The number of eastern grey kangaroos in the territory will be reduced by almost 2,500 during a controversial annual cull, the ACT Government has announced.

Parks and Conservation director Daniel Iglesias said 2,466 kangaroos would be culled across Canberra's nature parks between April 30 until August 1.

That number is up almost 1,000 animals on last year's target of 1,600 kangaroos.

Mr Iglesias said after successive years of culling some areas like Mulligans Flat now had sustainable kangaroo numbers, but this year culling would also take place in Gungaderra Nature Reserve, resulting in a higher target number.

"There isn't a need to cull in those areas at all this year, so what we've done is we've incorporated some priority nature reserves which we haven't culled in before," he said.

Mr Iglesias said the majority of the extra quota was accounted for by culling at Gungaderra Nature Reserve.

"Culling of overabundant kangaroos is currently the most humane method of population control available to the ACT Government as a responsible land manager," he said.

"However we are continuing to explore alternative, non-lethal options to reduce the population of kangaroos and protect the biodiversity of Canberra's nature reserves."

In July the Government will begin a two-year trial into the effectiveness of contraceptive darts to control kangaroo numbers across Canberra.

The drug, GonaCon, has been used overseas to stop female deer, bison and boar from producing young, but the ACT trial on about 200 kangaroos will be an Australian first.

Legal action held up 2014 roo cull

The annual culls have been marred by various protests and legal challenges over the past six years, with animal activists arguing there was no scientific evidence to prove reducing kangaroo numbers helped the environment.

The Government has consistently argued that heavy grazing by kangaroos threatened the survival of some grassland sites and species.

But last year Animal Liberation ACT took legal action to try to stop the kangaroo culls and also opposed fertility control measures.

As a result, 1,519 animals were shot during 2014's winter at eight reserves, just short of the target of 1,600 after court action slowed the start of the annual cull.

Animal Liberation ACT spokeswoman Carolyn Drew said the group had not yet decided if it would launch a legal challenge to this year's cull.

Ms Drew said in some ways a legal challenge was a dead road.

"It does make you question as to whether that's the path to go, the legal challenge, because the law nearly always upholds the status quo," she said.

Greens Minister Shane Rattenbury said an annual cull was the most responsible way to manage native woodlands and grasslands for the benefit of all species.

"I don't think anybody involved likes the fact that we need to undertake a cull each year, I certainly don't like it, but as a responsible land manager we have a job to do," he said.

"Unfortunately our ecology is imbalanced as a result of a range of factors, predominantly driven by human population growth."

This year Callum Brae Nature Reserve, Crace Nature Reserve, Goorooyarroo Nature Reserve, Gungaderra Nature Reserve, Kama Nature Reserve, Mount Painter Nature Reserve, Mulanggari Nature Reserve, Wanniassa Hills Nature Reserve and the Pinnacle Nature Reserve will be closed during the evening between Thursday April 30 and Friday August 1.