I know, I know, it looks so much like that’s what’s happening. The mouse is clearly interested; the crows walks the direction the mouse exited to, drops food, and leaves. But rather than sharing, this is simply a coincidental intersection of two animals trying to claim what they can.
First, a little bit of background information: In animal behavior, food sharing is defined as the transfer of a defendable food item from one individual to another, or the joint use of a monopolized item.1 Obviously these definitions are both broad and somewhat subjective. Because of this, you’ll see a range in how different papers describe how common this behavior is. Some might say it occurs frequently, while others say it is rare depending on if they’re including tolerated theft, food transfers during courtship, etc. Among corvids, evidence of food sharing has been suggested in ravens, rooks, scrub-jays and northwestern crows, but it’s been most formally studied in jackdaws.
Studies on jackdaws show that donor initiated sharing is more common than in primates (though more rare than recipient initiated sharing), sharing decreases as the birds get older, and that patterns of food sharing support both the altruism hypothesis (tit for tat) and the harassment hypothesis (take this and leave me alone!). A key thing among all these studies is that food sharing is taking place within social groups, not with strangers and not with other species.
Given the rarity and circumstances with which this behavior has been observed, even within corvid social groups, it is exceedingly unlikely that this crow is so generously sharing with a mouse. So how else could we explain it?
The crucial moment of truth comes at the 0:58s mark. Crows, like many other corvids, hide food for later consumption. If you’ve ever shared enough food with a crow that it constituted multiple morsels, you might have noticed this behavior. The crow will walk or fly to a location not generally too far away and tuck the food into a tree branch, under the soil, into your gutters, etc. Then, like clockwork, they will use some nearby debris to cover it. In the most adorable, “Damn why don’t I have my camera!?,” moments, I’ve seen them pick pansies to cover and hide their treats. At the 0:58sec mark you can see the crow pick up some sidewalk detritus and do exactly this. That’s not a signal of sharing, that’s caching loud and clear.
Some of you might be wondering why, given how smart crows are, it did such a poor job, considering the mouse was so clearly watching and ready to lift it as soon as the crow walked away. Crows are smart, and very good at some tasks, but as I’ve said before, the ability of an animal to excel at a cognitive task requires that that task in some way relates to their natural history. American crows are not good at, or perhaps even capable of, making hook tools because, unlike New Caledonian crows, there was no available food niche which selected this behavior. Likewise, American crows aren’t very cache protective because they don’t really need to be. There is so much food in the urban ecosystem that most crow caches will go uncollected anyway. On the other hand, the corvids that rely more on their caches are quite sensitive to onlookers. As for why it picked that particular spot to begin with, that was probably the closest cache location, and since the crow probably couldn’t see the mouse, there wasn’t any reason not to cache there.
One of the more elaborate explanations I’ve read falls decidedly in the opposite direction, however. The idea is that instead of sharing, the crow is actually baiting the mouse and the sprinkling of detritus on top was meant to slow the mouse down and facilitate the kill. While there are some birds, such as green herons, that do use bait to catch prey, this is not a consistent feature of crows’ hunting repertoire. That said, you can find the occasional video of crows using bait much like the herons. We can also rule out this explanation because 1) a leaf on top of a piece of bread will slow the mouse down for approximately 1/100 of a second and 2) the crow very clearly wandered away from, and lacked the focus on the food that would be required to actually catch the mouse.
So consider the food sharing crow video officially debunked. And don’t worry, there are still plenty of videos out there that are as exactly pure and wonderful as they seem. I’m not coming for your golden retriever.
- De Kort, S.R., Emery, N.J, and Clayton, N.S. (2005). Food sharing in jackdaws Corvus monedula: what, why and with whom? Animal Behaviour 72: 297-304. (scroll down to see PDF of paper)