Which of the following waterfowl have a smaller wing to body mass ratio?

Diving ducks typically exhibit a smaller wing to body mass ratio compared to the other groups listed. This characteristic is largely due to their adaptation to a life where they pursue food underwater, necessitating a body structure that allows for better buoyancy and propulsion within the water. As a result, they tend to have more robust bodies and larger mass relative to their wing size, which facilitates diving rather than extensive flight.

In contrast, dabbling ducks, geese, and swans, while also adapted for flight, possess different body and wing conformations. Dabbling ducks generally have a higher wing to body mass ratio, which supports their ability to take flight quickly from water surfaces. Geese, known for their migratory patterns, have significant wing size to enable sustained flight over long distances. Swans, being large birds, have longer wings proportional to their body size to support their heavy mass during flight, particularly given their powerful flapping and gliding abilities.

Overall, the smaller wing to body mass ratio of diving ducks is a reflection of their ecological niche, specialization for diving, and the consequent need for a body that is optimized for underwater foraging.