A pig, a bear, and a fruit fly go into a bar. What drove them to drink—and what did they order?

Naturalist and author Sy Montgomery has an answer. She first noticed animals interacting with alcohol when her pet piglet, Christopher Hogworth, took an interest in a beer her husband was drinking.

"We thought, 'oh we wonder if he'd like the end of this, and he sure did. What is beer but liquid grain, right?" she said.

"I think he really liked the taste," she continued.

Christopher Hogworth, at a formidable 750 pounds, never got drunk. But it piqued Montgomery's curiosity. Soon, she, learned that plenty of other animals do.

Bohemian waxwing birds in Canada's Yukon Territory, for example, were found to fly out of formation last year after a bumper crop of mountain ash berries, which waxwings eat, became overgrown and began to ferment.

"So many of them were getting drunk on the berries that the town had to have a dry-out tank for these poor birds," Montgomery said. "You don't want to be flying drunk: that's the absolutely worst thing you could do."

These birds were not trying to get drunk on purpose. But other animals, like the mandrill baboob, actively seek out behavior-altering substances.

One researcher found that, when preparing for combat, male mandrils seek out the root of a particular plant two hours before looking for adversaries.

"He's waiting for this drug to take effect," Montgomery said. "It's just like courage in a bottle."

Sy Montgomery is a naturalistand the author of "The Soul Of An Octopus." To hear more from her interview, tune into the audio link above.