The Genius of Birds

by Jennifer Ackerman

WESTERN SCRUB JAYS—those masters of social trickery—remember not only where they stashed their caches (and who was watching) but also what they stashed there and when. This is important because the scrub jay squirrels away not only nuts and seeds but fruit, insects, and worms, foods that perish at different rates. Cached insects can spoil in days if the temperatures are high enough, while nuts and seeds can last for months. A series of creative experiments by Nicola Clayton and her team at Cambridge University showed that the birds retrieve the more perishable food before it rots, leaving the nonperishables, such as nuts and seeds, until later. The jays use their experience of how quickly food degrades to guide their choice in recovering their caches. Remembering that perishable food items may need to be retrieved sooner requires recalling cache locations, cache contents, and the time of caching. This ability to remember the what, where, and when of specific past events is thought to be akin to human episodic memory, the remarkable capacity to remember specific personal experiences. Like us, the birds seem to be using events that happened in the past (what they buried when) to figure out what to do now or in the future (dig up or save until later).