Sydney (dpa) - A homesick cat walked 3,000 kilometers from far northern Australia to the other end of the continent to be re-united with her sibling, according to news report Tuesday.

That is the barely credible story from Sheree Gale, the owner of transcontinental tabby Jessie, who took 15 months to make the great trek from a farm near Darwin back to a homestead near Adelaide.

"I've heard too many stories like this not to believe Jessie's owners," Sydney veterinarian Peter Higgins said Tuesday.

"Cats and dogs don't have the cognitive ability that we have but if you think about it logically they instinctively know how to get back to where they came from. It's what they do in the wild."

Gale had two cats, Jessie and Jack, when she moved to Darwin in2010. Jack missed the flight because he was off wandering.

Gale was in touch with the family who rented her house and learned that Jack had returned and taken up residence.

"In May 2011 they told us that Jessie had rocked up. They sent us photographs and it was her. It was definitely Jessie," Gale told national broadcaster ABC.

She agrees that it is difficult to believe a 10-year-old cat would make that 3,000-kilometre journey.

"I know it seems totally ridiculous," she said. "But when you think she's an old farm cat who is tough as nails who has never been to a vet in her life and has walked for several kilometers a day."

Gale reckons it is unlikely that a farm cat like Jessie, timid and unused to vehicles, hitched a ride on a truck or on the train.

She also said that timing was important.

"Mother Nature was on her side because it was the year of the big wet season, which was closely followed by the mouse plague and the grasshopper plague and so there was food and water all the way down. Another year and I don't think she would have made it," she said.

Gale said she would not be separating Jessie and Jack again.

"No, when she's gone to all that trouble to get down there she can live out her days and stay with her brother and thankfully the family that are living in the house have been generous enough to feed her and her brother and its worked out very well in the end."