I made this image on Alcatraz Island. This pair of Western Gulls, part of a huge colony, were engaged in a courtship ritual that involved touching bills, striking poses, and making considerable noise. It is never easy composing an image based on the behavior of people, animals or birds. We can only study that behavior, noting its physical structure and directional flow, and hope that it happens again. In this case, I found these gulls courting on a ledge with the Golden Gate Bridge in the background. I simply watched and waited over a ten-minute period, until a boat full of tourists appeared to supply my middle ground, and one bird raised its bill skyward, vertically echoing the thrust of the tower of the Golden Gate Bridge. I was able to make an image that offers three horizontal thrusts – the birds on the ledge, the boat and its wake, and the bridge with its background hills. I played three vertical thrusts against them – the upright bill of the gull, the rising column of plants at left, and the upward thrust of the tower of the Golden Gate Bridge. There is also an implied diagonal thrust as well – the clusters of plants at left point towards the tower and are echoed by the rounded shape of the mountain at right.