For a long-term, committed conservationist Lyn Goldsworthy's love for cats inexplicable – until a crimson rosella lands in a low branch of a maple tree above Katchi, her creamy-coated Birman.
Katchi's no slouch, his name is Japanese for sharp energy, yet rosellas and fairy wrens in her Gordon backyard know he'll never catch them because his long leash keeps him grounded.
Ms Goldsworthy once led an international campaign to ban mining in Antarctica, has campaigned to stop bottom trawling in the high seas and is a contractor for the World Wide Fund For Nature on marine protected areas.
In her other role, as executive director of the Frank Fenner Foundation, which aims to integrate humans and the environment equally, Ms Goldsworthy lives with compromises. Her partial disability means the family needs two cars, but she can compensate for their environmental impact with solar panels at home, composting and a host of other steps.
Blue tongue lizards and birds fill her garden because she is prepared to watch over Katchi when he's outside, and her 4½-month-old kitten Teagha, who is being introduced to a leash.
The sooty-faced, microchipped cats explore beneath two bird feeders and trickling water fountain down a slope from a native garden.
"I strongly believe in protecting the natives of the area and always have but I also love cats.
"My Mum had a terminal illness and for the past two months of her life when she was confined to her bed they bought her massive comfort. I think cats bring a measure of comfort to a lot of people, and I think you can work out with whom you can co-exist."
Ultimately Ms Goldsworthy plans to build cages, or fenced runs for her cats. Leashes can be tedious to manage.
"People say cats kill lots of animals. Yes, so do the dogs," Ms Goldsworthy said. "At the very least people should put their cats in at night to give birds a chance of waking up in the morning."
RSPCA Australia says contained cats are less likely to be hit by cars, lost, or injured in a cat fight. They should have plenty of horizontal and vertical climbing space and toys to keep them amused.