The overwhelming pain of grief can drive anyone into out-of-the-ordinary behaviour, even a 62kg orangutan.
Karta, a 27-year-old Sumatran orangutan at Adelaide Zoo, has cut a lonely figure since her mate, Pusung, 31, died from a respiratory infection last month.
Zookeepers believe the grief of losing her partner, known as the "gentle giant" of the zoo, led to Karta's ingenious escape yesterday from her enclosure.
The drama began about 11am, when Karta used a stick to short-circuit electric wires, which are used to protect vegetation around the bottom of the orangutan enclosure, zoo spokeswoman Emily Rice told The Australian.
"She climbed over those disabled hot wires, built up a mound of leaf litter and then used a branch to climb out of the exhibit and on to the surrounding wall of the exhibit."
It was the first time an orangutan at the zoo had ever left the enclosure, and it forced the evacuation and closure of the zoo for the rest of the day.
Staff last night were still trying to coax the clever orangutan inside her night den, although she had earlier voluntarily returned to her enclosure.
"It is unusual," Ms Rice said. "Certainly, we have never had an orangutan out before, but they are such an intelligent species. While orangutans have been known to make tools and so forth in the past, it is unusual for them to try and get out like that."
Once outside the enclosure, Karta spent the next 30 minutes trying to find her way back in.
Witness Ryan Johnston, 11, told of the orangutan's great escape.
"It was amazing how she did it, because she actually got a branch, pulled it over the electric fence and then got over," he said.
Ms Rice said Karta was not aggressive and did not pose an immediate threat to the public.
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