re they are often vagrants and less often residents. A handful are endemic to such far-flung islands. A brown duck in a fast-flowing stream Female mallard in Cornwall, England Some duck species, mainly those breeding in the temperate and Arctic Northern Hemisphere, are migratory; those in the tropics are generally not. Some ducks, particularly in Australia where rainfall is erratic, are nomadic, seeking out the temporary lakes and pools that form after localised heavy rain. Behaviour Feeding Pecten along the bill Mallard duckling preening Family of ducks preening Ducks eat food sources such as grasses, aquatic plants, fish, insects, small amphibians, worms, and small molluscs. Dabbling ducks feed on the surface of water or on land, or as deep as they can reach by up-ending without completely submerging. Along the edge of the bill, there is a comb-like structure called a pecten. This strains the water squirting from the side of the bill and traps any food. The pecten is also used to preen feathers and to hold slippery food items. Diving ducks and sea ducks forage deep underwater. To be able to submerge more easily, the diving ducks are heavier than dabbling ducks, and therefore have more difficulty taking off to fly. A few specialized species such as the mergansers are adapted to catch and swallow large fish. The others have the characteristic wide flat bill adapted to dredging-type jobs such as pulling up waterweed, pulling worms and small molluscs out of mud, searching for insect larvae, and bulk jobs such as dredging out, holding, turning head first, and swallowing a squirming frog. To avoid injury when digging into sediment it has no cere, but the nostrils come out through hard horn. The Guardian published an article advising that ducks should not be fed with bread because it damages the health of the ducks and pollutes waterways. Breeding A Muscovy duckling Ducks generally only have one partner at a time, although the partnership usually only lasts one year. Larger species and the more sedentary species (like fast-river specialists) tend to have pair-bonds that last numerous years. Most duck species breed on
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