Park rangers and conservationists have been working to re-establish the critically endangered species since 2008.

Ranger Ryan Duffy said a program to improve the rock-wallaby population had been running without much success.

He said any offspring born were rarely surviving, until about two years ago when some offspring did thrive.  

“The most recent example of offspring surviving came a few weeks ago when we observed a joey emerge from its mother’s pouch and hop around,” he said.

“Our remotely-triggered cameras got some great footage of the joey coming out – it was really exciting.

“It was heartening to see that not only were offspring being produced but they were surviving as well.”

The Grampians National Park is now home to eight brush-tailed rock-wallabies – four adults and four juveniles.

Mr Duffy said some of the juveniles that were born two years ago had now reached breeding age.

He said the sighting this month meant the program was progressing.

“There have been many hard years, but this was a glimmer of success for the program,” he said.

Mr Duffy said rock-wallabies had been critically endangered for a long time.

He said the Grampians reintroduction program was part of a bigger project that also aimed to secure populations at Mount Rothwell.

“The program involves breeding up stocks of healthy wallabies in capacity and releasing them into the wild,” he said. Many cameras are set up to monitor the colony at all times.

“We are monitoring mortality rates and keeping an eye on reproduction,” he said. “We look at images from the cameras every few weeks.

“All the cameras have lucerne in front of it, because the wallabies love it and are drawn to it.”

Mr Duffy said he hoped the joey sighting was the first step to securing another wallaby population in Victoria.