The cull will be carried out on seven grassland and woodland sites to conserve grassy ecosystems, according to the government, but opponents say kangaroos are at risk of being wiped out and protesters are travelling from across the country to take part in night time rallies.

After drawing fire from other critics last year for wasting kangaroo meat, 20 per cent of the kill will be processed for baits for wild dogs and foxes.

Territory and Municipal Services Minister Shane Rattenbury said the government would never consider a commercial cull, even though the national commercial quota this year is more than 184,000 kangaroos. Federal statistics show the separate sustainable quota for 2013 is nearly 6 million kangaroos on mainland Australia.

Mr Rattenbury said the ACT cull was too small for commercial gain, and the smallest possible while protecting other flora and fauna in nature reserves.

''The second issue is if we did move to a commercial phase, you almost have to do the cull to feed the process. We certainly don't want to lock in that demand-driven approach.''

Critics have also accused the government of killing or leaving behind hundreds of joeys on previous culls.

Parks and Conservation director Daniel Iglesias said between between March and July the age range of joeys meant they were either independent, or so small they would be with the mother. In those cases, the joeys were killed with a sharp blow to the head.

The cull's timing aimed to avoid when most females had large pouch young or young-at-foot dependent on milk.

Mr Rattenbury said scientific surveys contradicted claims of eastern greys being close to extinction. Instead, they showed some of the highest density of kangaroos per square kilometre in Australia.

''If there was something like a crash in the population those numbers would start to show up. If there was a sense of any sort of endanger or extinction those numbers would show up.''

Mr Iglesias said in the wild, predators kept kangaroo numbers in check, and being herbivores, they could breed rapidly to recover numbers.

''In the ACT kangaroos can increase year on year between 30 and 60 per cent. They'll continue for as long as there's grass. ''The driver for them is food, the check is the predator. We have plenty of food. We don't have the check.''

The shooters had an exceptional strike rate of more than 99 per cent for hitting their target the first time. They worked for other land managers throughout the year, including National Parks and were rigorously tested on macropod identification.

Mr Iglesias said the ACT was the only jurisdiction investing in research for fertility control. CSIRO trials showed some progress on a product from the United States that had rendered deer infertile.

Mr Rattenbury, the sole Greens MLA, said for most of his adult life he had worked to protect the environment.

''I appreciate there are people who find this distasteful.

''I don't think anybody in the ACT government likes the fact this needs to be done,'' he said.

''But for me it is an environmental decision, it is an ecological-based decision.''

Protesters will gather to rally against the impending cull on Thursday, as part of a demonstration organised by Animal Liberation ACT.

The organisation’s Carolyn Drew said she was unsure of how many people would attend the rally, but said she was expecting up to 100 people for night time protests across the capital.

She said the protesters would be a “formidable force” with volunteers coming from Victoria, South Australia and New South Wales after undertaking training.

“That usually involves running around in the middle of the dark,” she said.

“It’s also training in communication.”

Ms Drew also dismissed safety concerns for protesters, saying they wouldn’t take unnecessary risks.

“It’s a necessary risk to go into the parks and find where the shooting is happening,” she said.

“It is risky… but it’s not that they won’t know we’re there.”

Ms Drew said the funding spent on culling operations should be redirected to fencing along roads.

“It would be a simple, constructive solution,” she said.

“I don’t think people in Canberra particularly hate or love kangaroos. I think most Canberrans’ concerns with kangaroos relate to their cars.”

The initial protest will be held outside the ACT Legislative Assembly at 12.30pm.