; and (9) promote ecologically and economically sustainable management in the Northern Rockies Bioregion. 4. Definitions For purposes of this Act: (1) Development The term development means activities that eliminate the roadless and wilderness characteristics of the land and includes ski resort facilities and such activities as roadbuilding, timber harvest, mining, and oil and gas drilling. (2) Greater ecosystem The term greater ecosystem , when used in conjunction with the specific ecosystems protected under this Act, means the ecological land units of sufficient scale to support and maintain populations of large vertebrate species and the other native plant and animal species of the units. These units are comprised of lands which are similar in regards to topography, climate, and plant and animal species. The ecosystems in the Northern Rockies are also defined in terms of the habitat of wildlife indicator species listed as threatened or endangered under section 4(c) of the Endangered Species Act of 1973 ( 16 U.S.C. 1533(c) ), including grizzly bear, gray wolf, bald eagle, and caribou, and have been depicted on maps published by Federal agencies. (3) Northern rockies bioregion The term Northern Rockies Bioregion means the portion of the Northern Rocky Mountains in the States of Montana, Idaho, Wyoming, Oregon, and Washington, so referred to on maps referred to in this Act. (4) Corridors The term corridors means areas that provide connectivity of habitat or potential habitat and that facilitate the ability of terrestrial, estuarine, and freshwater fish, or wildlife to move within a landscape as needed for migration, gene flow, or dispersal, or in response to the impacts of climate change or other impacts. (5) Habitat The term habitat means the physical, chemical, and biological properties that are used by fish, wildlife, or plants for growth, reproduction, survival, food, water, and cover, on a tract of land, in a body of water, or in an area or region. (6) Indian tribe The term Indian tribe has the meaning given