Do you keep your vegetables on one shelf in your fridge, and eggs and meat on another?
A new study shows that humans aren’t the only species that organizes things like this – squirrels do it too.
Fox squirrels organize their stashes of nuts by variety, quality and possibly even preferences – evidence of a cognitive strategy called chunking.
Fox squirrels stockpile at least 3,000 to 10,000 nuts a year and, under certain conditions, separate each cache into ‘subfolders’, one for each type of nut
The study, conducted by researchers at the University of California, Berkeley, is the first to show evidence of squirrels arranging their finds using ‘chunking,’ a cognitive strategy in which humans and other animals organize spatial, linguistic, numeric or other information into smaller more manageable collections, such as subfolders on a computer.
Fox squirrels stockpile at least 3,000 to 10,000 nuts a year and, under certain conditions, separate each cache into ‘subfolders’, one for each type of nut.
‘This is the first demonstration of chunking in a scatter-hoarding animal, and also suggests that squirrels use flexible strategies to store food depending on how they acquire food,’ said study lead author Dr Mikel Delgado, a post-doctoral researcher who conducted the study along with UC Berkeley psychology professor Dr Lucia Jacobs.
Presumably, the researchers say, sophisticated caching techniques maximize the squirrels’ ability to remember where they’ve stored their most prized treats while at the same time hiding them from potential thieves.
‘Squirrels may use chunking the same way you put away your groceries,’ said Dr Jacobs, the study’s senior author.
‘You might put fruit on one shelf and vegetables on another.
‘Then, when you’re looking for an onion, you only have to look in one place, not every shelf in the kitchen.’
To conduct the study, the researchers tracked the caching patterns of squirrels over a two-year period.
The researchers tracked 45 male and female fox squirrels as the reddish gray rodents buried almonds, pecans, hazelnuts and walnuts in various wooded locations on the UC Berkeley campus.
The study also involved using a combination of locations and nut sequences on various groups of fox squirrels.
For example in one experiment, each of the squirrels were fed 16 nuts, one after another, under two separate conditions.
Some of the squirrels were fed at the same place where they had cached the previous nut fed to them, while others were fed at one central location, to which they would need to return if they wanted another nut.
The researchers gave some squirrels 16 nuts in rows of four, for example almonds followed by pecans, then followed by hazelnuts and then walnuts – while other squirrels received 16 nuts in random order.
Presumably, sophisticated caching techniques maximize the squirrels’ ability to remember where they’ve stored their most prized treats while at the same time hiding them from potential thieves. Pictured is an Eastern fox squirrel on the UC Berkeley campus
Using hand-held GPS navigators, the researchers tracked the squirrels from their starting location to their caching location, and then mapped the distribution of nut types and caching locations to detect patterns.
They found that the squirrels who foraged at a single location frequently organized their caches by nut species, returning to, for example, the almond area if that was the type of nut they were gathering, and keeping each category of nut that they buried separate.
By contrast, squirrels foraging in multiple locations deliberately avoided caching in areas where they had already buried nuts, rather than organizing nuts by type.
‘These observations suggest that when lacking the cognitive anchor of a central food source, fox squirrels utilize a different and perhaps simpler heuristic (problem-solving approach) to simply avoid the areas where they had previously cached,’ the study concludes.
In a study, researchers tracked 45 male and female fox squirrels as the reddish gray rodents buried almonds, pecans, hazelnuts and walnuts in various wooded locations on the UC Berkeley campus. Pictured is a squirrel dragging leaves and dirt over its nut stash