An AZE site must meet all three criteria: •Endangerment. An AZE site must contain at least one Endangered (EN) or Critically Endangered (CR) species, as listed by IUCN - World Conservation Union.
•Irreplaceability. An AZE site should only be designated if it is the sole area where an EN or CR species occurs (for EW, where it occurred), or contains the overwhelmingly significant known resident population of the EN or CR species, or contains the overwhelmingly significant known population for one life history segment (e.g., breeding or wintering) of the EN or CR species.
•Discreteness. The area must have a definable boundary within which the character of habitats, biological communities, and/or management issues have more in common with each other than they do with those in adjacent areas.