They saw an opportunity and they seized it, set it up, then scaled it.
Some enterprising chimpanzees at the Belfast Zoo in Northern Ireland's capital, propped a tree branch against the wall of their enclosure Saturday to make an improvised, yet sturdy, ladder.
"Don't escape, you bad little gorilla," a child chimed in as stunned zoo visitors filmed the breakout. (She was right about the absconding, if not the actual animal). Two chimpanzees manage to make it to the top of the wall as a third attempts to scramble up and join them. One perched above scurries away. The child repeats with more urgency, "Mom, it's escaping!"
Later, video shows a chimpanzee striding down an embankment and onto a roadway, leaving the wall of its enclosure behind it.
Watch chimps use branch to climb out of enclosure at Belfast Zoo (footage courtesy of Dean McFaul) pic.twitter.com/qrdQSZxSqt— BBC News NI (@BBCNewsNI) February 9, 2019
Alyn Cairns, a zoo manager, told the BBC that the escape was short-lived and the animals went back inside the enclosure themselves.
But the Belfast City Council, which operates the zoo, said in a statement released to media outlets that "the animal was quickly returned to the rest of the group by zookeepers."
A recent wind storm is thought to have knocked down the branch, setting the stage for the caper. Zookeepers were sure to remove the branch.
"We like things to be natural in their enclosure, to have trees in it, but we will review it," Cairns said. "We may have to remove the trees or make them a smaller level."
The city council said despite chimpanzees' natural curiosity, "this is a highly unusual event."
But it is the second animal getaway in as many months at the zoo. On January 27, police asked area residents to be on the lookout after one of four of the zoo's rare red pandas slipped loose. The animal, named Amber, was discovered a day later not far away. The zoo said a power failure in the electric fence around the animal's habitat was to blame, reports the BBC.
Regarding the great ape escape, the city council said the zoo is taking extra precautionary measures.
"Additional security checks are also being carried out at other enclosures following this incident, to ensure the health and safety of both animals and visitors."
Chimpanzees are natural builders adept at using tree branches to build their nightly nests for slumber, reports Natural Geographic.
But if constructing an ad-hoc ladder seems more advanced, consider this: chimpanzee and human DNA is about 99 percent the same.
Chimpanzees, alongside bonobos, are the closest living relative humans have, notes the American Museum of Natural History.