The Rena oil spill clean up has reached another milestone with the last group of birds being released into the wild.
Seven little blue penguins oiled after the container ship Rena crashed into Astrolabe Reef off Tauranga, have been released near Motiti Island, Maritime New Zealand says.
Hundreds of birds have been treated and more than 2000 found dead since October.
Teams have only found five oiled birds in the past month, National Oiled Wildlife Response Team coordinator Kerri Morgan says.
"This is really reassuring as it shows us that the amounts of residual oil in the environment are not having a significant effect on wildlife."
Two birds remain in treatment, which will be released, and wildlife teams don't expect to release more groups of birds, she says.
National On Scene Commander Mick Courtnell says wildlife teams will no longer be at the incident command centre, but will still follow up reports of oiled birds.
"The fact we have got to the point where we can count the number of affected birds left in care on one hand is a real milestone in the response and recovery operation."
About 65 people continued to check for and clean up residual oil, he said.
"It's important to recognise that while the bulk of the oil is safely off Rena and the bulk of the oil spilled has been cleaned up, we still face a threat from the wreck, in the form of a few pockets of oil that the salvors can not reach."
Tens of tonnes of oil were estimated to remain on Rena and another spill could reach the shore and affect wildlife, Mr Courtnell said.
Meanwhile, salvage teams have so far removed 514 tonnes from Rena and 70 tonnes from the surrounding land and sea.
Two vessels continued to search the sea floor for missing containers with sonar sweeps.
NZN