'It took quite a while for him to get his legs under him. He kept tipping over on his left side, going in circles to the left one side was working and one wasn't.''

Without this help, Mr Miller thought his chance of survival were remote. ''I don't think so, it was a really hard labour … it would have been very difficult for him to survive in the wild.''

With no detectable heartbeat for three days, zoo staff were especially worried about brain damage, but Mr Miller said that fear had evaporated as the calf demonstrated ''amazing recuperative powers'' and was reaching developmental milestones right on time.

''I'd say he's going to be 100 per cent,'' he said.

''Today's milestones says he's strong enough to negotiate uneven ground.''

The zoo's next big challenge is to convince people to stop calling him Mr Shuffles, the name staff gave him in those first perilous days he was upright.

Instead, they'd prefer to give him a Thai name to remind people of the origin of his parents. They have asked the public to vote on a list of seven Thai names on the zoo's website.

http://www.taronga.org.au/