

ECOSYSTEM: a community of interacting organisms and their physical environment

EMBRYO: an unborn or unhatched offspring

ENDANGERED: in danger of extinction in the forseeable future

ENDANGERED SPECIES ACT (ESA): legislation, passed by Congress in 1973, which protects listed species

ENDANGERED SPECIES LIST: list of species protected under the Endangered Species Act

ESTUARY: place where fresh water enters sea (e.g., at river mouth)

EXOTIC SPECIES: flora or fauna introduced from a different ecosystem; as opposed to native species

EXTINCTION: a species or subspecies is extinct when no living members exist

EXTIRPATED: locally extinct

EYRIES: nests of birds of prey, built high in trees or rock ledges

FAUNA: the animal life of a particular region, geological period, or environment

FLORA: the plants of a particular region, geological period, or environment

FWS: see U.S. Fish and Wildlife Service

GENE POOL: all the genes within a particular population (i.e., total genetic variation)

GLOBAL WARMING: an increase in the earth's average temperature

HABITAT: the environment in which specified organisms live

HYBRID: a cross between parents that are genetically unlike

INBREEDING: mating among individuals that are very closely related

IUCN: International Union for the Conservation of Nature and Natural Resources; publishes Red List

LACTATING: secreting milk

LARVA: a young animal, usually of a species that develops by complete metamorphosis

LICHEN: a plantlike composite consisting of a fungus and and alga

MESQUITE: a thorny leguminous plant found in arid parts of North America

MIGRATING: changing location periodically, usually moving seasonally from one region to another

NATIVE SPECIES: flora or fauna indigenous to an ecosystem; as opposed to exotic species

OVEREXPLOITATION: wasteful killing of a species, usually by hunting or poaching, to well beyond the point at which population levels can be sustained

POACHING: illegally taking protected animals or plants

POLLUTION: contamination or air, water, or soil by the discharge of harmful sobstances

POLYGAMOUS: males having more than one mate

POPULATION: a group of organisms of one species, occupying a defined area and usually isolated from similar groups of the same species

PREDATOR: animal that preys on others

PUPATE: to become a pupa (intermediate stage between larva and adult)

. QUADRUPEDAL: walking on four legs

RAIN FOREST: a dense evergreen forest with an annual rainfall of at least 100 inches (254 cm); may be tropical (e.g., Amazon) or temperate (e.g., Pacific Northwest)

RANGE: the area naturally occupied by a species

RAPTOR: bird of prey

RECOVERY PLAN: a document issued by the FWS that describes ways to protect a species and its habitat

REINTRODUCTION: to place members of a species in their original habitat

RESERVE: an area of land set aside for the use or protection of a species or group of species

ROOKERY: colony of breeding animals (usually birds or seals)

SAVANNA: flat, treeless tropical or subtropical grassland

SPECIES: a group of individuals related by descent, and able to breed among themselves but not with other organisms

SPECIES SURVIVAL PLAN: captive-breeding programs administered by the American Zoological Association

SUBSPECIES: a population of a species distinguished from other such populations by certain characteristics

SYMBIOSIS: the living together of two organisms, frequently for mutual advantage

UNGULATE: hoofed mammal (e.g., horses, rhinoceroses, pigs, hippopotamuses, camels)

U.S. FISH AND WILDLIFE SERVICE: federal agency which oversees implementation of the Endangered Species Act

VIABLE: capable of living, developing, or germinating

VULNERABLE: a species is vulnerable when it satisfies some risk criteria, but not at a level that warrants its identification as Endangered

WETLAND: a permanently moist lowland area such as a marsh or a swamp