They will be confronted by protesters under the umbrella of the “radical action collective”, who Animal Liberation says have gathered in Canberra to disrupt the shoot.

The government will fight back, saying it will issue trespass notices to anyone found inside the closed reserves, with fines of up to $7000.

ACT Animal Liberation spokeswoman Carolyn Drew said it was a “David and Goliath battle”, and like looking for a needle in a haystack to work out where the shooters were on any given night. They shot without lights and used rangers at other nature reserves as a decoy, she said.

Parks and Conservation director Daniel Iglesias compared the opponents to climate change deniers.

“What we have is a situation not unlike the climate change deniers, where we have clear scientific evidence that suggests that a course of action should be taken and for whatever reason there’s a small group of people that just refuse to accept it. We’re talking about ideology with this group," he said. "As a land manager we have to act not on ideology but on what the best science is telling us.”

The tribunal categorically rejected every argument made by the animal welfare groups, he said.

The ACT Civil and Administrative Tribunal rejected Animal Liberation ACT’s appeal, satisfied the government had a “solid scientific basis" for the cull. It accepted the government’s contention that shooting the kangaroos was necessary to protect other threatened species that rely on the grasslands.

The three-person tribunal, headed by Graeme Lunney, rejected evidence from the animal groups that kangaroo communities were stressed by the break-up of family groups during the cull, a suggestion it said attributed a human emotion to the kangaroos. It said psychological damage was not a likely consequence of the cull.

It said translocation and fertility control were not yet viable alternatives to culling by firearms.

It also accepted evidence from a government witness that a number of still-dependent “young at foot” kangaroos would die as a result of the cull, but said while that was an undesirable outcome, it did not make the cull undesirable or unacceptable.

When shooters find “pouch young” – baby kangaroos young enough that they are still in the pouch – they are killed with a blow to the head, a fate met by 355 pouch young last year. Mr Iglesias said the cull was timed when young at foot (joeys still feeding from their mothers but no longer in the pouch) were rare.

Animal activists listened in silence to Mr Lunney reading the judgment until he said the tribunal was satisfied the cull proponents had a high awareness of safeguarding animal welfare, a comment met with sounds of disbelief.

Marcus Fillinger, who is in talks with the government about a fertility control trial and was a witness for the animal groups, emerged angry at what he said was "an indictment on the democracy I fight for in the military".

"This is basically the fox looking after the hen house and the ACT government marking its own homework," he said. "A bunch of kangaroos will die tonight because of this garbage."

Ms Drew said the decision was not unexpected.

"It’s basically the government evaluating itself, so we are not going to get very far with that road," she said.

The eight reserves will be closed in the evening and overnight from Monday until July 31 for the shoot. They are the Callum Brae off Mugga Lane, Goorooyarroo and adjacent land in Gungahlin, Jerrabomberra Grassland West, Kama near Hawker, Mount Painter near Cook, Mulanggari in Gungahlin, Mulligans Flat in Gungahlin, and the Pinnacle and adjacent land near Hawker.

Most of the reserves will be closed from 3pm until 7am each day. Two sites, Mount Painter and the Pinnacle, will close from 5pm each day and reopen at 7am.

Mr Iglesias said the appeal had delayed the start of the cull to the point that shooters might not reach the quota.