Why did the cat cross the canal swing-bridge?

It is a question I can't answer, but I was amused when it popped into my line of sight this afternoon. I like its determined motion and the somewhat quizzical look in its eye, wondering what I was doing. I wondered what it was doing crossing a bridge in the middle of the countryside, but I suppose that it was going home to one of the nearby houses. It needed to run to take advantage of a gap between cars, lorries and tractors.

I was standing beside Parkend swing-bridge over the Gloucester to Sharpness canal trying to catch images of swallows. They were swooping around and over the water, and then under the bridge to feed their young which I could hear twittering in the nests under the feet of the cat. Whenever the bridge swung open to let boats pass the swallows kept on arriving with food and happily adapted their flightpaths to squeeze into the narrow spaces under the  metalwork supporting the road surface.

I did catch a few pictures of swallows but none that really caught my attention. The shadows beneath the bridge don't allow for easy photography.