New challenges

Introduced species often threatened in their old habitat

Non-native species introduced by humans are among the main causes of global species decline - they were partly responsible for 60 percent of the species that have become extinct worldwide in recent decades. In the picture: Mouflons

(Bild: stock.adobe.com/vasekkkk - stock.adobe.com)

A study involving the University of Vienna shows that invasive species are often themselves threatened with extinction in their old homeland.

The influx of introduced species and their advance into newly developed regions often puts pressure on native competitors or spreads new diseases - thus endangering biodiversity.

"Nature conservation paradox"
The work carried out by a team led by Viennese ecologist Franz Essl and Lisa Tedeschi highlights "a conservation paradox": in view of the threat posed by invasive species as well as their own, the question now arises as to whether non-native species should also be protected in their new home.

The study was published in the journal "Conservation Letters".

(Bild: conbio.onlinelibrary.wiley.com)

Until now, it was not known how many non-native mammal species - in Central Europe these include species such as the Norway rat, the mouflon or the mink - this paradox applies to.

Mink

(Bild: imaton - stock.adobe.com)

36 of 230 invasive mammal species affected
Currently, a total of 230 non-native mammal species have been introduced by humans into new areas worldwide and have settled there permanently. The researchers were able to show that 36 of the non-native mammal species are threatened in their original habitat.

Most of the endangered species in their native range originate from tropical Asia, which in many cases is a consequence of massive rainforest destruction and overhunting.

The crested macaque, which is endangered in its native habitat and whose population has declined by 85 percent in its natural range on Sulawesi since 1978, has spread to other islands in Indonesia and is forming stable populations there.

(Bild: Michael Geyer Photography – stock.adobe.com)

It has been shown that non-native populations can play a key role in the survival of endangered species - especially when there is a high level of threat pressure in the native area.

New challenges for animal welfare
Non-native populations can also have a negative impact on other species. The main focus must therefore continue to be on the protection of species in their native range.

However, it is likely that "in the future, there will be more species that are threatened with extinction in their native areas and have better chances of survival in their new range", says Essl. This presents nature conservation with the difficult task of weighing up the opportunities and risks.