Although none have yet been announced, an Animal Liberation ACT spokeswoman said she anticipated culls in the capital, after a landcare group which had spent a decade trying to nurture and reclaim rare woodlands on Mount Majura said kangaroos were destroying its efforts.

Friends of Mount Majura said they had collected native grass seeds, tried to re-seed the reserve, only to have them eaten out by large numbers of roos.

More kangaroos have arrived since road work started on the Majura Parkway, which has driven feral animals up the mountain into sheltered woodlands on Canberra's northern outskirts.

Friends of Mount Majura co-ordinator Waltraud Pix said that since 2009 the group had been checking grazing impacts of kangaroos, rabbits and weather on the reserve's herbaceous ground layer.

"We fenced small grassland areas to exclude kangaroos and rabbits, kangaroos only, or none of the two herbivores and recorded the changes of the ground layer with repeat photography at fixed times of the year,'' she said.

''We were astonished to observe how the lawn-like grass layer recovered as a response to removing grazing pressure.''

With three years of repeat photographic records of the seasonal changes, and separate impacts of kangaroos and rabbits, the evidence is now conclusive.

Territory and Municipal services director of Parks and Conservation Daniel Iglesias said staff were counting kangaroos on reserves around Canberra and a decision on whether to cull some of the animals this year would be based on the numbers observed.

But he said the Friends' observations on the impact of kangaroos were backed by science.

''We're not saying there isn't a place for kangaroos, there is of course a place for kangaroos in the environment, but where we have a situation where there are too many, the body of evidence is growing that there is impact on the environment,'' he said.

But Animal Liberation ACT spokeswoman Carolyn Drew said there was never a need to cull kangaroos, because they regulated their own numbers, and more volunteers than last year would turn out to attempt to interrupt any shootings.