Riding horseback in the rural outskirts of Woodland, CA years ago, I noticed the crows there had developed a rather clever plan for extracting the inner contents of walnuts from hard surrounding shells. Crows would perch themselves in branches of walnut trees that lined country roads–a rather commonplace arrangement in Yolo County. As a vehicle approached, hopefully a truck or tractor, the crows would fling down a barrage of walnuts a few seconds before it passed by underneath them. Occasionally, the walnuts would land in-line with the vehicle’s tires, that crushed them on impact. The crows then enjoyed the nutty feast left behind, for minimal exertion on their part.
Walking back to my car the other day, I noticed crows enacting another maneuver for nut extraction. As you might be able to make out in the (low-quality, phone-captured) video below, a crow can be seen lodging a nut in the crevice separating slabs of pavement in a cement street. With the nut pinned in place, the crow could pierce it with his bill and pull out the nutty goodness.
Contrary to what was once believed, primates are not the only creatures in the animal kingdom cunning enough to use tools.