“Whoosh!” exclaims my friend Frank, as he thrusts his cupped hands upward, nearly knocking over his drink on the table between us. We are sitting in my backyard in Leiden, the Netherlands. Frank is demonstrating how, once or twice each day, a peregrine falcon swoops upward past his hospital office window with a freshly killed pigeon in its talons, headed for its lair underneath the giant illuminated logo at the top of the building. A few seconds later plucked feathers come drifting down.