Final answer:
Ducks are the aquatic birds with three-toed webbed feet that migrate frequently.
Step-by-step explanation:
The group of birds that are aquatic, have three-toed feet with the toes linked together by webbing, and migrate quite frequently are ducks. Ducks are categorized as waterfowl, birds that live on the water, which also includes geese, swans, and pelicans. Ducks have webbed feet that are excellent for swimming and floating, allowing them to navigate aquatic environments efficiently. These birds also engage in migration, a common phenomenon among birds, to reach climates with sufficient food supplies during different seasons.