Kodi and I are seeing many mallards in wetlands on our daily walks. Mallards migrate south from breeding grounds from August to December, although some hang around all year in places with open water. Their peak flight is about now -- in October and November. Kodi gets a little frisky in the water when he sees them, but they just swim farther away and do not seem overly bothered by him.
Two years ago we were in Charlotte, Vermont for the Christmas holiday and rode the ferry across Lake Champlain from Charlotte to Essex, New York. A group of mallards were hanging around the harbor in Essex. These were likely year-round birds; their tameness probably a result of regular feeding by tourists and residents.
It was a chilly day, although the ducks didn't mind. I am always amazed that they can stand with their bare webbed-feet on frozen ground.
Mallards are the most widespread and common duck in the world. They are the ancestor of almost all domestic ducks (except the large Muscovy duck). The males are commonly called "green heads." The females are light brown, better for camouflage when sitting on a clutch of eggs. Mallards are dabbling ducks (as opposed to diving ducks such as mergansers, grebes, and sea ducks) -- they tip-up in shallow water (so you just see their rear end) to feed on aquatic plants and insects. Black ducks, teals, pintails, shovelors, and wood ducks are among some of the other dabblers.
North America supports nearly 10 million breeding mallards in the wild. Mallards do interbreed with domestic ducks and even some other species in the same genus, Anas. Biologists have long been concerned about "genetic swamping" of other ducks, especially the American black duck, by mallards interbreeding with them. So, sometimes you might see a smudge of green on a male black duck's head. Black ducks tend to be more wily and secretive than mallards, so biologists and hunters were concerned that mallard genes would make them tamer. I am not sure that has played out to date. Most of the black ducks that I see quickly take flight long before we get too close. Mallards, on the other hand, often look to see if someone is throwing bread crumbs their way. I don't feed ducks as it often creates a nuisance and makes them less wild.