Mount Ainslie, Mount Majura, Mulanggari Grasslands, Red Hill, Pinnacle Nature Reserve and Molonglo River Reserve closures for kangaroo cull

The annual cull is due to start next Monday, June 12 and continue until the end of July.

Ecologists calculate 1042 kangaroos will need to be culled to keep the grass at the right level for a wide variety of animals to thrive.

Kangaroos tend to chomp the pasture down and that means insects, birds and other creatures are deprived of their habitat.

Happily for the kangaroos, recent heavy rains mean fewer of them need to be killed this year than in past years. There's more grass for all, so more kangaroos will be allowed to escape the bullet.

"We are not aiming to eliminate kangaroo grazing," ACT ecologist Claire Wimpenny said. "What we are trying to do is to moderate that grazing. If there's too much grazing, there is too much short grass."

The ACT ecologists aim to get grass in the reserves to between five and 15 centimetres, which they estimate is long enough for a range of animals to survive and, ideally, thrive.

The animals which should benefit include the striped legless lizard (which, according to the ecologist, "makes an adorable squeaking sound"), the golden sun moth, the hooded robin and the brown treecreeper.

The number of doomed kangaroos depends on a clever calculation ecologists do.

Officials from the ACT government measure grass height and work out what the height will reach later in the year, given the expected rains. On top of that, a headcount of kangaroos is done in each of the reserves.

In the smaller reserves, the census consists simply of a person walking around and counting the beasts.

In bigger reserves, lines of officials walk through, counting the animals.

And in the biggest reserves, samples are taken and then multiplied across the acreage.

The losers in the lottery are shot in the head to minimise suffering. The carcasses are then disposed of. Some flesh is used for baiting; some skin is used by Indigenous people.

The cull works in tandem with a kind of vaccination program where female kangaroos are injected with a contraceptive, either after being sedated with a dart or contained on the dart itself.

The contraceptive keeps the female joey-free for about seven years. She has tagged ears to indicate her status if she has been felled and the contraceptive injected.

Bren Burkevics, the ACT government's conservator of flora and fauna, agreed that the cull was "a confronting topic", but said it was necessary.

There have been protests in the past, but he said a survey indicated that 76 per cent of Canberrans accepted the cull was necessary.

"I thank all Canberrans for their cooperation and understanding during the reserve closures to allow this important conservation program to be delivered to ensure that the ACT's grasslands and woodland remain vibrant and resilient," he said.

The reserves are to close from 6 pm to 6 am from Sunday to Thursday each week and will remain open from Friday morning to Sunday afternoon. The reserves are Mount Ainslie, Mount Majura, Mulanggari Grasslands, Red Hill, Pinnacle Nature Reserve and Molonglo River Reserve (Kama section).

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