The Arctic presents a formidable environment, characterized by extreme cold and dramatic seasonal shifts in daylight and food availability. Birds inhabiting this region have developed remarkable adaptations to survive these harsh conditions. Understanding their dietary needs and foraging behaviors offers insight into how these species persist in one of the planet’s most challenging ecosystems.
Primary Food Categories
Arctic birds primarily rely on a diverse array of marine and terrestrial food sources. Many seabirds, such as the Arctic Tern, predominantly consume fish, including small, schooling species like capelin, sandlances, herring, cod, and smelt. Arctic Terns also supplement their diet with marine invertebrates such as amphipods, crabs, and krill. Ivory Gulls feed on fish and invertebrates near ice floes, while Glaucous Gulls are opportunistic, consuming fish, mollusks, and crustaceans.
Common Eiders, for example, are diving ducks that primarily eat mollusks, particularly mussels and other bivalves, and crustaceans like crabs. They possess a muscular gizzard capable of crushing the shells of their prey. Krill, small shrimp-like crustaceans, support various birds.
Terrestrial food sources become available during the warmer months. In summer, species like the Rock Ptarmigan and some gulls consume insects, seeds, and berries. Ivory Gulls may add lemmings and other small mammals to their diet in summer and also scavenge carrion, including remains from polar bear kills. Some Arctic Terns, particularly on their northern breeding grounds, will also consume insects and occasionally berries.
Seasonal Dietary Changes
Arctic food availability fluctuates dramatically with seasons, prompting significant dietary shifts. During the brief Arctic summer, melting ice and snow lead to an explosion of life, increasing insect activity and plant matter. This abundance allows birds to build fat reserves crucial for winter. For instance, birds that primarily eat fish may switch to consuming berries and insects when their usual prey becomes scarce or inaccessible.
As winter approaches, food sources become much scarcer. Many species, like the Arctic Tern, undertake extensive migrations to areas with more consistent food supplies, such as the oceans around Antarctica. Resident birds’ winter diet is leaner, relying on energy accumulated during warmer months.
Specialized Foraging Strategies
Arctic birds have diverse methods and adaptations to acquire food. Many seabirds, including puffins, murres, and some gulls, are skilled divers, propelling themselves underwater to pursue fish and marine invertebrates. Atlantic Puffins, for example, dive to catch capelin, a large portion of their diet. Arctic Terns plunge-dive, hovering before snatching small fish or crustaceans near the surface.
Some species scavenge opportunistically. Ivory Gulls, for instance, are adept at scavenging around ice floes, feeding on carrion left by predators like polar bears. Glaucous Gulls also scavenge, often frequenting fishing ports and harbors during winter to feed on discards. This adaptability allows them to exploit any available food source in a resource-limited landscape.
Certain birds display cooperative foraging. Arctic Terns, during migration, forage in groups with other seabirds, following predatory fish that drive smaller fish to the surface. Other adaptations include specialized beaks for extracting food from snow or ice, or strong gizzards for digesting hard-shelled mollusks. These varied strategies underscore the ingenuity of Arctic birds.