Greater Flamingos and Nile Crocodiles in iSimangaliso Wetland Park at St. Lucia. Flamingos are filter-feeders with beaks which separate mud and silt from their food. They resemble whales and oysters more than they do most birds in this respect. Other avian filter feeders include some penguins and auks. The filter of the Greater Flamingo traps crustaceans, mollusks, and insects an inch or so long. We did not notice the crocodiles until we were back on our boat and enlarged our photos.