Boaties bringing dogs and cats onto pest-free islands is putting a major nature restoration project at risk, a Northland conservationist says.
DoC and conservation groups are alarmed by reports of people bringing their pets onto the Ipipiri islands, in the eastern Bay of Islands, which have been pest-free since 2009 and are home to many rare species.
Urupukapuka and Moturua islands are particularly popular with visitors but are also teeming with native birds, reptiles and insects.
Pets aren't regarded as pests but are barred from the islands because of the risks they pose to wildlife.
Project Island Song coordinator Richard Robbins put the increase in dogs and cats down to more boaties travelling to the Bay because of the closed borders.
''We're all pet lovers but there are good and bad places for them,'' he said.
''A huge amount of work has gone into these islands. We want people to visit and enjoy them, but pet owners may not understand the consequences of bringing dogs and cats, even if they see them as being under control.''
It also posed a risk to the future of the project, he said.
''If it's perceived that we have a problem with dogs and cats coming ashore there are certain species we just won't be able to reintroduce, like tuatara and takahe.''
• All pets are banned from public conservation land in the Ipipiri islands of the eastern Bay of Islands. That includes Urupukapuka, Moturua, Motuarohia, Waewaetorea and Ōkahu.
• Boaties and daytrippers should check their vessels, bags and camping gear for stowaways such as rats, mice, skinks and ants. Take extra care to clean gear if you have argentine ants or plague skinks where you live.
• If you bring food to the islands make sure it's in sealed containers, not open bags, to avoid bringing rodents.
• If you have pets on board don't moor close to the islands or tie up at jetties.
• If your dog really can't do its business on the boat take it to a suitable place on the mainland, then dispose of the poo properly.
Department of Conservation ranger Helen Ough Dealy said she was increasingly receiving reports of dogs being taken ashore, usually at dawn or dusk, and even cats being walked on beaches or taken on paddleboards.
''These islands are refuges, they are arks, for extremely rare species which have been re-introduced by community groups with a huge amount of dedication. They are trying to save these species from the brink of extinction.''
Even the most domesticated pet had a propensity to chase, or kill, native wildlife. Dogs could frighten shorebirds such as dotterel away from their nests, exposing the eggs to heat or cold.
''And if a dog or cat goes off the beach, up into the reserve, many species can be affected,'' Ough Dealy said.
The latest species to be reintroduced, the wētāpunga or giant wētā, came down to the ground at night to feed, making it easy prey for cats. Native skinks and geckos were also easy pickings.
There were also issues with dog owners not cleaning up after their pets, though that was not specific to the islands.
Signs explaining the rules had been put up on every island and at every wharf and boat ramp on the mainland.
DoC operated daily marine mammal protection patrols in summer, which also kept an eye out for dogs and cats — but rangers couldn't watch every beach, she said.
In 2017 a burmese cat vanished from a boat moored off Moturua Island. Its owners believed it had drowned — the cat was said to be a poor swimmer — but did the right thing by alerting DoC straight away.
DoC launched an extensive search but it was only caught three weeks later in a cage trap baited with canned tuna.
The cat was in good condition suggesting it had been eating birds and lizards. There are no rats or mice on the island.
The search cost taxpayers an estimated $5000. The cat was returned to its owners.
In 2015 another cat, Missy, disappeared off a boat moored off Urupukapuka Island.
The owners didn't tell anyone and the cat was only discovered five months later when it walked into a cafe at Otehei Bay with its paw caught in its collar.
The fact a cat had gone undetected for so long shocked DoC and sparked a shake-up of island biosecurity.
A cat staying on a boat tied up at Moturua last month was reportedly allowed to wander the island all night. Paw prints were found a significant distance from the jetty.
In 2002, when boaties took five ferrets for a walk on Great Barrier Island, a nationwide ban was imposed on keeping ferrets as pets. Like stoats, ferrets are voracious predators.