Habitat destruction- is the greatest contributor to the extinction of many species; moreover, impacts to biota from habitat fragmentation is a critical mechanism of driving species to extinction.
Pollution- is the introduction of potentially harmful chemical or physical constituents into the environment, which substances substantially harm individual species metabolisms, or which strongly and rapidly alter a stable historic ecosystem composition. This introduction usually enters the atmosphere, soil or natural water systems of the Earth. Chemical pollutants may interfere with metabolic functions, causing functional impairment or death of organisms.
Cryptic habitats- A special problem arises in the case of cryptic habitats, defined as portions of an ecosystem that are largely hidden from normal investigative view of scientists, or which have components that are not readily discoverable with state of the art research techniques.