It was interesting to watch this pair of Shoveler Duck this week feeding in the shallow area of one of the lakes in the local parkland. They were working together by spinning around in the same spot with their long beaks submerged in order to stir up the silt at the bottom. Just like an auger. I read that they filter food through the sides of their beaks such as plankton, crustaceans, insects and seeds and squeezed the water out with their tongues.
I did also observe another male Shoveler in a deeper part of the lake diving for about an average of 6 seconds at a time. After about each five dives it would shake the water form its wings. It didn't realise they were diving ducks as well.