Tourists flock to Australia to see its koalas, but those taking the ferry to Victoria's French Island are shocked to see hundreds of animals starving in trees stripped of leaves. Tour guide and retired park ranger Scott Coutts told Yahoo News he sometimes feels uneasy about taking visitors to see the island's wildlife.

"It's more than embarrassing, it's shocking," he said. Driving along the island's roads, there are rows of dying trees caused by a combination of drought and overgrazing of leaves by a booming koala population. Pictures show the iconic species clinging to branches without a single leaf to eat.

Locals say hundreds of animals have likely already died, and the survivors urgently need more help.

"They're becoming so weak, they can't even get up the trees and are just passing away," Coutts said. "Tourism is a big thing on the island, and koalas are the main attraction. There won't be that attraction soon," he added.

Koalas are not native to French Island, but three individuals were introduced in the late 1800s. With few natural predators and little disease, their numbers have boomed, and the island off the Mornington Peninsula is now home to thousands.

According to locals, the problem has been spiralling out of control all year, and it's getting worse every day. While there has been a fertility control program on the island since 2008, population growth has continued.

Wildlife Victoria, the state's peak rescue group, said it was "deeply concerned" about the "tragic starvation of koalas" on the island, and that it had offered assistance to the Department of Environment (DEECA).

"This issue continues to highlight the importance of proactive support for our precious native wildlife and the ecosystem they inhabit," it said in an email.

Koalas are listed as endangered in NSW, Queensland and the ACT, but the species is considered abundant in Victoria. However, populations are concentrated in hotspots like French Island, the Otways, and the state's southwest, and conservationists have expressed concerns about their long-term security.

In March this year, numbers inside Budj Bim National Park, north of Portland, had a density of 1 to 1.5 animals per hectare, leading to concerns about ongoing food availability. When a bushfire burned through the park, the situation worsened, and Victoria's government was forced to euthanise over 1,000 animals.

How the government plans to respond to the problem on French Island remains unclear. Its response at Budj Bim proved controversial -- concerns about its methods have been raised at both budget estimates and parliament, and it is currently the focus of legal action in the Supreme Court.

DEECA, which handled the Budj Bim response, directed questions about French Island to Parks Victoria.

In an email, a spokesperson said the two agencies were "actively looking at options to address the situation".

"The koala population on French Island has grown to an unsustainable level and this is impacting both the welfare of the animals and the wider ecosystem," they confirmed.

Concerns about koala welfare on the island were raised publicly in September. Yahoo is seeking further clarification about how the problem has been tackled to date.

Wildlife volunteers are known to have been attending to the dead and dying animals on the island, but Coutts believes the response from authorities has not been urgent enough to control the carnage.

"A lot of landowners have planted koala habitat over the years, and are just seeing it all destroyed. There are acres and acres of private property with dead trees on them with koalas dying of starvation," he said.

"The female koalas have joeys as well, which are emerging from the pouch looking to eat eucalyptus."