Code of Federal Regulations Title 50. Wildlife and Fisheries § 50.222.501 Definitions

(a) The term experimental population means any introduced and/or designated population (including any off-spring arising solely therefrom) that has been so designated in accordance with the procedures of this subpart but only when, and at such times as, the population is wholly separate geographically from nonexperimental populations of the same species. Where part of an experimental population overlaps with nonexperimental populations of the same species on a particular occasion, but is wholly separate at other times, specimens of the experimental population will not be recognized as such while in the area of overlap. That is, experimental status will only be recognized outside the areas of overlap. Thus, such a population shall be treated as experimental only when the times of geographic separation are reasonably predictable;  e.g., fixed migration patterns, natural or man-made barriers. A population is not treated as experimental if total separation will occur solely as a result of random and unpredictable events.

(b) The term essential experimental population means an experimental population whose loss would be likely to appreciably reduce the likelihood of the survival of the species in the wild. All other experimental populations are to be classified as nonessential.