Feral pigs and donkeys may be more salvation than scourge for ecosystems, study finds

 An unscientific bias against “feral” or “invasive” animals threatens to undercut one of the great stabilizing trends making ecosystems healthier, a new paper argues.

Introduced species such as feral pigs, horses, donkeys and camels represent a powerful force of “rewilding”  — the reintroduction of wild animals into ecosystems where humans had eradicated them — according to a study published Thursday in Science.

...The study argues against widely held beliefs about whether invasive species are harmful — or what Lundgren described as the quasi-religious perception that some species inherently belong in a given landscape and others don’t.

That belief is the driving force behind a wave of expensive and often futile campaigns since the 1990s that eradicate species including feral hogs in Texas, wild horses across the American West and donkeys and camels in Australia.

...The Science study made the case that much of this killing is unnecessary — or even harmful to the ecosystems it is supposed to protect. Introduced species “have partly counteracted” the protracted series of extinctions and general decline among populations of big plant-eating mammals since prehistory, the authors wrote...more