Think chimps aren’t so smart? Maybe you should think again. (Tiziana Fabi/Agence France Presse via Getty Images)

It wasn’t careless zookeepers who were responsible for the escape of seven chimpanzees from their enclosure at the zoo in Kansas City, Missouri, last week.

It was clever chimpanzees.

“Chimps are so smart,” zoo director Randy Wisthoff said.

One of them, he said, either found or broke off a five- or six-foot log or branch, leaned it against a wall and climbed to the top. Then, six of that chimp’s friends followed.

The zoo activated its emergency procedures, which included gathering visitors into secure areas. People who were visiting the zoo were never in danger, Wisthoff said.

It took about an hour for zookeepers to herd the animals, in groups of two or three, back into their home.

They used fruit and vegetables, the chimps’ usual food, to get six of the chimps to return. To persuade the last one to come back, zookeepers brought out a bag of malted-milk balls.

“That was the clincher,” Wisthoff said.

— Kansas City Star