While enjoying a leisurely lunch last weekend at the top of Forbes Bench in Mt. Tamalpais State Park, my friend and I encountered very curious crow behavior. The updrafts/winds were allowing the crows to cruise around effortlessly.
As we sat there, looking up, one pair of crows would fly in tandem and occasionally, the larger crow, would roll 180 degrees upside down and cruise directly beneath the smaller crow. This upside down behavior occurred roughly every 10-15 seconds and lasted for about 10 minutes. Was this a mating ritual? Training for attacks? Play? We weren't sure. We did notice several pairs/threesome/groups of crows all over the hills, however, doing similar antics.
While we were marveling in this behavior, we soon spotted a solo crow exhibiting very interesting flight patterns...to the point where it seemed it was enjoying itself. It would pirouette, twist, roll over, dive bomb, stall, etc. Like a little stunt bird, or one who suddenly realizes, "hey, i can fly" and takes advantage of Bernoulli's law, it was having the time of it's life...letting out a "caw caw" every 5 seconds or so. It took a break after 5 minutes of this and perched upon a nearby tree.
Unfortunately, no one else was around to ask if these behaviours were ordinary. During a web search, I came up with someone who had witnessed similar behavior.
I wrote a letter to the Chronicle's Outdoors beat writer, Tom Sienstra. If he responds, I'll post his response.