Those are both articles about humans. A mammal.
People who work with ducks do not refer to this as a disease of ducks.
Humans are not migratory water fowl.
The other foie gras article by J Kenji Lopez-Alt gives a nice summary of why this is mostly not an issue for ducks. But its a summary. For a deep dive I’ll recommend Caro’s book again.
You see, migration depends upon gorging: the rapid intake and metabolism of large quantities of food in order to store enough energy to fly south for the winter. So, while during the warm summer months a duck may be content paddling around eating weeds, bugs, and the occasional minnow, when the weather starts getting colder, it begins to eat in earnest, stuffing itself more frequently, and with larger prey. Unlike in humans, where excess fat builds up mostly in large deposits just under the skin, with migratory birds, this excess fat builds up both under the skin and in the liver.
The fattened condition of the birds liver is quite unlike fatty liver disease in other animals, as the animals adapted to store mass amounts of fat in their livers. And to burn off that fat during migration. And do it over and over again. Every year. This isn’t something that a human or a cat is capable of.
