If you get a good egg laying breed (Khaki Campbells, Welsh Harlequins, Runners) they will outlay your chickens. The eggs are jumbo sized and are excellent for eating and baking.
They are more naturally disease resistant than chickens and are extremely cold hardy. On days that my chickens refuse to leave the coop (-20 degree temps) my ducks were outside swimming in their water bowl. When it gets cold, my chickens almost completely stop laying eggs. My ducks keep right on laying.
They are so much fun to see waddling around the yard. My Mallard also flies around the yard.
Yes ducks are a messier fowl than a chicken, but then they are heavier layers than chickens and require water to eat with. As ducks like to put their food in the water bowl. They dig in their nesting areas so you may have to do a treasure hunt collecting eggs. I have French Rouen ducks and I love them. THey are even great neck nusslers if ya get them use to being picked up. Mine are allowed to free range during the day so they head right out the pasture to one of the ponds and come back up in the eveing to the duck shed. They have been laying daily since November. We get any where from 3-7 eggs a day. I have 6 hens and 4 drakes.
This photowas taken last Sept the boys have all their color now
Are ducks better behaved in a garden than chickens are? Are they as inclined to dig?
Mine don't bother anything in the garden or flower beds. They hang out near the pond. They also don't "dust" themselves like chickens so you don't have all the holes. They do poke around with their bills but not nearly the damage that chickens can create.
It seems mine dig in the mud, wherever they find it. I keep them out of the garden once it is planted in the spring, I imagine they would like to snarffle around in the mud after I water. And I'm sure they would enjoy tasty young lettuce and spinach plants!