Wallabies are on the move.
Once confined to the Hunter Hills, they have now spread to the Mt Dobson area.
In June, a 1080 bait operation was run by the Department of Conservation to control the spread.
The exact number of wallabies culled in the operation was unknown, Environment Canterbury biosecurity team leader Brent Glentworth said.
"With a 1080 pellet operation the exact number of wallaby controlled cannot be determined as wallaby consume the bait and die two to four hours after eating a lethal dose."
Numbers have also been rising during the past two decades and have spread within and outside the containment area, which includes the Two Thumb Range, Albury Range, Kirkliston Range, Grampian Mountains, The Hunter Hills and Kakahu Bush.
Glentworth said wallaby numbers were measured on a predetermined scale which uses descriptors to indicate animal abundance.
At high densities, wallabies can have significant adverse environmental effects, according to ECan.
These include the prevention of regeneration of native bush, depletion of forest understorey and possible impacts on water quality and increased soil erosion.
- The Timaru Herald