The Blue-winged Teal (BWT) is a small, highly migratory species of dabbling duck found across North America. This bird possesses an omnivorous diet that changes significantly throughout the year, adapting to food availability and its physiological requirements. Its feeding habits are directly tied to its life cycle, which includes long-distance migration and reproductive periods. The Teal’s diet shifts between animal and plant matter to ensure it meets the differing nutritional needs of each season.
Primary Diet of Aquatic Invertebrates
The Blue-winged Teal’s animal diet consists mostly of aquatic invertebrates, which are a concentrated source of protein and essential minerals. These small prey items are particularly important for females during the reproductive season, providing the building blocks for egg production and the subsequent growth of their ducklings. Specific items consumed include aquatic insect larvae such as chironomids, midges, and mosquito larvae, which thrive in the shallow wetlands the teal frequents. Teals also consume small crustaceans, including copepods, cladocerans, and amphipods, abundant in temporary and seasonal wetlands. Mollusks, like small snails and bivalves, along with small amphibians such as tadpoles, round out the animal portion of the diet.
Essential Seeds and Vegetation
Plant matter constitutes a major part of the Blue-winged Teal’s diet, especially during periods when energy storage is prioritized over protein intake. This vegetation provides the bulk and high-energy carbohydrates necessary for general maintenance and migration. The teal consumes the seeds of numerous emergent marsh plants, including sedges, panic grass, smartweed, and wild millet. The birds also feed on the vegetative parts of aquatic plants, such as the leaves and stems of duckweed, pondweed, and muskgrass. In agricultural regions, the teal will opportunistically forage on waste grain, such as rice and milo, left behind in flooded fields after harvest.
Specialized Foraging Techniques
The Blue-winged Teal is classified as a dabbling duck, which describes its unique method of feeding without fully submerging its body. This technique involves skimming the water surface with its bill to filter out small invertebrates and seeds floating there. The duck also employs a head-dipping behavior, where it partially submerges its head and neck while swimming forward to grab items just below the water line. The teal rarely “up-ends,” a technique where other dabbling ducks tip their bodies vertically to reach deeper food. This preference for surface feeding dictates that the Blue-winged Teal primarily forages in extremely shallow water, often less than 8 to 12 inches deep.
Seasonal Dietary Shifts and Nutritional Needs
The ratio of animal to plant matter in the Blue-winged Teal’s diet fluctuates dramatically in response to its annual cycle. During the spring and summer breeding season, the diet shifts heavily toward protein, with invertebrates sometimes making up nearly 99% of the food consumed by laying females. This high-protein intake is necessary for the production of lipid-rich eggs and the rapid growth of the young. As the ducks move into the fall and winter, their nutritional focus changes from protein synthesis to energy storage for migration and survival. The diet shifts to rely predominantly on seeds and vegetative matter, which are rich in carbohydrates and fats.