I started by noticing this cloud of birds swirling around, then I saw that one of them was MUCH larger than the rest. Then it swung around into the light so I could see the white head and tail markings. Meanwhile the crows were yelling and dive-bombing, and the eagle appeared long-suffering. Then it disappeared. Go figure.
I had heard that there was a pair of eagles in the neighborhood, and thought I'd seen one several times in the past year. This was the first time I could make an absolutely positive ID, though.
Wild life; cool.