Biodiversity Conservation Regulation 2017

Mature individuals are individuals in the wild that are capable of producing viable offspring. The total number of mature individuals excludes individuals that are too young (juvenile), too old (senescent), too moribund (for example, diseased) or otherwise unable to produce viable offspring (for example, due to low population density).

In populations with biased sex ratios, it is appropriate to use a lower value for the total number of mature individuals in a way that takes this into account.

In populations that fluctuate, the number of mature individuals will refer to a minimum number of individuals that are present most of the time (in a time span appropriate to the life cycle and habitat characteristics of the species), and will thus usually be much less than the mean number present.

In clonal organisms, reproducing units may be regarded as mature individuals, so long as they survive independently of one another. However, if clonally reproduced individuals are more limited in viability or dispersal ability than sexually reproduced individuals, the total number of mature individuals may be reduced accordingly to take this into account.

For species in which individuals have synchronous dormant life stages, the number of mature individuals should be assessed during, or projected for, a time when mature individuals are available for breeding.

Re-introduced individuals must have produced viable offspring (after the individuals were re-introduced) before they are counted as mature individuals.

Captive, cultivated or artificially maintained individuals cannot be counted as mature individuals.