A goat who lives among kangaroos in southern Adelaide has become the focus of a development fight by some locals who are keen to preserve remaining open space.

Government agency Renewal SA wants to sell just over 42 hectares of land next to Commercial Road at Seaford Meadows, saying it is one of the largest remaining residential sites available in the southern Adelaide region.

Locals said Gary the goat was a local identity and lived there among a mob of kangaroos.

When sale signs went up on the land recently, southern resident Christine Keen took to Facebook to comment.

"Love to see the roos and goat as we drive past on a regular basis, noticed the land for sale signs ... my daughter's first question: 'Mum, what will happen to the kangaroos and the goat? Where will they go?'"she wrote.

A Facebook page created as a tribute to Gary has more than 4,700 likes and thousands of people have signed a petition opposing development of the pocket of land.

Locals are using Gary the Goat to highlight their anti-housing development push. ( 891 ABC Adelaide: Spence Denny )

Local woman Jan, who checked out Gary with her binoculars this morning, told 891 ABC Adelaide he was a local tourist attraction worth preserving because of his interactions with the dozens of Seaford roos.

"He's just part of the family, he follows them around all day, and they do play together," she said.

"Our relatives from England came over and they hadn't seen wild kangaroos so we took them over here. It's different from seeing them in a park. They're huge."

The kangaroos and Gary like to play, a local woman said. ( Facebook: Leave Gary the Goat Alone )

There is a theory that Gary escaped from a hiring firm which used to provide goats in the area if people wanted their yards cleared of excess vegetation.

One resident, Leonie, claimed she saw the goat living in a kangaroo pouch back when she was a child, but another southern resident Babs said: "This is not a laughing matter, extend the [local] reserve".

Expressions of interest for the development site are due to close in the middle of next month.