Jays actively plan for their future food needs, findings of new research claim.
Experiments have shown that they store more of the foods that they know will be unavailable to them on future foraging trips, according to the research published in the journal Biology Letters.
Jays cache acorns throughout autumn, to be unearthed later in winter, with each individual bird capable of burying thousands of acorns. Scientists analysed this caching behaviour to test whether or not Jays actually think into the future.
Previous studies by Professor Nicola Clayton on scrub jays, distantly related to Eurasian Jays, had shown that when they were offered so much of one food that they became sick of it, they would still cache it. She interpreted this to mean that the birds knew they would want that food in the future.
“The difficulty though, is that we don’t know what they know, we only know what they’re doing,” said Lucy Cheke, who works with Prof Clayton and carried out the more recent experiment. The scrub jays might have simply worked out which foods stored well and which did not.
To eliminate this possibility, the researchers put four adult Jays through a four-day test.
On day one, the Jays were presented with two differently coloured boxes in which to hide food. They could gather this from a mixed pile of peanuts and raisins.
The following day, the scientists fed the birds only with raisins, then offered them just one of their boxes. On day three, the birds were given a pile of peanuts before being presented with the other box.
“The day after that, they came to cache again,” said Ms Cheke. “Just before they cache, they’re fed a big pile of peanuts, so when they come to cache, they’re sick of peanuts.
Instead of ignoring the peanuts and only stashing the raisins, the birds appeared to plan ahead, storing raisins in the tray they were offered after their peanut binge and peanuts in the one they were offered after being fed raisins.
“Imagine a child is packing two lunch boxes – one for this afternoon and one for tomorrow,” Ms Cheke said. “If this afternoon they know they’ll get to eat loads of cake before their lunch, they’ll know only to pack sandwiches in that lunch box.”
Other researchers based in the same Cambridge laboratory have found examples of what they think is “mental time travel” in wild birds.
Some bird species in Costa Rica follow army ant swarms through the forest, indulging in an insect feeding frenzy as flying insects flee the ant raid.
Researcher Corina Logan has observed birds checking ant bivouacs – the temporary nest structures that the ants construct at the end of their raid. She and her colleagues proposed, in a paper in the journal Behavioural Ecology, that the birds might return to the nest sites the following day, in order to follow the next ant raid.
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