Work has restarted on Wellington's most costly cycleway after stopping when four little blue penguins, kororā, were found dead.
One bird was run over outside the site in June.
"While we couldn't be certain of the cause, we could not rule out the project as being a factor," Waka Kotahi said - three more were found inside the site last month.
The alliance building the $300 million path from Ngauranga to Petone was still investigating how it happened.
In the meantime, the project had introduced extra protections such as larger signs around where the kororā live, the transport agency said.
There would be more surveillance and checks, and more training of workers on following the rules.
"The project team is taking every step it can to better protect the kororā.
"It is essential the consents in place to protect the birds are rigorously observed."
It had no estimate yet of what the stopwork had cost and it did not say who would cover the costs.
The project was working with DOC and the regional council on improving things further.
If an active nest or moulting penguin was detected, work would stop in that spot and "not re-start until nesting or moulting is complete".
"Any nest found will be cordoned off and a dedicated exclusion zone created."
It consulted experts before beginning work, and changed parts of the rocky shoreline to discourage them from nesting in construction areas.
'Steps are taken to monitor each penguin's movements after relocation to see if they return to the proposed construction zone."
The Te Ara Tupua Alliance comprises of 10 partners including iwi, councils and contractors.