Female chimpanzee
© NELSON ALMEIDA, AFPA female chimpanzee holds her baby at the Great Apes Project (GAP), a sanctuary for apes in Sorocaba, some 100km west of Sao Paulo, Brazil.
Most of us would wish to escape from captivity and a group of abstract thinking chimpanzees temporarily managed this feat by building a makeshift ladder to escape from Belfast Zoo.

In February 2019, a group of enterprising chimpanzees managed to get out of their enclosure at Belfast Zoo (Northern Ireland) by propping a tree branch against the wall to enable their improvised escape. Video footage provided by NPR (see below) shows two chimpanzees making it it to the top of the wall with one of the chimpanzees scurrying away. In all, five chimpanzees left their enclosure.

The escaped chimpanzee was later seen striding down an embankment and onto a roadway. However, later all of the chimpanzees returned home, apparently not caring much for human habitats. Speaking with The Guardian, Zookeeper Alyn Cairns states that the trees in the enclosure had been weakened by the storms (such as the recent Storm Eric), providing structures for the chimps to break and use as ladders to escape.

He adds, about the chimps returning home: "They're intelligent primates and know they're not supposed to be out of their enclosure, so got back in themselves."

Chimpanzees are adept at using tools and primatologist Frans de Waal told Business Insider that chimpanzees can do almost everything that was once considered a distinctively human trait.

Belfast Zoological Gardens is located in the northeastern slope of Cavehill, Belfast. The zoo hosts over 1000 captive animals and receives more than 300,000 not-so-captive animals in the form of fee paying visitors each year. The zoo is owned by by Belfast City Council and it costs around $2.5 million per year to run.

Belfast City Council said what happened at the facility on Saturday was "a highly unusual event".