Major invasive species: task of seeing in original habitat

I wrote a post about finding well-known urban cockroach species in their original habitat.

Thinking about rats just now, I feel this is a topic that can be broadened to other species.

If you have personally observed a worldwide invasive species in its original habitat,

or if you know of historical records of such observations,

would you like to share?

Two easy examples:

Rock Dove, the ancestor of the feral pigeon, still occurs as a wild species along parts of the Scottish coast. I learnt about this in Collins Bird Guide.

Lionfish are native to the Indian Ocean.

Two hard examples:

The domesticated rat (Rattus norvegicus) probably originates from Mongolia, but I can’t find a suitable example from there on iNat. The records from nearby parts of Russia and China are mostly urban, with one record of a carcass in a field of crops and another record of a carcass near a remote lake. A live example would have been cool!

Also, I still haven’t got a definitive answer for those cockroaches. It might be time for me to email an expert, haha.

Cheers everyone!


Pigeons are interesting birds. Its origin is in western asia, parts of europe probably not Scotland and parts of Africa. It is associated with human civilization.
Lion fish are spectacular fish. That’s why people want to keep them in an aquarium. But saltwater aquarium requires a lot of maintenance. I’m at where Lionfish is supposed to be. I’ve not spent enough time at reefs or open water, never seen them in the wild, only in aquariums. From youtube vids, Lionfish seems to be so abundant in Central America, that they are trying hard to control them.
The rat is mentioned as originated from the far east. Trading ships brought the rat from the far east to europe and to everywhere on earth. Associated with the plague that killed lots of people in the middle ages. I’ve never been to Mongolia. The exact origin of the brown rat is not clear. From articles, it is China which has a very long history of civilization. The rat evolve with humans growing grains. Its range may be limited by deserts and mountain ranges. In natural places of asia, there exist species of rat that are different from the urban rats.
I know the local spotted doves has reached America. The Javan mynahs has reached Australia. The spotted dove might be from further north, like maybe Thailand, IndoChina and present on coastal beaches. Humans brought the doves to other places on earth as pets.
I personally will share a picture of creatures. because it is there. The implications is some naturalists are wired to think in a certain way, like the species is invasive, as this platform creates a red ! alert symbol that implies it is non-native.