The Western scrub jay is a remarkable bird. The bright blue jay is famed, like many corvids, for his smarts. The jay buries his food, storing it for later, and not only recalls where he’s put it, he guards against other wily jays by moving his cache when he sees another bird around. But what this tells us about the bird’s intelligence is a topic stirring up scientific debate.
On one side there are those who believe that this proves scrub jay’s have “theory of mind.” Theory of mind is a concept from human psychology. Put simply, it’s the ability to understand and intuit that other individuals have their own distinct minds and thoughts. It’s realizing, for example, that another bird watching you cache a snack might intend to steal it, and that hiding that snack in a new location could trick the visitor and protect your treat.
Theory of mind may sound basic but it’s actually a demanding and complex social ability that even humans struggle with. A human infant may not develop theory of mind until around four years of age. As a result, claiming jays have this ability has ruffled feathers among biologists and psychologists alike. Leading some to suggest this may just be an example of social learning, where birds find from trial and error that not moving your grub leads to unfortunate consequences.
This week, University of Groningen theoretical biologists published a study putting forward a new explanation of the bird’s behavior. Perhaps the jays are simply stressed out, and operate on the basic rule: keep food far from others. Later, the birds have cached and re-cached so much that the confused jays keep caching even when left alone, still stressed by the entire ordeal.
To test their hypothesis they created computer modeled “virtual birds” that behaved according to their stress-theory. They found that real and virtual jays behaved in the same way, and interpreted this as evidence supporting their explanation. Lead author Elske Van der Vaart was especially intrigued by what the birds did when left alone, caching and re-caching even after an hour or two had passed.
"That's really mysterious," says Van der Vaart. She observes that their theory is the first to suggest memory may contribute to the situation, as behavioral evidence hints that birds cache and re-cache so often that they don't quite remember where they've stored their snacks. The additional stress results in even more caching.
It’s still too soon to say whether the study debunks the bird’s brainy reputation, however.
“A model can never prove that something is as simple as it looks,” Van der Vaart says. Instead, she hopes the model will help biologists pinpoint which variables need to be studied to assess scrub jay smarts. Van der Vaart herself was drawn to the research because she is fascinated by clever corvids, though she believes it’s important to temper excitement about animal intelligence with careful science.
For more on amazing corvid behaviors, and the brainy theories explaining them, don't miss Alisa Opar's "Problem Solvers: Crows and Rooks Use Tools to Retrieve Food" and "Crows Don't Forget a Human Face." Or test your own wits with Michele Wilson Berger's quiz on the Western Scrub Jay's cousin, the Florida Scrub Jay.