Leisure Island's little blue penguin colony has taken a devastating blow one week out from the second anniversary of the Rena grounding on Astrolabe Reef.

Most of the colony's eggs have been destroyed and numerous chicks killed by stoats, and suspected dogs, says Mount Penguin Monitoring Group leader Dave Richards.

Julia Graham inspects one of the little blue penguins on Leisure Island.

Group members Julia Graham and Bekki Richards discovered the raided nests last weekend during a regular monitoring of the island's penguins.

'Stoats and possibly a dog have basically wiped out the entire colony's eggs and killed most chicks that had hatched,” says Dave.

Of the 24 burrows inspected, 11 had been abandoned with the eggs missing, and one nest had two dead chicks inside, he says.

'It's very devastating. We've spent hours and hours out there every week with extensive monitoring.”

The Mount Penguin Monitoring Group was formed in the wake of the Rena grounding in October 2011 and worked every night during the peak of the oil spill to rescue hundreds of oiled birds.

Since then, the group has been monitoring the recovery of the local little blue colony on Leisure Island, Rabbit Island and Mount Maunganui, two-four times a week.

This involves hours of checking penguins' weight, condition, behaviour and breeding patterns to determine whether the oiled birds recover long-term from 2011's environmental disaster.

The group estimates about 200 little blue penguins reside on Leisure Island, and 800 around Mauao.

Dave says the results have been 'very positive”.

'The oiled birds have been breeding, and the whole clean-up of the birds has been very successful. 'It's all been very worthwhile, unfortunately this has happened.”

While it is a severe knock-back, Dave believes the colony will bounce back.

'The good thing is that the birds will most likely nest again, they've got time to.”

Little blue penguin breeding season traditionally runs from August to January, but the residing threat from pests and pets remains.

Dogs are banned from Leisure Island, and Dave says almost every time the group checks the nests they have to ask people to remove their dogs.

'It's because they don't understand, it's about educating. There are penguin nests out in the open and dogs can get into them, and often people don't realise they're actually walking on top of the nests too.”

Aside from residents' dogs and cats, stoats are the biggest threat to the little blues – and it is an issue the group is tackling first-hand.

Following last weekend's attacks, intensive trapping is now underway by Tauranga City Council, says Dave.

'Up to this stage most trapping and pest control has been out of our hands. This is changing soon and we will be more intensely involved (with TCC's pest prevention) in the future.

'There is a new pest regime coming into play really soon, across the whole of Tauranga so there will hopefully be more focussed pest control happening on the Mount and Leisure Island. We've had a gutsful of this happening, so we need to stand up more rather than just lie and except it.”

Dave credits TCC for its eagerness to help solve the issue.

'They are working really well with us, they're helping us, and it's a very good relationship. We are very positive about what's going to be happening in the future.”

The second anniversary of the Rena disaster is on Saturday, October 5. The penguins that suffered in the oil spill are being remembered with a stone sculpture by artist Peter Cramond.

Dave and other members of the monitoring group will attend the sculpture's unveiling at Mount Maunganui Main Beach on Saturday, where Julia will speak on the penguins' progress.