Godwits are medium to large sized shorebirds that belong to the genus Limosa. There are around 10 different species of godwits that can be found across the globe, most of which inhabit coastal wetlands and mudflats. Godwits have long legs, long bills, and long necks which help them probe deep in mud or sand to find food. Their diet consists primarily of invertebrates such as worms, mollusks, crustaceans, and insects. The exact composition of their diet can vary depending on habitat, season, and species.
Worms
Worms make up a significant part of the diet for most godwit species. They use their long bills to probe down into wet mud or sand and snatch up worms to eat. Some of the worm species commonly eaten include ragworms, lugworms, sandworms, and earthworms. The availability of worms in their habitat is one factor driving when and where godwits migrate and feed. When the tides go out and expose mudflats, godwits can take advantage of the access to feed on worms. Godwits like the Bar-tailed Godwit may consume worms during migratory stopovers to quickly rebuild energy reserves needed to continue their long journeys.
Mollusks
Godwits also feed extensively on mollusks, relying on their specialized bills to pry open shells and access the soft body within. They eat a variety of small mollusks including snails, clams, mussels, and oysters. For example, the Hudsonian Godwit eats mollusks like Macoma clams that live buried in the intertidal mud. The Marbled Godwit probes for and consumes mollusks like mud snails that emerge to feed during low tides. Godwits are resourceful foragers and have even been documented opening up shellfish aquaculture gear to eat farmed oysters and clams.
Crustaceans
Crustaceans like crabs, shrimp, and amphipods are another key prey item in the godwit diet. Godwits forage for crustaceans around tidal flats, estuaries, lagoons, and beaches, probing their bills into the substrate and water to catch their prey. Small crabs are consumed by godwits like the Marbled Godwit on feeding grounds along the northern Pacific Coast. Godwits like the Bar-tailed Godwit also eat saltwater shrimp during migratory stopovers to fuel up. Their specialized bill shape likely helps them capture fast moving crustacean prey.
Insects
Aquatic and terrestrial insects are sometimes eaten by godwits depending on habitat and availability. For example, the Black-tailed Godwit consumes insects like beetles, dragonflies, and caddisflies when breeding in freshwater wetlands. The Bar-tailed Godwit eats brine flies and larvae in intertidal areas. Godwits may catch flying insects in the air and on the ground. Insects provide an important source of protein for developing chicks. Adult godwits also opportunistically feed on insects to supplement their diet, especially in inland habitats.
Other Prey
In addition to the main prey items already covered, godwits also occasionally eat other invertebrate prey. Some other foods include polychaete marine worms, nestling birds, fish eggs, spiders, centipedes, and more. The wide range of prey items reflects the godwit’s ability to adapt and take advantage of locally abundant food sources. Their diverse diet provides nutrition and helps ensure they can find sufficient food across habitats during their migratory cycle.
Differences Between Species
While the general diet of worms, mollusks, insects, and crustaceans is consistent across godwit species, there are some differences in prey preference between them. These differences arise from variations in bill morphology and geographic distribution. For example, the Bar-tailed Godwit has a longer, more slightly upturned bill suited for probing deeply in mudflats for worms. In contrast, the Marbled Godwit has a shorter, straighter bill ideal for capturing crabs, mollusks, and other prey in shallow water. Geographic separation also influences prey availability. The Black-tailed Godwit breeds in freshwater wetlands where it can access insects and annelid worms, while the Hudsonian Godwit eats mollusks in coastal Arctic tidal flats during migration.
Habitat and Feeding Behavior
Godwits employ a variety of foraging methods to find and capture prey across tidal flats, estuaries, beaches, inland wetlands, flooded fields, and shorelines. Wading in shallow water, they probe their long bills into the mud or sand to grab buried worms, mollusks, and other prey by touch. They also visually hunt for prey at the surface, spearing or pecking to capture items. Sometimes godwits will shuffle their feet to disturb the sediment and flush out prey. On their breeding grounds, godwits hunt prey in grasslands and agricultural fields. Godwits exhibit high site fidelity, returning to profitable feeding locations year after year during their migrations.
Diet Composition by Prey
Prey Type | Percentage of Diet |
---|---|
Worms (annelids) | 30% |
Mollusks | 25% |
Crustaceans | 15% |
Insects | 15% |
Other invertebrates | 10% |
Fish eggs | 5% |
This table provides a rough breakdown of the estimated composition of prey in the overall godwit diet. As seen, annelid worms such as ragworms and lugworms make up the largest percentage at around 30% of their total food intake. Mollusks and crustaceans each makeup about 25% and 15%, while insects comprise around 15% as well. The remaining small percentage consists of other prey like fish eggs, spiders, marine worms, and so on.
Diet Composition by Species
Godwit Species | Primary Prey |
---|---|
Bar-tailed Godwit | Marine worms, mollusks, brine shrimp |
Black-tailed Godwit | Insects, worms, mollusks |
Hudsonian Godwit | Mollusks, marine worms, insects |
Marbled Godwit | Crabs, mollusks, polychaetes |
This table summarizes the primary prey types eaten by different godwit species. While their diets overlap, some preferences exist. For example, the Marbled Godwit consumes more crabs and mollusks, while the Bar-tailed Godwit feeds heavily on marine worms and brine shrimp. The Black-tailed Godwit takes more insects than others when breeding in inland habitat.
Seasonal Variation
Godwits exhibit some seasonal shifts in diet linked to migration, breeding, and changes in prey availability throughout the year. During the breeding season, godwits may consume more terrestrial insects to provide high protein foods for rapidly growing chicks. At migratory stopover sites, godwits gorge on readily available food like marine worms to quickly rebuild energy stores for continued migration. Some prey becomes more abundant in warmer months, leading godwits to take advantage of these temporary food sources. Overall, godwits display dietary flexibility and can adapt to seasonal changes in prey availability.
Conclusion
Godwits are remarkably adapted for probing into mud and sand to capture prey. Their primary diet consists of worms, mollusks, crustaceans, and insects. Prey preferences vary somewhat based on habitat, season, and godwit species. But overall, godwits are opportunistic feeders able to take advantage of locally abundant food sources across their range. Their specialized bills allow them to hunt a wide variety of prey buried in wetland sediments or moving through shallow coastal waters.