Numbers of pests and game animals are rapidly increasing in parts of the country, regional councils report.
Successive mild seasons, reduced hunter pressure and growing resistance to rabbit haemorrhagic disease (RHD), is leading to increased numbers of deer, goats, wallabies and rabbits in many areas.
The Otago Regional Council’s (ORC) environmental implementation manager Andrea Howard says rabbit density differs across the region, but remains high in parts of Central Otago.
“Several factors influence rabbit populations, including lack of consistent control – and secondary control – by landowners, the naturally reducing impact of introduced viruses, climate change, land-use change, urban spread into historically rabbit-prone rural land and associated reduction in available control tools,” Howard said.
The council is monitoring its northern border for any southern incursion of wallabies from South Canterbury.
Environment Canterbury (ECan) principal biosecurity adviser Laurence Smith says rabbits are a localised problem in areas such as the Mackenzie district.
In response to anecdotal information that feral deer numbers are rising, he says the council is planning to meet with the community and relevant agencies to discuss the problem.
The National Wallaby Eradication Programme (NWEP), which is led by the Ministry for Primary Industries and implemented by ECan, has targeted over 320,000ha in its first year, using a range of control methods.
“A search and destroy programme of this nature and scale is a historic first for NZ,” Smith said.
Eradication will require new technology and innovation.
“The complexities and problems of effectively dealing with a largely secretive, nocturnal, highly mobile vertebrate pest with the currently available toolbox, cannot be understated,” he said.
Environment Southland animal biosecurity team leader Dave Burgess says the growth of dairying in the province and the shift to long swar has made the habitat less favourable for rabbits.
Deer and goat populations appear to be increasing and the council is concerned wallabies may spread south.
The Waikato Regional Council reports wallabies are still in low numbers in the Waikato, but is concerned about spread from the Bay of Plenty.
The Hawke’s Bay Regional Council’s manager of catchment services Campbell Leckie says numbers of rabbits, feral deer and goats have been increasing over the past five years.
“Increasing pest numbers highlight a risk or challenge, which needs a reassessment of the current management and community priorities for pest control,” Leckie said.
Rabbit numbers are increasing due to a dry climate and increasing immunity to RHD.
Bay of Plenty Regional Council biosecurity manager Greg Corbett says wallabies have expanded into the west and southwest of Rotorua.
Consistent control work in the eastern Bay of Plenty has reduced feral goat numbers to a point where there could be local eradication.
“Wallaby spread is largely from natural dispersal, though there is evidence of people either collecting young wallabies and taking them home as pets and/or releasing them,” Corbett said.
Horizons Regional Council natural resources and partnership’s group manager Dr Jon Roygard says the council has been forced to deer-fence three sites it is restoring indigenous ecosystems, to protect them from feral deer.
There are reports of rabbit numbers doubling in some places, with two counts in the Whanganui District increasing by 170% and the other by almost 400%.
The Greater Wellington Regional Council reports anecdotal evidence that deer
have become more populous in the past 10 years.
“They travel large distances and protected populations on private land have now bred up, pushing outside of those boundaries,” Roygard said.
Feral goats are also becoming a greater problem endangering selected environmental sites.
“As with deer, we open our regional parks for goat hunting, with two additional days specifically for targeting goats at the south and eastern ends of East Harbour Regional Park during 2021-22,” he said.
