Have you ever put something where you were sure you could find it, and then forget where you put it?
What if you had to recover thousands of items that you had hidden several months ago in thousands of different locations?
Bet you couldn't do it. Unless, of course, you're a Clark's nutcracker. This amazing little bird, a member of the famously clever corvid family, collects 30,000 or so tiny pine nuts each fall, and then hides them in about 5,000 different locations over an area of about 15 square miles.
Then in the winter, when snow blankets its natural habitat in the western United States, the nutcracker returns to collect its cache with astounding precision.
"It's an amazing feat," said Brett Gibson, an animal behaviorist and assistant professor of psychology at the University of New Hampshire.
For several years now Gibson has been trying to figure out exactly how the nutcracker pulls off its magic every year. He's not alone. Other scientists have been working in the same field, and while they have a fairly good idea of how the nutcracker finds all those caches, it's still somewhat of a mystery.
Most research is done inside buildings, because studying these smart birds in their natural setting is very difficult. A bird doesn't always go where you think it's going to go, and it's pretty hard for humans to follow a bird because birds can fly, and we can't. So most of what we know about the nutcracker comes from the laboratory, which the birds seem to adjust to quickly.
One thing is clear. These birds have a phenomenal memory. That partly justifies some of the research, because there are still many unanswered questions about human memory, and the more we learn about memory in general the better the chance of understanding and dealing with our own memory problems.
But forget about that. For now, concentrate on the nutcracker.
The nutcracker is closely related to ravens and crows -- widely considered to be the smartest of birds -- and jays and magpies, my personal favorite. All have good memories, and ravens and magpies can count, or at least recognize groups of different sizes up to seven. But when it comes to feats of memory, the Clark's nutcracker tops the list.
Gibson thinks the nutcracker is able to produce a "cognitive map" that allows it to return to thousands of sites. He began studying nutcrackers as a graduate student at the University of Nebraska, where he tried to figure out how nutcrackers use landmarks to guide them back to their food.
His research, as well as that of others, suggests that nutcrackers are clever enough to determine distances and directions to various landmarks. One study showed that if a cache is buried midway between two landmarks, the nutcracker will return to the midpoint even if the landmarks are moved farther apart.
"That tells us they are flexible in how they use landmark information," Gibson said.
While at Nebraska, Gibson taught some pigeons -- not nearly as clever as nutcrackers -- how to use a computer to earn lunch. He was trying to solve what's called the Traveling Salesman Problem, or how to go to several destinations in the most efficient manner.
"Lets say I have 10 places to go to on a Saturday morning," he said. "What's the most efficient way to get there? It turns out that there's a large number of routes with 10 destinations. I don't know the exact number, but it's on the order of a million."
Gibson trained the pigeons to sit in front of a computer monitor and peck a series of 10 dots. They were rewarded with a snack if they did it efficiently. If they jumped all over the place, no snack.
"It only gets food if it connects all 10 dots efficiently," he said.
The pigeons were pretty good at it, he adds, so now he's gearing up to repeat the experiment in New Hampshire with nutcrackers. He expects them to be much better at it than the pigeons.
That would be strong evidence that nutcrackers do, indeed, create a "cognitive map" of their environment. That's important for reasons other than just retrieving their caches.
"If you take an inefficient route in the natural environment, you increase the exposure to predators, you waste energy, you spend time traveling that could be used in other activities, like reproduction," Gibson said.
His findings might have some practical applications for scientists who are studying human memory, but he admits that's not what drives him.
"Personally, I'm just intrigued by these birds," he said. "I think they're really neat."