Naturalisation (or naturalization) is the ecological phenomenon through which a species, taxon, or population of exotic (as opposed to native) origin integrates into a given ecosystem, becoming capable of reproducing and growing in it, and proceeds to disseminate spontaneously.
For example, northern white cedar is naturalised in the United Kingdom, where it reproduces on its own, while it is not in France, where human intervention via cuttings or seeds are essential for its dissemination.
[citation needed] Two categories of naturalisation are defined from two distinct parameters: one, archaeonaturalised, refers to introduction before a given time (introduced over a hundred years ago), while the second, amphinaturalised or eurynaturalised, implies a notion of spatial extension (taxon assimilated indigenous and present over a vast space, opposed to stenonaturalised).
For instance, the African sacred ibis (Threskiornis aethiopicus) escaped in 1990 from an animal park in Morbihan (France), gave rise to an eradication campaign in 2008.
In 2013, however, the CNRS stated that this bird species is not a threat in France, and may even promote Eurasian spoonbill and limit the development of the invasive Louisiana crayfish.