Species that can only survive within a narrow range of environmental conditions and whose disappearance from an area is an index of pollution or other environmental change. Those species which rely on specific habitat conditions that are limited in abundance, restricted in distribution, or are particularly sensitive to development. Plant or animal species which are: Federal listed or proposed threatened or endangered species, or candidate species; bird species protected under the Migratory Bird Treaty Act; species protected under State endangered species laws and regulations, plant protection laws and regulations, Fish and Game codes, or species of special concern listings and policies; or species recognized by national, state, or local environmental organizations (e.g., the California Native Plant Society).