It made me smile for a few reasons. I'm fascinated by corvid behavior, and this was the first time I'd seen a crow doing this — using height, gravity, and a hard surface to open a nut.
It also helped me solve a mystery. A few days before this, we had found a large walnut in the front yard (on a patch of cement). There aren't any walnut trees growing adjacent to our house, so we wondered where the nut had come from. When I saw the crow dropping the walnut on the street, I realized what had probably happened.
And, seeing a crow with a walnut (and then finding many walnut shells in the area) also provided some circumstantial evidence for another puzzle. You might recall that I've been watching some White-tailed Kites come to an evening roost, and that in the 1960s a large kite roost was reported in Cotati (see post from 5 October 2015). Those kites were roosting in a walnut orchard, so I had been wondering about whether there used to be a walnut orchard near this house.
Of course, I'm left with another piece of the puzzle — exactly where are the crows getting the walnuts, and how far is that site from our house? We'll have to start scanning for walnut trees in the neighborhood.
Perhaps both the crows and the kites have an interest in walnuts, but for different reasons?