The escape began promptly after morning tea.
The father went first. He headed into the green murk, likely for the first time in his life. He used reeds for balance while slowly floating across the moat that had enclosed him for seven years. His two sons quickly followed, leaping from a rope over the small expanse of water. Within minutes, the trio were on the outside. They were free.
They tipped over wheelie bins. They sat on picnic benches and swung from roof gutterings. They appeared calm as they peered through glass windows at the animals now locked in small enclosures around the park.
The call came through: The gibbons were loose. About 200 humans were shut in safe houses. The message was simple: Get the apes back.
Christchurch's Orana Wildlife Park has a containment manual for each of the 70 species in its care. There are risk profiles of each animal and how best to recapture them if they happen to escape from their respective enclosures. They could be frightened or aggressive. They could lash out.
The emergency plan was implemented as soon as the three Siamang gibbons were seen on the wrong side of their monkey island last Saturday: Get visitors in lockdown. Lure the animals back into a safe enclosure. Recapture. Have a tranquiliser gun on standby. Along with big cats, baboons and chimpanzees, gibbons are high on the shoot-to-kill list. So if humans are at risk, or it's probable the apes might escape from the park, replace that tranquiliser gun with a real one.
But the Siamang family did not terrorise any visitors. Instead, park spokesman Nathan Hawke said, they seemed to be relatively content.
"They behaved very calmly but you never know how they are going to react in a certain situation."
Seeing an animal escapade seems to trigger an excitement in humans; they almost long for the critters to continue their journey - to jump the fence and live out their lives in the wild as nature intended.
"There is a real desire in today's modern concrete jungle to be in touch with nature and see those species out and about," says renowned animal behaviour expert Mark Vette. "But obviously that is not suitable."
EVERY ANIMAL escape and attack in New Zealand is reported to the Environmental Protection Agency. There is a long list of animal escapes from enclosures since records began in 2004-2005.
In 2006, a red panda escaped Hamilton Zoo. It was run over by a car on the outside. In 2007, a male capuchin monkey escaped Franklin Zoo in Auckland and was on the run for nine days before being found under a shed.
Ring-tailed lemurs, spider monkeys, antelopes, otters and cotton top tamarins have all thwarted the supposedly rigorous containment procedures for New Zealand's captive animals.
In 2004-2005, only three incidents of attack or escape were reported. In the 2012 financial year there were 22.
For all zoo keepers the worst scenario is one of those escapes turning into a serious attack on a person. So why do we have so many of them?
"We are dealing with living, clever critters," says national manager of the Zoo and Aquarium Association Stephanie Jervis.
"We can put everything into place and work thoroughly through every eventuality but things can happen."
Even with the Ministry of Primary Industries (MPI) regularly monitoring animal containment practices, the unforeseen can occur.
Earthquakes, snowstorms and human error can all contribute to an animal escape, says Jervis, who heads the representative group that most zoos in the country belong to.
In the case of the Orana gibbons, however, she says the unforeseen was more straightforward.
"We didn't know that Siamangs are able to swim."
It was a similar situation in 2010 when three of Orana's normally water-averse cheetahs escaped their enclosure, also by swimming a moat, and roamed the public area for 30 minutes before being recaptured.
In some cases, all the procedures, regulations and ever-modernising facilities count for nought. Life, it seems, will find a way.
However, Safe director Hans Kriek says the effort to give animals "modern" enclosures has created zoos that look better for people but are not necessarily better for animals. Kriek, a former zoo worker turned animal welfare advocate, says animals like gibbons used to be kept in square metal cages.
"It gave the animals a three-dimensional environment. But humans don't like seeing animals behind heavy looking bars."
So the idea of islands came in, which, Kriek says, "looks a hell of a lot better". But when you looked at the amount of space in such enclosures there was less room to move than the old cages. Often there was more ability for them to escape.
While Kriek is against the enclosure of animals in general, he says the move to modernised environments is actually a factor in why so many animals - particularly apes - seem to get loose. And when that happens, he says, the biggest risk is to the animal themselves.
"It is well recorded that when they escape they often end up dead. [Zoos] can't afford to take the risk."
The most well-known case of that occurring was in 1967 when two tigers, Napoleon and Josephine, escaped from their Wellington Zoo enclosure after a keeper failed to properly close their door.
Just after 1am on March 19, Paul Russell saw Napoleon padding down a Newtown street.
"I thought I was seeing things," he told the Dominion newspaper the next day.
The two tigers were shot by police.
The MPI says New Zealand's containment standards are international best practice and informed by international standards.
"It would be unwise to state that containment breaches are completely preventable, as mistakes can happen," a ministry spokesperson says. "However, MPI's guidelines and requirements are designed to ensure that breaches happen rarely and that there are plans in place to mitigate any breaches with no harm to either the public or any animals."
Wellington Zoo general operations manager Mauritz Dasson says it tends to go above those minimum standards.
"On a normal good day, with all things equal, a lion will be content and happy but then comes something- a bizarre explosion or a fight breaks out in the group or a storm and that is when they show how agile and how amazingly keen they will be to get out."
But some smaller zoos around the country are known to be more relaxed with their interpretation of the rules, he says. Animals will always do something that surprises you.
"We are not arrogant enough to say we are smarter than them and say they won't get out. We will look after them but if they want to show how smart they are your jaw will hang open," Dasson says.
As for Oscar and the other Siamangs, the whole family is under house arrest and unable to get back to their island until the moat has been deepened and widened. That, says Hawke, will ensure they can never escape never again. After all, gibbons don't like water and they certainly can't swim that far. Right?
