"It's meant to be a safe space for little chicks and it's not so it needs to be rectified as soon as possible.
"If it's a female that has swum to the island, we've got a problem."
Stoats have kits 9-10 months after impregnation.
Described by the Department of Conservation as "voracious and relentless hunters", they are the number one predator threat to kiwi chicks. Dogs are the number one controlled predator threat to adult kiwi.
Williams says before being aware of stoats on Motutapu, Kiwis for kiwi had released two Coromandel brown kiwi chicks this season to join the 107 already transferred to the motu.
The chicks were from Kuaotunu, were around 4 weeks of age and weighed 450 grams at release.
The charity sent but a kiwi-certified dog and handler sent to the island on New Year's Eve only found one. It was flown by helicopter to the National Kiwi Hatchery in Rotorua.
The Kiwis for kiwi operations team decided to remove the chicks as they were most probably under "stoat-safe" weight but a kiwi-certified dog and handler sent to the island on New Year's Eve only found one. It was flown by helicopter to the National Kiwi Hatchery in Rotorua.
Kiwis for kiwi also contracted a predator control expert to check traps on the motu alongside the Department of Conservation and Ngāi tai ki Tāmaki. More traps and field cameras are being installed and the trapping system is being intensified.
Work continues to track down the stoats.
All chicks due for release on to the motu will instead be moved to creches around the North Island where they'll be reared until they're around 1kg.
Williams says she's heartened by the tenacity of Kuaotunu kiwis. Some have been reared at the national kiwi hatchery in Rotorua where staff have told her about the traits of the Kuaotunu chicks.
"They say they can always tell a Kuaotunu bird because they're the wild kids of the bunch, the wild birds, the snarkers, the absolute scrappers. And their plumage is darker.
"I always joke that if we were able to teach them ninja skills it would stand them in good stead."
Four birds originally destined for the motu were relocated to Pūkaha National Wildlife Centre on January 22.
"The safety of kiwi vulnerable to stoat predation is of utmost importance to Kiwis for kiwi and it is thankful to everyone who continues to protect this precious taonga on the mainland as well as on islands."
Volunteer trappers operate around Coromandel-Hauraki, from Paeroa and Ngatea to south of Whangamata and up to the tip of the peninsula to rid areas of predators to kiwi.
The goal is to link the successfully trapped areas so kiwis can thrive.
"We are a peninsula bounded on three sides [by water] so if we want to make it a really unpleasant place for predators.
"We're using predator free islands to gather all the genetic stock while the mainland gets co-ordinated and connects its safe places.
Williams said it would be a battle but was possible to have kiwi thriving throughout the Coromandel.
"I really believe in the plan."
• At 178 million years old, pest-free Motutapu is one of the oldest land masses in the Hauraki Gulf. The island was intensively settled by Māori, it hosted massive Victorian picnic parties, and was a base during WWll. Now, after the world's largest island pest eradication programme, it's a fine place to see native birds including the rare tieke. Ngāi Tai ki Tāmaki and DoC are focused on restoring the mauri on the island.
Owners urged to train pets
DoC and community conservation groups are offering kiwi aversion training this summer, and dog owners can contact the Kauaeranga Visitor Centre on 07 867 9080 to book into a session. The training takes about 10 minutes and is free.
DoC and kiwi protection groups are urging dog owners to have their pets trained to avoid kiwi, after a spate of recent deaths of the national icon on the Coromandel.
Mailee Stanbury, a DoC biodiversity senior ranger, says there have been recent reports of dead Coromandel brown kiwi discovered in three locations — Tairua, Whenuakite and Matarangi. The deaths are thought to be the result of attacks by dogs. The birds killed at Tairua and Whenuakite have been confirmed as the victims of dog attacks through DNA testing.
Dog owners cannot take their animals on public conservation land in Whenuakite. It is the only completely protected kiwi zone in DoC's Hauraki District.
"We need dog owners to keep their animals under control at all times — tied up or contained at night," Mailee Stanbury says. "Dog owners can also do the right thing to protect our precious kiwi by arranging for their pets to have kiwi avoidance training. "
