Pelicans are large aquatic birds known for their distinctive bills and feeding behaviors. They exhibit unique adaptations that allow them to efficiently capture and consume prey from aquatic environments.
Specialized Anatomy for Foraging
The pelican’s most distinctive anatomical feature is its gular pouch, a large, elastic membrane extending from the lower jaw. This pouch, made of highly flexible skin, can expand significantly, allowing the bird to scoop up large volumes of water and fish. The lower mandible of the bill forms a framework supporting this pouch, which functions as a specialized net. Unlike many birds, pelicans possess a tiny tongue, which does not hinder the swallowing of large fish. The upper mandible often features a downcurved hook at its tip, aiding in securing slippery prey.
When engaging in a catch, the pelican can contract muscles around the pouch, pulling its flexible lower jawbones outward to create a wide, basket-like opening. Air sacs located beneath the skin, particularly on the breast, also contribute to the pelican’s buoyancy and help absorb the impact of water entry during hunting. This combination of a highly adaptable pouch, a specialized bill, and internal cushioning allows pelicans to forage effectively underwater.
Diverse Hunting Techniques
Pelicans employ varied hunting techniques depending on their species and habitat. The Brown Pelican, a coastal species, is known for its plunge-diving. These birds can spot fish from heights of up to 60 feet, tuck their wings, and dive headfirst into the water at steep angles, often between 60 and 90 degrees. Upon impact, the pelican opens its bill and expands its pouch to scoop up fish and a large volume of water. This maneuver is aided by reinforced skulls and necks, along with a slight body rotation upon entry, which helps prevent injury.
In contrast, American White Pelicans, often found in freshwater lakes and marshes, primarily use cooperative fishing strategies. They do not plunge-dive but swim on the surface, herding fish into shallow waters. Groups of these pelicans may form a line or a semi-circle, using their large wings and synchronized movements to drive fish toward the shore or into dense clusters. Once the fish are concentrated, each pelican dips its bill into the water to scoop up its prey. This collaborative approach allows for efficient capture of large numbers of fish with less individual effort.
The Swallowing Process
After scooping up fish and water, a pelican must drain excess water from its gular pouch before swallowing. This prevents the bird from ingesting large amounts of water, which would make flight or swimming difficult. The pelican achieves this by lifting its head and tilting its bill downward, allowing water to flow out through the sides of its slightly parted mandibles. The pouch muscles contract, expelling water while retaining the captured fish.
This draining process is swift and precise, ensuring that the pelican does not lose its meal. Once most of the water has been expelled, the pelican tosses its head back, allowing the fish to slide down its throat headfirst. This ensures smoother passage and helps prevent the prey from getting stuck.