Animal advocates say a planned two year kangaroo cull is unnecessary as natural population levels have already reduced by 56 per cent and shooting could see eastern greys disappear from Canberra's landscape.
Responding to reports released as ACT government officials announced the opening of the cull last week, Regional Friends of Wildlife said on Wednesday that shooting kangaroos to reduce overgrazing in nature reserves was unethical and could damage the territory's tourism industry.
The controversial kangaroo cull is set to begin at the end of the month, but it is still unclear if it will face a renewed legal challenge in 2015. The government has secured a two-year cull license and trained shooters will kill more than 2400 animals at eight nature reserves and associated land.
Regional Friends of Wildlife spokesman Steve Garlick said the continuing annual cull efforts meant most Canberra residents, visitors and tourists would be unable to see kangaroos, except in national parks and around Queanbeyan.
Professor Garlick also serves as president of the Animal Justice Party, which won a seat in the New South Wales Parliament's upper house on Friday.
Releasing a report and map prepared by field ecologist Ray Mjadwesch in 2013, Professor Garlick said eastern grey kangaroos were already gone from 26.6 per cent of the territory because of urban land use, and a further 29.9 per cent of the animals were under pressure.
Only 15.2 per cent had natural densities in intact habitat. The remaining 28.3 per cent is unsuitable habitat.
Professor Garlick said the government's reports falsely showed over abundant numbers of kangaroos, while the animals could be willing and able to co-exist with humans.
Mr Mjadwesch's report had formed part of expert evidence in the unsuccessful 2013 ACT Civil and Administrative Tribunal challenge against the cull. The challenge, led by the Australian Society for Kangaroos, saw the total number of culled animals reduced.
A similar challenge last year, led by Animal Liberation ACT, was also unsuccessful.
"This work suggests that eastern grey kangaroos may have experienced an overall decline across at least 56.5 per cent of the ACT, including total extinction from over a quarter of their former range," Professor Garlick said.
Last week ACT Parks and Conservation director Daniel Iglesias released a range of information to explain why the cull was required, including a report summarising eight research papers released since 2010 that show the environmental threat from high and damaging kangaroo densities.
They show overgrazing by kangaroos can damage ecosystems, threaten species, including four types of woodland birds and the endangered grassland earless dragon, striped legless lizard and Perunga grasshopper.
One of the papers is under review.
The government also used the announcement to explain how it calculates the number of animals killed in the cull effort. Its preferred density is one kangaroo per hectare in grassland, with between 50 and 90 per cent of grassland numbers in woodland and 10 per cent in forests.
Officials said reserves with 100 hectares each of forest, open woodland and grassland could sustain 200 kangaroos. An audit in 2013 found that of carcasses inspected after the cull, all of the kangaroos had been killed with a single shot.
"ACT government ecologists determine the maximum number of kangaroos that can inhabit an area before the ecosystem can no longer support the population to set what is called the "carrying capacity"," a government-released guide said.
"Kangaroo populations are estimated using scientifically based methodology that is used across all Australian jurisdictions."
Culling will take place at Mugga Lane; Crace, Goorooyarroo, Gungaderra and Mulanggari; Kama and the Pinnacle; Mount Painter; and Wanniassa Hills.
The shooting sites will be closed between 3pm and 7am each day, except Mount Painter, the Pinnacle and Wanniassa Hill, which will close from 5pm till 7am.
An unsuccessful legal challenge in 2015 would give the government two years of of culling without further delay.