Many times they have their wings clipped during their first few years. Therefore, when they get older, they haven't learned how to fly. - There may be more to that answer, but that's the most I know. Our ducks and geese try to fly, but they don't get more then a few feet off the ground if they start from a hill or something.

These birds are an exception to the general characteristic feature of the birds-lacking air space. All birds that could fly have streamlined body structure with enough air sacks in their wings and space in the bodies to facilitate flight. But domesticated birds have less streamlined shape, almost no air sack in wings and lesser space. Also, they are more fleshy that adds more weight.

"because they are wings are not long enough" huh?

Both. They are too heavy and they lost the need to fly. On deomestication they no longer needed to forage for their food. They got used to overfeeding and put on weight. The need to roost on high tree branches vanished as they were well protected by their owners. Evolutionary process took care of the rest.

domesticated ducks, geese and turkeys for that matter have been bred and developed to have larger breasts, since that is where the majority of any birds meat is located. that heavy breast makes it impossible for the birds to maintain sustained flight.

It was a matter of breeding them for a purpose. The purpose was meat. It also didn't hurt that this makes them easier to keep penned on a farm. All domestic ducks except the muscovy are descended from the mallard, which can fly. The first link below has a lot of duck info, the second is pictures of the many many kinds of ducks that currently exist, all coming from the mallard, pictured below, once upon a time. http://www.feathersite.com/Poultry/Ducks/BRKDucks.html http://www.thegoosesmother.com/id92.html This one has some more info, very good place to buy a duck. (not an easy pet, though) http://www.metzerfarms.com/

While it's true that many cannot fly, that's not true of all. There are some domestic ducks that can fly very well. We've had some that flew around the ranch. But often, if you feed them well, they will just be too fat to get very high off the ground. The domestic geese are all too heavy to be good fliers. However I have seen some white Chinese geese get off the ground with a little elevated sloped ground though they didn't stay up in the air for very long. And I'm sorry I've run out of points for you:-(

Probably both. The varieties have been developed that way by humans. 1) "Go to any almost any park with a pond and you’ll find abandoned domestic ducks and geese. Most people probably don’t think about how the birds got there or why, and most also don’t know the difference between a wild duck or goose (which has feathers long enough for flight, and muscles designed for quick take-offs) and a domesticated one (which has been breed to be slow and flightless). However, there is a big difference between an animal that is born with all the instincts it needs to live its life independently of humans, and a domesticated animal that depends on humans for food and shelter." Source and further information: http://www.ibrrc.org/pdfs/Abandoned-ducks-geese.pdf 2) "Most domestic ducks cannot fly (the exceptions are; Muscovy's and Bantam's) and therefore cannot escape predators." Source and further information: http://www.lameduckrescue.com/Basic%20Care%20New.htm 3) "Ducks and geese are domestic animals. They have been bred to depend entirely upon our care. They can live anywhere from 8-15 years, sometimes even longer when properly protected in safe pens and maintained on healthy diets. When abandoned, many do not survive their first winter. Predators like owls, coyotes, dogs, raccoons and foxes, make quick work of these non-flying, defenseless birds. Many of them even succumb to acts of cruelty by humans. In addition, domestic waterfowl can not fly over land obstacles and often stumble and suffer serious hip, leg and foot injuries--breaks and dislocations." "When domestic ducks and geese breed with their wild counterparts, their offspring are usually flightless and unable to migrate as well. " Source and further information: http://www.majesticwaterfowl.org/