Ducks are aquatic birds, and some species exhibit a remarkable behavior: diving completely beneath the surface. This deep dive allows them to access resources and escape threats.
Diving vs. Dabbling Ducks
Waterfowl are categorized into two main groups based on their feeding habits: diving ducks and dabbling ducks. Dabbling ducks typically feed by tipping their bodies forward, submerging only their heads and necks to reach food near the surface or in shallow water, with their tails often remaining visible above the waterline. In contrast, diving ducks fully submerge themselves underwater to forage in deeper environments.
Key Motivations for Diving
Ducks primarily dive underwater to forage for food beneath the surface. Diving ducks consume a diverse diet, including aquatic plants like seeds, roots, and tubers, as well as various aquatic invertebrates such as insects, mollusks, and crustaceans. Some species, like mergansers, also pursue small fish. The depth at which they forage varies, with some species diving into waters 10-65 feet deep, and certain long-tailed ducks capable of diving much deeper.
Diving also serves as a defense mechanism, allowing ducks to evade predators. When faced with threats such as aerial predators like eagles and hawks, or aquatic predators like large fish and some mammals, ducks can quickly submerge themselves. By diving, they disappear from sight, making it difficult for predators to track them. This ability to escape underwater is a significant survival strategy.
Physical Adaptations for Underwater Life
Diving ducks possess several specialized physical adaptations for underwater life. Their bodies are more streamlined and compact than dabbling ducks, reducing resistance as they move through water. Their legs are positioned farther back on their bodies, providing powerful propulsion for swimming and diving, though this makes them less agile on land. Large, webbed feet act like paddles, generating significant thrust underwater.
Specialized feathers also contribute to diving efficiency and buoyancy control. Their dense plumage traps air, which provides insulation and helps with buoyancy. Before diving, ducks can compress their feathers to squeeze out trapped air, reducing their buoyancy and making it easier to submerge. The layered structure of their feathers helps prevent water from reaching their skin even under pressure, allowing them to shake off water upon surfacing. Physiologically, diving ducks exhibit a “diving reflex” when submerged, reducing heart rate and redistributing blood flow to prioritize oxygen for the brain and sensory organs. This allows them to tolerate periods of low oxygen and remain underwater for typical durations of 10 to 30 seconds, and sometimes over a minute.
Additional Diving Behaviors
Beyond foraging and predator evasion, ducks may dive for other reasons. They engage in preening, using their bills to clean and arrange their feathers, and spreading oil from a specialized gland near their tail to maintain waterproofing. While much preening occurs on the surface, ducks can also perform some cleaning behaviors while partially submerged. Diving can also be part of social interactions, such as courtship displays or playful chases.