A single female could introduce a breeding population to an area because they could carry back-up fertilised embryos while rearing a joey.
Otago Regional Council biosecurity and rural liaison manager Andrea Howard said the wallaby kill was bittersweet.
"Obviously we are trying to eradicate wallabies in Otago, so whenever we are able to track one down in the region and destroy it that's a positive," she said.
"At the same time, we would prefer they were not here at all, and the presence of an individual female could suggest more are in the area."
Most of the monitoring work was carried out on the ground but, in the right conditions, thermal imaging from a birds-eye perspective made wallabies easier to spot in difficult terrain and dense vegetation.
"The thermal-equipped helicopter is one of a range of tools for monitoring and tracking wallabies," Howard said.
"The primary method is ground-based surveillance, often using wallaby-detecting dogs, where ground teams cover large areas of land looking for signs of wallabies. In this case, wallaby droppings were found in the area, so we knew where to look with the thermals from the air."
Biosecurity contractors would perform follow-up monitoring in the area to ensure all wallabies were destroyed and council staff would support landowners by offering knowledge and tools to respond to sightings and facilitate surveillance work on their properties.
"We've seen what damage wallabies can do when they become established in an area, so proactive work to identify and destroy them now is essential," Howard said.
"It's important that the community report any sightings to the Otago Regional Council, but we know we cannot rely on community reports alone.
"When populations reach the density that more and more people are starting to see them, they are already breeding and spreading, and we want to intervene before they get to that stage."
- RNZ
