Wildlife specialists say oil-coated birds found on Tauranga beaches might not be released for up to six weeks.
By Sunday nine birds - seven little blue penguins and two shags - had been taken to a wildlife centre.
[image:3295:full]Four other birds are known to have died.
They are among the casualties after the 47,000-tonne Rena struck the Astrolabe Reef, about 12 nautical miles off Tauranga, early on Wednesday morning.
The 21-year-old vessel was carrying about 1700 tonnes of fuel and among its cargo are four containers of the hazardous substance ferro-silicon.
The director of the Wildlife Centre in Mt Maunganui, Brett Gartrell, says five of the birds were completely covered in heavy sticky fuel oil and some had ingested it.
Mr Gartrell says the birds need to be washed at least twice and will need to have their natural feather oils restored before they can be released.
Maritime New Zealand says teams that will treat affected wildlife are also based on Motiti Island.
[image:3292:third:right]Guardians of Maori-owned Tuhua (Mayor Island) are receiving regular updates from the island's caretaker and a helicopter company contracted to check on the oil threat.
The island, about 35 kilometres off the mainland, is run by the Tuhua Trust Board and is used for cultural purposes and to help regenerate endangered species.
Anyone who finds oiled birds or sealife are advised not to handle the animals or attempt to clean them, but to instead phone 0800 333 771.
