Bird of the Season: Surf Scoters - Black Hills Audubon Society
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We saw [surf scoters] swallow entire clams. How, we wondered, could they manage to digest those shells? Checking one of our bird books we learned that while mussels and clams are their primary diet, they also eat small crabs, marine snails and worms and, along the Pacific coast, herring spawn. Along with all this protein and calcium they also consume aquatic vegetation. Since these ducks have no teeth they swallow all their shelled prey whole.
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This starts an amazing digestive process in which the powerful muscles of their gizzards pulverize the whole clams, including the shells. Those shell fragments are then small enough to pass through the digestive tract, helping to grind the food as they move along. With the benefit of those shell pieces, Surf Scoters, unlike most other avian species, don’t need to swallow rocks to improve their digestion.
