From 2008 to 2018, the UK has seen almost a hundred red‐necked wallabies, small kangaroos from eastern Australia and Tasmania. This conclusion was reached by a team of researchers, having studied posts on social networks and news sites. Most likely, most of the observations refer to recently escaped captivity, but there is reason to believe that in some parts of the country wallabies have begun to breed in the wild. The results of the study are published in an article for the journal Ecology and Evolution.

Initially, kangaroos lived only in Australia and New Guinea, but thanks to humans biogeographical boundaries have become much less strong. Today, wild kangaroo populations originating from imported or escaped animals have emerged in New York, Hawaii and even Europe. For example, in France, Ireland and Great Britain, you can find medium‐sized red‐necked wallaby (Notamacropus rufogriseus), the natural range of which is located in Tasmania and eastern Australia.

The species probably penetrated into the UK in the first half of the 20th century. A few decades ago in the country, there were two populations of these macropodid marsupials, the ancestors of which were deliberately released or escaped individuals. The group, which lived in the Peak District National Park, was closely monitored, but by 2008 it had disappeared. At the same time, the population from one of the islands on the Scottish lakes of Loch Lomond still exist. In addition, about two thousand wallabies live on the Isle of Man, which is not formally part of the UK.

Holly M. English from University College Dublin and Anthony Caravaggi from the University of South Wales decided to find out whether the wallabies live in other parts of the UK and if so whether they have formed viable populations. Since there is not too much information in the scientific literature on this subject (except for publications about the extinct population from the Peak District), the researchers decided to use another source of information: news media and social networks.

Scientists searched for reports of encounters with the Wallabies in the UK (excluding the Isles of Maine, as well as Jersey and Guernsey, which are also not part of the country) from 2008 to 2018 on national and local news sites, as well as Facebook, Twitter and Reddit. Additional information was provided by environmental organizations.

From this data set, English and Karawaji selected credible cases, i.e. those backed up by photographs or testimonies from several independent observers. In addition to questionable reports, the authors excluded data on escaped from captivity and soon caught wallabies (fugitives left in the wild included in the analysis), as well as two cases of Northern Ireland.

A total of 139 communications were collected, of which 95 were available for analysis. In other words, in ten years the British have met the wallabies almost a hundred times. Almost always these were solitary animals, but twice reported females with a cub in a bag – this may indicate that the species is successfully breeding in the UK (although females may have been pregnant in captivity). Most of the meetings took place in the southern part of the country. Perhaps it is here that the density of marsupials is highest.

According to the authors, this is the first attempt to estimate the number and spread of British wallabies. Encounters with these animals have proved to be quite frequent, but it is difficult to say whether there are more of them. In addition, in most cases it is not clear whether survivors are fugitives or entrenched populations. But in at least a few places in the south of the UK, such as Cornwall, Wiltshire and a protected area on the Chiltern Hills, the Wallabies are found enough often, so if these marsupials are there, it’s probably here.

The species are generally considered a threat to local ecosystems, but it is not yet clear whether the red-necked wallaby poses a threat to British species. So far, there are no signals indicating this. In Ireland and France, they seem to be peacefully coexisting with the local flora and fauna. However, the authors call for a thorough investigation into the wallabies’ impact on British vegetation, as well as their possible role in the spread of infections.