Mallards (Anas platyrhynchos) preening.
Feather maintenance is of course vitally important to birds. One of the things they have to worry about is feather lice, which, without regular bathing and preening, could become a problem. Interestingly, feather lice species have evolved over time to associate only with “their” species of birds. There is an analogy here with the species of lice associated only with humans; since we lost our luxurious fur pelts, our lice have diversified to specific parts of our bodies, and what was once a single species is now three.
Ducks in particular especially need to maintain their “waterproofing.” They do so by daily maintenance, smoothing out the barbs of their feathers, and applying preen oil from their uropygial glands with their bills.While Mallards are our most common and recognizable duck*, found on both fresh and salt water, as well as various admixtures of the two, other species are also found locally. Here’s a male Gadwall (Anas strepera) preening up a storm. Both of these species are regulars in the shelter of the artificial bays created by the piers of Brooklyn Bridge Park.
*Mallards are also the largest duck species in the region, barring the escaped domesticated ducks that often cluster on ponds and lakes, some of which look like Hulk Mallards. And fun genetic trivia: ducks are quite the cross-breeders, with crosses between Mallard and American Black duck, as well as others, often making appearances. Ducks turn the old hard and fast definition of “species” somewhat loosey-goosey.