The Australian arm of the animal rights group PETA wants The Hills Council to stop killing red foxes at Bidjigal Reserve.
They have organised an online petition calling on people to write to mayor Michelle Byrne about the council's baiting program, which has been going for 10 years. They even provide a sample letter.
"The only humane form of euthanasia is lethal injection - all other methods of slaughter, including shooting, poisoning, trapping and hunting with dogs, cause fear, pain and long agonising deaths," campaign co-ordinator Claire Fryer said.
But Steve Parker, a ranger with Cumberland Livestock Health and Pest Authority, said native wildlife would "be left to fend for themselves against fox predation" if the council stopped its current pest management practices.
Foxoff poison baits containing 1080, a pesticide form of sodium monofluoroacetate, are buried in three local reserves — Bidjigal, Eric Mobbs and Excelsior — twice a year.
"Foxes generally die of cardiac arrest or heart failure," Mr Parker said.
"It's important to understand nobody likes to kill things; this program is primarily about the conservation and protection of native species."
A council spokesman said the RSPCA deemed the use of 1080 as "conditionally humane and lawful", as there is no alternative, effective control method available.
Australia's largest owl, the endangered powerful owl, is among the species breeding in Bidjigal.
You will also find echidnas, sugar gliders, wrens, thornbills, kookaburras, crimson rosellas, sulphur-crested cockatoos and rainbow lorikeets.
There have been reported sightings of swamp wallabies and brush turkeys.
Have you had problems with foxes? How do you deal with them?