Almost 4000 kangaroos have been killed over the past two years as part of the ACT's annual cull, and some scientists say the "over abundant" status of the native animal is false.

Speaking at an anti-kangaroo culling forum earlier this month hosted by the Animal Justice Party, independent researcher Sheila Newman said the studies relied on to rationalise the cull were "narrow and mechanistic".

"As a scientist myself it's an area where you could do so much and I can't understand how you can have for so many years this remarkable wildlife experiment," she said.

Ms Newman said she was an evolutionary sociologist and that current studies regarding the cull fail to properly comprehend the impact to both the kangaroo species and the kangaroo populations.

She said there was a lack of understanding of the animal's migration patterns, as well as the evolutionary effect which may encourage the native animal to breed younger and faster.

"It would be really interesting to know if we've impacted on them to a degree where we have just wrecked their whole organisation."

Professor David Lindenmayer, a landscape ecologist at the Australian National University, said while he admits "culling animals is not very nice", the lack of modern-day predators, especially dingoes, means the huge number of kangaroos is destroying the ecosystem.

"If there was no culling the first thing is that the biomass of the systems, so the native grass covers, the vegetation structure, many of those things would be significantly damaged," he said.

"We know that because we have measured it. We also know that the things that respond to cover like reptiles, beetles, many of these kinds of animals do significantly badly in these systems where we have very high populations of kangaroos. That's the science. It's been measured."

Professor Lindenmayer said his findings, and also those of his PHD pupils including Brett Howland, are peer-reviewed and conclusive.

"The ecological evidence is compelling," he said. "The science is put together in a very detailed and painstaking way, with literally tens of thousands of measurements over many, many years."

Professor Lindenmayer said there was more to the argument than just the values of a single kangaroo's life.

"Animal welfare people have a particular set of values that values the importance of the individual animal," he said. "There's another set of values that thinks about the conservation of entire ecosystems and all the species that live in them. And how we manage those ecosystems is critically important."

University of Technology Sydney conservation biologist and Director of the Centre for Compassionate Conservation Dr Daniel Ramp said the evidence cited for the justification of culling kangaroos did not stack up.

"We've found that the science justifying the ecological decisions to the killing program did not hold up to the scrutiny based on peer-reviewed scientific literature."

Dr Ramp said the rhetoric that kangaroo populations are out of control is contradictory to the research he and his team have conducted, which suggests their numbers are in fact in decline.

"The problem with this notion of over abundance is that it often gets muddied with attitudes of land use," he said. "In actual fact from purely an ecosystem point-of-view, I have never seen a situation where kangaroos on their own without anything else happening are causing problems where they're out of balance or their not being driven by anything else in the environment. It just doesn't happen."

He said the argument kangaroo grazing has impacted the population of animals such as legless lizards is incorrect because there is evidence the reptile's populations can survive well in areas where kangaroos inhabit, so long as there is no pressure from humans.

"There are populations of legless lizards doing perfectly well in areas where there are lots of kangaroos in Canberra. What we have is a reserve management issue, not a kangaroo management issue."

Dr Ramp is one of a number of individuals to express frustrations this month at the government's lack of transparency involving the policy of culling kangaroos.

"It's been very difficult and I think that's a problem," he said. "We live in a democracy and we should always have open discourse about the decisions we take, particularly when they include killing animals.

"Governments really should be open to listening to good management and good science, and also different attitudes within the community.

"I think you would find that most people don't feel comfortable about the killing of kangaroos. And governments should be listening to that and finding alternate ways to share space."

For Dr Ramp, the behaviour of humans when it comes to sharing the environment with wildlife is unsustainable.

"I don't think this is really a true ecological issue with the way in which kangaroos are out of whack with the environment, I think it is more to do with a socio-ecological understanding of how humans are apart of nature," he said.

"The reason why kangaroos continue to be controversial in Canberra is because we haven't yet found a way of managing landscapes that treat wildlife with compassion and empathy, and that's what we need to do. And by continuing to purport this idea that killing solves problems is not going to resolve anything."

A spokesman from the ACT government said they are yet to decide if a cull will take place this year and that present procedure is in place to protect kangaroo young.

"The ACT government has always restricted its culls to the period between 1 March and 31 July. This is designed to minimise the chance of orphaning dependent joeys and young-at-foot."