How do you get a bear to ride a bicycle? In addition to "very carefully," the answer is operant conditioning. A trainer rewards a particular behavior when performed by a subject, reinforcing the behavior in that subject. Thus do seals eventually balance beach balls, dogs roll over and frat boys run through halls in their underwear. But you've probably never seen the technique used on the world's tallest living land-dweller. I was visiting the Wildlife Conservation Society's Bronx Zoo on February 13 when I chanced upon mammal trainer Brandon Moore engaged in a conditioning session with a giraffe.

When the giraffe backs up in response to Moore's hand signal, Moore uses a handheld clicker as a bridge between the behavior—backing up—and the reward—a tasty piece of kale. The sound lets the animal know immediately that it did well and a reward is on the way. Moore next has the giraffe approach him and touch its nose to a blue-and-white ball on the end of a long stick, which gets the animal another piece of green. (Seemingly extraneous clicks are made off-camera by trainers working with other giraffes.) The overall goal is to teach the giraffes to take direction from zoo staffers.