Koala numbers in south-west Victoria are soaring, with conservationists saying local gum trees are housing more than 100,000 of the furry marsupials.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 6 minutes 25 seconds 6 m Portland artist Brett Jarrett and conservationists on the environmental devastation from koala over breeding ( Cassandra Steeth ) Download 2.9 MB

The Portland Field Naturalist Club estimates the district could be home to at least a quarter of Australia's koalas, and possibly more, but it depends which statistics on koala numbers are used.

The latest Federal Government statistics put Australia's koala population at just over 400,000, but the Australian Koala Foundation say the figure is much lower, at between 40,000 and 85,000.

In the Portland and Mount Eccles regions of south-west Victoria, the koalas are literally eating themselves out of house and home, destroying the natural landscape of the gum trees.

Conservationists believe the region is on track to a situation similar to that in Victoria's Otways region, where increasing koala numbers have caused the animals to starve and led authorities to sterilise them.

They argue if stakeholders act now, they could avoid a koala welfare situation.

Doug Phillips, a conservationist with the Portland Field Naturalist Club, describes the situation as a potential ecological disaster.

"We have a massive over population, with what appears to be no natural breeding control," Mr Phillips said.

"They [the koalas] are browsing woodlands that have been severely depleted historically."

Resident's perspective

Artist Brett Jarrett knows the plight of gum trees all too well.

Artist Brett Jarrett at his Portland home standing with dead and dying gum trees ( Cassandra Steeth )

His family moved back to Portland four years ago for serenity, but instead, Mr Jarrett spends his time shielding trees on his property from hungry koalas.

His property has two dedicated hectares of gum tree woodlands, which previously flourished with bird life and bugs.

It's now bare and dying from koalas over-grazing and Mr Jarrett is rapidly witnessing the ecological demise around his home.

Initially he said it was joyful photographing the koalas on his property for his paintings.

"Then all of a sudden I realised I don't have to search too hard," he said.

He said it was concerning watching trees die.

Trees which you think are okay "just start dying, even with leaves on them," he said.

"If you have a healthy living tree it supports so much."

Instead of Mr Jarrett's trees being home to reptiles, lizards and native birds, he said they now only support a few bugs.

"Other than that, that's it, the tree serves no purpose whatsoever, to any other living thing."

Dead manna gum tree up close, in Portland Victoria ( Cassandra Steeth )

Mr Jarrett estimates his two hectares of woodlands is home to about fifteen koalas, while according to the local conservation group, the sustainable level of koalas is one per hectare.

In one tree alone, Mr Jarrett has three koalas.

"They're not just coming for a social get-together, it's because they're looking for a tree that has good food on it and they'll fight over it to claim the tree."

Wildlife rescuer from the Mosswood wildlife rescue centre, Tracey Wilson, said the situation was close to a disaster and similar to what was happening in the Otways region.

"I think it's a lot closer perhaps than what some people think," Ms Wilson said.

The Portland Field Naturalist Club believes a multifaceted approach is needed to tackle the issue.

"It could include a combination of fertility control and translocation, but importantly the reinstatement of permanent habitat," Mr Phillips said.

The conservation group have organised a meeting in coming weeks to discuss appropriate action.