Remote island's 'miraculous' pest-free transformation

A decade after being declared free of pests Macquarie Island is flourishing with mega herbs, ferns and head-high grasses.

But scientists say ongoing monitoring is crucial to ensure threats to the sub-Antarctic outpost, including new foreign invaders and avian influenza, are kept at bay.

The introduction of rabbits, mice and rats by explorers in the 1800s left the 34km island overgrazed and caused the extinction of two endemic bird species.

It is estimated rabbit numbers on the world heritage-listed island, which is about 1500km south of Tasmania, peaked at 300,000.

An ambitious $24 million eradication project which started in 2007 was declared a success seven years later.

"It really was a miraculous achievement," Tasmania Parks and Wildlife Service manager Andrea Turbett said.

"We were taking (on) three introduced species all at once on such a remote island, mostly in the winter.

"At the time it was a groundbreaking international conservation success."

Ms Turbett has seen parts of the island that were once patches of bare dirt turn green.

"It is flourishing with mega herbs, cabbage, the tussock (grasses) we have all around," she said.

"Ferns that we thought perhaps were a bit doomed ... they're flourishing in a lot of the gullies."

Wildlife biologist Kris Carlyon said the tussock growth had helped solidify slopes, making them much safer for nesting seabirds such as albatross.

Dr Carlyon said erosion caused by rabbits was resulting in land slips and decreasing the breeding success of birds.

"At the time, this reduction of rodents was the largest undertaken anywhere in the world. It was a huge feat to pull off," he said.

Macquarie Island, which is also home to a research station, has strict biosecurity measures including the screening of passengers, contractors and vessels.

Spatial ecologist with the Australian Antarctic Division, Aleks Terauds, described the vegetation as being in great shape.

However, he said targeted monitoring was crucial to safeguarding the island against future threats, including avian influenza which was this summer confirmed as reaching Antarctica.

"One of the reasons we're so committed to long-term monitoring on the island is (that) without this long-term data it is really hard to identify change," he said.

"We've got climate changes on Macquarie Island, we've got the spectre of avian influenza.

"We've got a lot of potential change. Without this monitoring we can't understand what the trajectories are."

A 10-year wildlife monitoring project involving the Australian Antarctic Division and Tasmania's environment department is ongoing.

Macquarie Island is also home to a variety of seals and penguins and is said to support about 3.5 million breeding seabirds.