Most of the ten or a dozen shovellers which had been overwintering on the West park lake have already departed for wherever they go in the breeding season. This pair have stuck around, at least for the moment.
I thought they had been heading for their preferred feeding area, to swim around in a tight circle with their beaks just under the water, filtering out the particles of whatever it is they eat. They reached the spot, but then put on a burst of speed, heading off in a completely different direction.