Rehabilitated birds are able to return to normal behaviours after an oil spill, according to a Massey University study in the wake of the Rena disaster.

The researchers say the findings justify the costs of oiled wildlife response worldwide.

Five years ago this month, the cargo ship Rena ran aground off the Bay of Plenty coast, spilling more than 300 tonnes of heavy fuel oil.

As part of the response, 383 Little Blue penguins were captured, cared for and released back into a cleaned environment.


Previous research had shown these rehabilitated penguins to have similar survival rates to unaffected birds in the area.

In a study published in the Marine Pollution Bulletin, scientists from Massey's Wildbase Oil Response Team evaluated the foraging behaviour of eight rehabilitated birds.

They used tracking devices and compared the behaviour with that of six unaffected birds.

Paper co-author Dr Louise Chilvers says they found rehabilitated and non- rehabilitated birds were diving to similar depths and in similar locations.

By analysing the carbon and nitrogen levels in the birds' feathers, they were also able to show the penguins were feeding on similar prey.

Dr Chilvers says it is also necessary to evaluate the behaviour of animals affected by oil spills, not just the overall survival rates.

Along with other research over the last two years, the study indicated the birds were finding and eating enough prey to gain the nutrients and energy they needed to survive and reproduce at similar rates to other populations of little blue penguins in Australia and New Zealand.

"Opponents of oiled wildlife response argue that rehabilitation is an expensive anthropogenic need to lessen the stress of oiled wildlife and has very little or no conservation value," Dr Chilvers.

"This research shows rehabilitation and intervention is effective both in the short and long term."