posted May 10, 2009 07:25 AM         

The elaborate plot by 27-year-old Karta got her to within metres of the public, and resulted in the closure of the zoo on one of its busiest days of the year.

The alarm was raised by a member of the public about 11am.

Zoo curator Peter Whitehead said Karta had twisted a stick into hot wires that encircled her enclosure, short circuiting the wires and allowing her to enter a vegetated area near the concrete and glass fence that separated her from the public.

She then piled up sticks, grass and plant roots and used them to climb onto the fence.

”You're talking about an animal that's highly intelligent, Mr Whitehead said.

”We've had issues with her before in normal day to day operations where she tries to outsmart the keepers.

”So in this case she's decided to make a ladder and try to get out of her exhibit.”

Mr Whitehead said Karta was on the fence for about half an hour before climbing back down into the exhibit.

Veterinary staff had been on standby with tranquiliser guns but these had not been necessary.

”I think when she actually got out and realised where she was ... she's realised she shouldn't be there so then she's actually hung onto the wall and dropped back into the exhibit,” Mr Whitehead said.

He said although she was not an aggressive animal and was always “quite a few metres” from the public, the zoo had been evacuated as a safety precaution.

A spokeswoman for the zoo later said it was unlikely the gates would reopen today.

Mr Whitehead said there would be a “thorough review” of the morning's events, and it was likely some of the vegetation in the enclosure would be removed.

Following the escape attempt Karta was being enticed into her night enclosure and away from the public viewing area.

This task was taking longer than anticipated and was the cause of the longer than expected closure of the zoo gates.peMr Whitehead said orangutans were not generally an aggressive animal and Karta was often used to interact with the public in behind-the-scene zoo tours, although there was always mesh between her and the public.

”She's an ingenious animal,” he said