This waterfowl is agile in flight and good at swimming, often seen feeding on the surface. What is it?

The correct choice describes a group of ducks known as "puddle ducks," which are also called dabbling ducks. These ducks are characterized by their unique feeding behavior; they feed by tipping their bodies forward in the water while keeping their tails up, allowing them to reach underwater vegetation and insects without fully diving. This surface feeding technique highlights their agility both in flight and while swimming.

Puddle ducks are typically found in shallow wetlands, ponds, and marshes, where they can easily access food. Their adaptations for this type of feeding and their preference for these habitats make them commonly observed on the water's surface. In contrast, other types of ducks, such as diving ducks—like the scaup or canvasback—tend to dive deeper to feed. Teal ducks are a subset of puddle ducks and while they also fit the description, the term "puddle duck" encompasses a wider range of species that share similar behavioral traits. Therefore, the classification of puddle ducks as agile flyers and strong swimmers that often forage at the surface aligns perfectly with the described characteristics in the question.