More than a million kangaroos are expected to be killed in Australia this year as the country launches a mass cull of the creatures in an effort to protect endangered grasslands and wildlife.

Wildlife groups have criticised the plans and warned that the illegal killing of the creatures by farmers and hunters, combined with the government-sanctioned cull, could see their numbers rapidly deplete.

An Office of Environment and Heritage spokesperson for the New South Wales government insisted the quotas were “sustainable in the long term”.

But Brad Smith, secretary of the Upper Hunter Valley Wildlife Aid group, told The Independent that he feared kangaroos could soon become extinct if the level of culling continues.

“If you take into account the numbers of kangaroos shot each year and the numbers hit and killed by cars, it’s running into millions and millions per year," he said.

Australia’s national parks allocate “tags” to property owners who wish to cull kangaroos on their land, which they are then required to attach to any kangaroo they shoot as a way to mark that it was a legal kangaroo shooting.

But this doesn’t happen often enough, said Mr Smith, who has been running the group from his home in southern Australia for 10 years.

“A person who wants ’roos culled from their property has to contact the national parks, who will then give them a tag for every kangaroo they are allowed to shoot. But that very rarely happens, not nearly enough,” he added.

Around 160 joeys are rescued by Upper Hunter Valley Wildlife Aid each year from their dead mothers’ pouches (Upper Hunter Valley Wildlife Aid)

“Often farmers will just shoot them for their dogs to eat. It’s illegal but if it’s on a farmer’s property, who’s going to see it? You’ve got all sorts of people who just go out and shoot away, killing as many as they can.”

Upper Hunter Valley Wildlife Aid works specifically to rescue and rehabilitate injured or orphaned kangaroos and other animals, and Mr Smith and his wife are currently caring for 13 joeys in their home.

The group rescues around 160 orphaned joeys each year and receives around 2,000 calls during that time from people who have found the young creatures in need of rescuing.

Mr Smith explained that they are rescued in “all sorts of situations”, including where their mothers have been hit by cars and caught in fences — as well as after they have been shot dead.

The Smiths are currently caring for and rehabilitating 13 orphaned joeys in their home (Upper Hunter Valley Wildlife Aid)

“When they shoot a kangaroo they either leave the joey in the pouch to die — where it will eventually starve, freeze, cook or get eaten by some sort of predator — or they just grab the animal by the ankles and smash its head on a rock or a tree,” he said.

“That is classed by the national parks as the humane way to kill a joey: blunt force trauma to the head. And joeys don’t even count in the numbers that are allowed to be killed.”

Mr Smith said he believed around 60 per cent of joeys born in Australia today do not reach adulthood, with most deaths caused by human actions.

Joeys being fed after being rescued from their dead mothers’ pouches (Upper Hunter Valley Wildlife Aid)

Official statistics show that more than 1.5 million kangaroos were killed in 2015, and while the figures for 2016 are not yet available, it is estimated to be in a similar region. But Mr Smith believes the true numbers are higher.

“There are official stats, but they don’t know the full number killed each year because it’s so often done illegally,” he told The Independent.

Mr Smith says around 60 per cent of joeys born in Australia today do not reach adulthood, with most deaths caused by human actions (Upper Hunter Valley Wildlife Aid)

“I know that in some parts of the country kangaroos are in plague proportions, while in other parts of the country they aren’t. But this doesn’t stop shooters shooting.