Flying high at Low Tide

I got this photo sometime last week while walking along the seawall. What I noticed right away was how low the tide was under the bridge - to the point where the bridge footings themselves were so exposed you could see that the dirt underneath them had been washed away (or dredged?)

What I did not notice until I got home and looked at my pictures on the computer was the little bird flying by in the bottom of the photo. This was not the first bird I saw that day - a bunch of crows were flying right at me it seemed, one after another. As it turns out, they were picking up mussels that were exposed from the low tide, and were flying over to the street where they could break the shells. It was unusual because as they were gaining altitude to reach street level, they were basically approaching me head on. I thought I had wandered too close to a nest until I saw what they were doing with the mussels.