Mergansers are primarily piscivorous, meaning their diet consists mostly of fish. They also consume other aquatic animals such as insects, crustaceans, and amphibians. The specific diet can vary depending on the species and their habitat. The amount a merganser eats can vary based on factors like age, size, and availability of food. On average, an adult merganser can consume between 10 to 20 percent of its body weight in fish per day. For example, a Common Merganser, which weighs around 2 to 3 p