Red-necked wallabies have been introduced to several other countries, including New Zealand, the United Kingdom (in England and Scotland), Ireland, the Isle of Man, France and Germany.

[4] Red-necked wallabies are distinguished by their black nose and paws, white stripe on the upper lip, and grizzled medium grey coat with a reddish wash across the shoulders.

In Tasmania and coastal Queensland, their numbers have expanded over the past 30 years because of a reduction in hunting pressure and the partial clearing of forest to result in a mosaic of pastures where wallabies can feed at night, alongside bushland where they can shelter by day.

A recent study has demonstrated that wallabies, as other social or gregarious mammals, are able to manage conflict via reconciliation, involving the post-conflict reunion, after a fight, of former opponents, which engage in affinitive contacts.

Captive animals maintain their breeding schedules; Tasmanian females that become pregnant out of their normal season delay birth until summer, which can be anywhere up to 8 months later.

There are also other sightings frequently spotted in West Sussex and Hampshire and recently YouTuber 'Wildlife With Cookie' found a population in an unknown part of England not associated with the previous mentioned locations.

[12] There is a small colony of red-necked wallabies on the island of Inchconnachan, Loch Lomond in Argyll and Bute, Scotland.

[15] A 2023 study by the Manx Wildlife Trust using drone and thermal technology resulted in the first accurate count of the red-necked wallabies in the Ballaugh Curragh Area of Special Scientific Interest and Ramsar site.

Two nocturnal surveys, carried out across 400 hectares of the Ballaugh Curragh over two consecutive nights, gave an average number of 568 wallabies with a density of 140 per km².

As the survey site included surrounding agricultural land, it is thought the density would be higher when the wallabies retreat into the wet woodland during the day.

[17] In France, in the southern part of the Forest of Rambouillet, 50 km (31 mi) west from Paris, there is a wild group of around 50–100 Bennett's wallabies.

[19] In October 2014, three captive Bennett's wallabies escaped into the wild in northern Austria and one of them roamed the area for three months before being recaptured, surprisingly surviving the harsh winter there.