Eagles and turtles, and any number of carnivorous predators that can catch one will eat ducks. Many of the predators, including raccoons and possums will raid duck nests and eat the eggs. My uncle saw a large mouth bass swallow a duckling during one of his fishing trips. Don't forget that people find ducks to be good eats, too.
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Most any carnivore or omnivore that is able to catch or find a duck could eat it. Ducks might be captured and eaten as adults, or they might be eaten as young while in or out of the nest. Duck eggs, like most all bird eggs, are also vulnerable to predators.
Ducks live in most parts of the world, they typically next at ground level, and their ducklings both walk and swim before they can fly, which means they have a very wide variety of natural predators.
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Among the more common predators that prey on ducks are humans, fox, coyote, mink & weasels, wild cats, bobcats, pumas, hawks, falcons, owls, eagles, ocean birds such as heron, large fish like pike or sharks, and reptiles like snakes or alligators and crocodiles.
Bears, foxes, dogs, cats, hawks, falcons, eagles, big snakes, Fichte's, weasel's, pretty much any predatory animal.
Snapping turtles, too. Ducks are really never really safe wherever they are.
The duck will get sick
A duck that eats fish is known as a "dabbling duck." These ducks primarily feed on plant matter and small invertebrates but may also consume fish occasionally. An example of a dabbling duck that eats fish is the Northern Pintail.
raccon
Yes the puma could choke on the duck's bill or the duck could give the puma mercury poisoning after it eats the duck.
Ensure the mallard duck gets good nutrition.
duck and fish&& stuff !!
duck weed
Hawks, coyotes, wolves, etc.
It surprisingly enough eats Frogs.
In the story Peter and the Wolf, the wolf eats the duck.
The name of a duck that eats fish is the merganser. Mergansers are diving ducks that have long, serrated bills that help them catch and eat fish.
some humans do. Also alligators.