Animal rights campaigners said the man was approached by police officers near the Rose Cottage horse paddocks in Wanniassa on Wednesday night after blowing a whistle to disrupt shooting of eastern grey kangaroos in the area.

Trained marksmen and activists have spent recent nights at nature reserves around the ACT as the government seeks to shoot 2400 kangaroos and joeys by the end of the month. Shooting started at the end of April.

An ACT Policing spokesman confirmed rural patrol officers arrested a 70-year-old Macarthur man about 8.40pm on Wednesday in the Wanniassa Hills Nature Reserve area.

"The man was conveyed to the ACT Watch House and charged with obstruct/resist territory public official," the spokesman said.

"The man received bail and will face the ACT Magistrates Court."

The Territory and Municipal Services Directorate would not confirm shooting in the area this week was connected to the government's cull, citing safety concerns.

"Acts of vandalism this year include damage to temporary and permanent signage as well padlocks and fences," the spokeswoman said.

Last year, more than 1500 kangaroos were shot of a planned 1606. Another 514 joeys were killed in the shoot. In 2013, 1149 kangaroos and 355 joeys were killed.

No legal challenge was launched to stop the 2015-16 cull, as the government's Conservator of Flora and Fauna issued a two-year licence for shooting of 5000 kangaroos.

Previously, ACT Civil and Administrative Appeals Tribunal rulings have limited the number of animals shot.

Animal Liberation ACT spokeswoman Carolyn Drew said the arrest showed the territory government was repressing protests.

"He was outside a paddock that didn't have any trespass signs on it as far as we know so this is just another way for the government to try and shut us down and not allow any narrative other than their view of why kangaroos should be killed," she said.

Ms Drew said protesters had disrupted shooting activities five times so far in 2015, both north and south of Canberra.

Activists opposed to the shooting of kangaroos would continue nightly efforts to disrupt their shooting, Ms Drew said.

Shooting is taking place at nature reserves including Callum Brae on Mugga Lane; Crace, Goorooyarroo, Gungaderra and Mulanggari in Gungahlin; Kama and the Pinnacle near Hawker; Mount Painter near Cook; and Wanniassa Hills.

The sites are closed between 3pm and 7am each day, except Mount Painter, the Pinnacle and Wanniassa Hill, which are closed from 5pmto 7am.