Wild sows have been caught on camera in a native reserve in Christchurch's Port Hills.
These unwelcome new residents are making a big mess.
The Summit Road Society look after a native bush reserve near Gibraltor rock and they say they've recently seen an influx of both fallow deer and wild pigs roaming the area
"They've got a good food source and they've just grown there's been no pressure on them and now we've got quite a problem," said Summit Road society member Greg Gimblett.
- Pigs illegally released onto Northland conservation land
- Family poisoned by eating wild boar will be covered by ACC
A walk through the reserve has revealed the extent of the damage the pigs rooting is having on the undergrowth of the native forest.
"All of the understory is gone essentially and it'll take a long time for that to recover," said Gimblett.
The Christchurch City Council says it's aware of the problem up here as there have been reported sightings from both rangers and the public.
But, because council hasn't done a head count, it doesn't know the numbers it's working with.
The Society suspects there could be at least a hundred of both species. That's why it's put deer fencing up around the perimeter of the 160-acre reserve and are now working on a control programme to reduce the feral animal population.