At about 10:40,I stopped at the Emeryville Crescent to take a look at Espie. She was on the NW corner, facing in. After about 10 minutes she started getting restless and at 10:55 she took off toward Aquatic Park. I watched her stoop and chase what looked like a redtail (something bigger than she is, but Aquatic Park is a half-mile away so confirmed ID is not possible). She stooped a couple more times, then rose and circled for 5 minutes, going higher. I lost sight of her so I left. As I was driving down the Frontage Road, she was coming back, flying just off shore along the crescent, empty-taloned. She headed toward her building. At noon when I returned, I circled the building and didn’t see her in any of the obvious places.