"Without any witnesses, or a clear indication that the korora was hit by a vehicle it is unlikely we will be in a position to investigate further," he said.
Last week, locals who believed a car being driven on the beach killed the bird said signs indicating car access was prohibited at Tomahawk Beach had no impact and vehicles endangered both wildlife and people.
Dunedin City Council acting city services general manager Robert West said the council was working to reduce the numbers of vehicles being driven on local beaches.
The city council's focus had been on improved signs and an educational approach rather than enforcement, West said.
At Tomahawk Beach, parking, access and signage had been upgraded to discourage people from driving on the beach.
Community rangers employed by the council and Doc had also been checking for vehicles on beaches, distributing information and undertaking surveys.
"This includes speaking to people about the importance of sharing the beach with endangered species," he said.
An Otago Regional Council spokesman said under the Resource Management Act, public access to and along rivers and the coast was a matter of national importance, but this was balanced with rules to protect the environment and fauna in those areas.
The regional council's jurisdiction over the coastal marine area began at the high-water springs mark, the spokesman said.