Many species that are vulnerable to oil are wide-ranging, and may be present over large areas at any time. These species can be especially vulnerable at particular times and places. Animals and their habitats tend to be most at risk from oil spills when, for example, Many individuals are concentrated in a small area, such as a seal haulout area or a bay where waterfowl concentrate during migration. Early life stages are present in certain areas, such as seabird rookeries, spawning beds used by anadromous fish, or turtle nesting beaches. Oil affects areas important to specific life stages or important for migration, such as foraging or over-wintering sites.
Specific areas are critically important for propagation of a species.
A particular species is threatened or endangered. A substantial percentage of an animal or plant population is likely to be exposed to oil. ESI maps show where these most sensitive species, life stages, and locations exist, but don't necessarily show the entire area where members of a sensitive species occur. The numbers of species members present at that location. Estimated start and end dates for specific breeding activities.