I put out peanuts for the scrub jays that nest nearby. It’s a daily amusement as the squirrels and jays compete for the food, with the occasional crow flying in to terrorize them both. A behavior I’ve noticed with the jays is that they will land, eyeball the peanut hoard, then pick one up, drop it, pick up another one, drop it, pick up a third, etc. until finally flying off with one.
So what is it they are doing here? Weighing the nuts, or just getting one that comfortably fits in the beak?
Hard to say, without taking actual data. My guess is that they are evaluating which is the best nut, whether by weight or some other factor. But at the end, they may not take the absolute “best” nut if they decide they are all more or less equal. They are just checking them all out.
Have you ever watched humans picking out fruit and veg from a supermarket loose display?
Maybe they are tasting it. No one likes biting into a bad peanut.
Probably not. Birds have a fairly limited sense of taste compared to mammals.
Like Alton Brown says about lemons, “you want one that’s heavy for its size”. Maybe that works for peanuts too.
GaryM
What I find intriguing is that when I put out food on the lawn, the first visitors are usually a couple of pigeons, followed by some starlings (sometimes a lot of starlings) and then some smaller birds, mostly sparrows. Now the pigeons will hop about eating what they can, but if they spot a sparrow, they will drop what they have to chase the sparrow off; then a starling will grab that and the pigeon will try to get it back.
There is plenty of food so if they all just ate what they can, they would all be full without all the aggro.
These are in the shell.
If that’s the case, it makes it more probable that they might be evaluating the weight. Peanuts in the shell might vary quite a bit in the size and number of nuts they contain.
You have the chance to do a real scientific study here! Weigh the nuts and number them in magic marker (or maybe mark them with different colored dots). Keep track of which nuts each jay picks up vs which ones it flies off with.
Mom tells the story of the raven at Hurricane Ridge that was faced with two graham crackers. He wanted them both but could not figure out how to pick up one without putting down the other. He did eventually manage to stack them crosswise and get both into his beak so he could fly off and eat in peace (or feed the kids).
I always buy poblano peppers that are light for their size. Those would have smaller inedible cores, and they’re sold by weight…
At least one study about this exact question suggested it was the weight. They might also be evaluating the hollowness of the shell by shaking it in their beaks and listening for a rattle.
Saves me from having to do a bunch of siencey stuff, which would just make me nuts.
Because, if that were to happen, the birds would be carrying you away.
But only if he’s heavy enough.
Hah!
I a year or so ago noticed our Blue Jays evaluating the peanuts we put out, and ran across the same study.
My friend has a similar situation occurring. She puts her nuts out for the jays, and she’s noticed/studied the behavior you’re describing. In her case, the nuts are placed on the wooden hand-rail along her outdoor deck. She watches them as they pick them up and drop them to the ground… off the deck and into the grass. They’ll then fly off with one nut in their beak, then they’ll return a little later to get the ones they had dropped on the ground. We hypothesize that the bird feels more protected down there.
African or European?
Wait. They drop the nuts off of the deck rail into the grass but for the one they fly off with, then return to pick through the ones in the grass? I’d guess they are just making the remainder less visible to their competitors while they are away.
There is at least one published research paper on it. (I did not keep a link.) In that case the jays were picking the heaviest peanut.