The Weber Report

“At the Institute for Marine Mammal Studies in
Mississippi, Kelly the dolphin has built up quite a reputation. All the
dolphins at the institute are trained to hold onto any litter that
falls into their pools until they see a trainer, when they can trade
the litter for fish. In this way, the dolphins help to keep their pools
clean.

Kelly has taken this task one step further. When people drop paper
into the water she hides it under a rock at the bottom of the pool. The
next time a trainer passes, she goes down to the rock and tears off a
piece of paper to give to the trainer. After a fish reward, she goes
back down, tears off another piece of paper, gets another fish, and so
on. This behaviour is interesting because it shows that Kelly has a
sense of the future and delays gratification. She has realised that a
big piece of paper gets the same reward as a small piece and so
delivers only small pieces to keep the extra food coming. She has, in
effect, trained the humans.

Her cunning has not stopped there. One day, when a gull flew into
her pool, she grabbed it, waited for the trainers and then gave it to
them. It was a large bird and so the trainers gave her lots of fish.
This seemed to give Kelly a new idea. The next time she was fed,
instead of eating the last fish, she took it to the bottom of the pool
and hid it under the rock where she had been hiding the paper. When no
trainers were present, she brought the fish to the surface and used it
to lure the gulls, which she would catch to get even more fish. After
mastering this lucrative strategy, she taught her calf, who taught
other calves, and so gull-baiting has become a hot game among the
dolphins.”