A pregnant kororā or little blue penguin which was found dead at Pūtiki Bay several weeks ago was likely attacked by a dog, the Department of Conservation (DOC) says.
Concerns were raised about the poor health of the kororā by tangata whenua and native bird experts on Waiheke Island when it was found near the Kennedy Point marina construction zone.
DOC has since warned dog owners can face penalties and/or prosecution for their dogs causing injury or death to wildlife.
Investigations team lead Dylan Swain said although DOC staff are still waiting for genetic test results, evidence indicates a dog was responsible.
"Necropsy results do show the likely cause of death was a result of a dog attack, and we have received an image of a dog in the area in the early morning of the day the kororā was found. We are encouraging anyone with more information to come forward.
"Ground dwelling native birds don't naturally co-exist with dogs, and they can't escape easily - it takes just a second for a dog to cause a fatal injury to a penguin, which is what we have seen here."
DOC is encouraging anyone with further information about wildlife crime to contact them on the department website.
Karen Saunders from Waiheke Native bird rescue nursed the sick kororā when it was rescued and said she wasn't surprised a dog attack had been linked to the penguin's eventual death as they had initially considered that possibility but needed further evidence.
She believed stress may have also been a contributor to the bird's death as it was severely underweight and fatigued when found.
"Often what happens when you're in wildlife rehabilitation is the bird will come in and the dog attack will be the secondary injury.
"For instance, if the bird has been stressed, we all know stress kills, so the stress of the noise, the vibration, the sedimentation that's in the area could have led to this bird being so extremely underweight, because even with an egg it was under 800g and it should have been well over a kilo at that point.
"So the dog attack might have come from that kororā already being quite run down," she said.
Saunders said it was important dogs were on a leash when going anywhere near coastal areas where there may be kororā and for dogs to be kept contained during the night when kororā are active.
In a statement Kennedy Point Marina director Kitt Littlejohn said the findings from DOC directly contradict accusations that the development contributed to its death.
"Robust procedures are in place to ensure the kororā at Kennedy Point are protected during construction of the marina. All works are being undertaken in accordance with a detailed Kororā Construction Monitoring and Management Plan. Regular surveys of the breakwater wall are being undertaken by ecologists to collect information around kororā activity and to monitor their welfare during construction of the marina. Works are also being closely monitored by council and DOC.
"The company is aware of the public interest in the kororā at Kennedy Point and remains committed to providing regular and transparent updates. There continues to be a great deal of misinformation being deliberately spread around this issue, and we would encourage anyone who has concerns for the kororā to ensure they have all the facts before jumping to conclusions," he said.
The developer said recent inspections have confirmed the breakwater continues to be used by the kororā and they are breeding successfully.
"It is also very disappointing that the Kennedy Point beach and foreshore is a 'dogs on leash at all times' area under council bylaws, yet off-leash dogs are regularly observed in the area by the company's on-site personnel.
"For the sake of the kororā, please keep your dogs on leash when at Kennedy Point," Littlejohn said.