Southland residents have been urged to immediately call either Environment Southland or the SPCA if they spot wallabies in the region.
The advice came after a North Invercargill resident was shocked to see one of the marsupials in her neighbour's backyard at the weekend.
Environment Southland biosecurity manager Richard Bowman said the woman called the SPCA after she discovered it was a wallaby which had been disturbing her dog.
She had not previously been aware of the ''unexpected visitor'' and did not know where it had come from.
It is understood a Southland resident called Environment Southland just over a week ago believing they may have spotted a wallaby; however, it was not located.
The SPCA was contacted at the weekend to attend the North Invercargill property where the young wallaby - estimated to be about 8 months old - was found.
Mr Bowman said it was ''reasonably tame'' and it had possibly been kept as a pet before escaping.
After being captured by the SPCA, it was transported to a wildlife park in South Canterbury, which accepts orphaned animals.
Mr Bowman said under Southland's regional pest management strategy wallabies were considered pests so nobody could possess or sell one within the region without a permit.
It was also against the rules to transport a wallaby into or within the region and anyone who saw one must report it to Environment Southland, which had the power to prosecute people in possession of wallabies, under the Biosecurity Act.
The Ministry of Primary Industries listed wallabies as an ''unwanted organism'' so it was illegal to sell, distribute, propagate or possess one.
''It's quite possible that someone's been in South Canterbury and they've shot a female with a joey in its pouch and they've brought it home ... [But] they have to realise it's not legal to keep wallabies in our region,'' he said.
While wild wallabies had not yet been identified in the region, if a population was to establish in Southland it would have a ''significant economic and environmental impact''.
They caused problems in South Canterbury, damaging native forests and competing with cattle and sheep for pasture. They were capable of reaching ''very high population numbers''.
SPCA Southland chairwoman Rachel Hucklebridge said the wallaby was one of the more unusual calls they had received and although it was very cute, she was very aware of its pest status in Southland.
