GAY OLD TIME - NOT: A school in Victoria has created controversy by banning the word gay from the classic Aussie song Kookaburra Sits In The Old Gum Tree.

A fat kookaburra is making slow progress on a weight loss programme at Sydney's Taronga Zoo.

A local Mosman resident found the over-fed Australian native bird being chased by dogs at Rawson Park on May 4.

It weighed 545g, 40 percent more than the typical kookaburra, and was unable to take flight.

"I've seen many kookaburras, but never before have I seen one so fat," Taronga Zoo wildlife hospital nurse Gemma Watkinson said.

Since then, the bird has been on a "strict" diet and exercise regime.

The female bird tipped the scales at 481g at a recent weigh-in - 20g short of its target.

It can't be released back into the wild unless it can shed those last grams, the zoo said.

Zoo staff are hopeful the bird will pass its next weigh-in, and can be returned to its Mosman stamping ground next week.

- AAP