The seven-month-old joey was found on the ground at a property in northern NSW.

The youngster, dubbed Dobby, had fallen while his mother was being harassed by the male, which is typical during breeding season.

A team of Friends of the Koala volunteers rescued Dobby and took him to be assessed by a vet.

Then began a race against time to reunite him with his mother.

About 24 hours later, the volunteers managed to capture her and after several days in care, Dobby made a full recovery and was released back into the wild alongside his mum.

"It's always a special day when we can reunite a mum and joey and release them back into the wild where they can thrive together," International Fund for Animal Welfare rescuer Nicole Rojas-Marin said on Monday.

"Koalas, especially males, face increased threats during breeding season, such as car collisions and dog attacks, because they tend to move around more in search of females to mate and to find new areas to call home, so it's vital we do what we can to help protect them."

It comes as grim figures released by the the Australian Koala Foundation on Monday reveal an estimated 30 per cent of the iconic species have been lost in just three years.

The research showed every region across Australia saw a decline in the koala population and the species is now extinct in 47 of the 128 federal electorates that have, or did have, koalas since white settlement.

Australia's koala populations are now estimated to be between 32,065 to 57,920 - down from 45,745 to 82,170 in 2018.

Australian Associated Press