But environmental groups have urged caution, saying nonnative species can bring problems, including different kinds of diseases and parasites.

The main two threats to the species' survival are mining and nonnative species.

By contrast, a nonnative species is one that is found outside its previously observed range.

Swamp eels survive even in the dry season when other nonnative species normally die.

The controversy shows the problems that can arise when a nonnative species arrives in an ecosystem.

It is a nonnative invasive species in parts of northern America.

His research showed that the number of nonnative species varied from habitat to habitat.

The carrying capacity of the nonnative species remains variable while adapting to their new environment.

Over the decades, there is an increase of nonnative species.

Finally, humans released of nonnative species which competed with the native birds for food, water, shelter and a place to raise their young.