Dowitchers are medium-sized shorebirds that belong to the genus Limnodromus. There are three species of dowitchers: the short-billed dowitcher, the long-billed dowitcher, and the Asian dowitcher. Dowitchers have long bills that they use to probe in mud or sand to catch prey. Their diet consists mainly of invertebrates that live in wetland habitats. Let’s take a closer look at what each species of dowitcher eats.
Short-billed Dowitcher
The short-billed dowitcher (Limnodromus griseus) is found in North America. This dowitcher gets its name from its relatively shorter bill compared to other dowitcher species. The short-billed dowitcher’s diet consists primarily of:
- Aquatic insects and insect larvae – Fly larvae, mayfly larvae, dragonfly larvae, damselfly larvae, caddisfly larvae
- Mollusks – Snails, clams, mussels
- Worms – Earthworms, polychaete marine worms
- Crustaceans – Amphipods, isopods, shrimp, crabs
- Other invertebrates – Leeches, flatworms, beetles, aquatic caterpillars
Short-billed dowitchers use their long, sensitive bill to probe into the mud or sand at the edge of ponds, lakes, wetlands, and tidal flats searching for prey. They swish their bill back and forth to stir up organisms and then use their tactile bill tip to detect and grab prey items. Their bill also has a slight bend allowing them to probe deeper into substrate. Short-billed dowitchers mainly eat small invertebrates found in or on top of wetland sediments. Aquatic insect larvae, worms, and mollusks make up the bulk of their diet.
Long-billed Dowitcher
The long-billed dowitcher (Limnodromus scolopaceus) is similar to the short-billed but has a longer, straighter bill. Long-billed dowitchers breed in northern Canada and Alaska and winter along the Pacific and Atlantic coasts of North America. This species eats a wide variety of invertebrate prey including:
- Insects – Fly larvae, mayflies, caddisflies, dragonflies, damselflies
- Worms – Earthworms, polychaete worms, nematodes
- Mollusks – Snails, bivalves, limpets
- Crustaceans – Shrimp, amphipods, isopods, crabs
- Other invertebrates – Leeches, flatworms, water bears
The long-billed dowitcher uses its long, straight bill to probe deeply into wetland sediments searching for prey. The bill’s length allows it to access a greater variety and volume of invertebrates buried more deeply in the mud. The extra length also gives the long-billed dowitcher an advantage when water levels fluctuate. During high water, prey items get dispersed over a greater area but this bird can still reach them with its elongated bill. Their specialized bill tip has a series of sensitive nerve endings that allow the dowitcher to detect slight vibrations and movements of potential prey under the substrate.
Asian Dowitcher
The Asian dowitcher (Limnodromus semipalmatus) is found in eastern Asia. It is the least studied of the three dowitcher species. From limited observations, the Asian dowitcher’s diet seems to consist mainly of:
- Insects and insect larvae – Beetles, dragonflies, craneflies, midges
- Worms – Polychaete worms, bristle worms
- Mollusks – Small clams and snails
- Crustaceans – Mud shrimp, amphipods
Like the other dowitchers, the Asian dowitcher uses its long bill to probe into wet sediments and sweep through vegetation in search of invertebrates. More research is still needed on the specific feeding behaviors and detailed diet preferences of this dowitcher species.
Feeding Behaviors
Dowitchers exhibit some interesting feeding behaviors and adaptations:
- They use a sewing machine-like motion, rapidly jabbing their bill into the substrate.
- Their bill tip is flexible and sensitive, allowing them to detect buried prey.
- They have a rear-facing fringe of feathers along the back of their legs that may help flush or trap prey.
- Dowitchers migrate long distances from breeding to wintering grounds where food is more abundant.
- They feed mostly at night or early morning when prey may be more active.
- Their salt glands allow them to drink saltwater and feed in marine habitats.
Dowitchers may sometimes employ a feeding method called “stitching” where they walk slowly, probing the ground in a straight line. This allows them to methodically cover an area to root out prey. Dowitchers also occasionally pick food items from the surface, but probing subsurface is their main feeding technique.
Breeding vs Non-breeding Diet
During the breeding season, dowitchers inhabit inland freshwater wetlands. Their prey items consist of insects, larvae, worms, mollusks and other invertebrates found in these habitats. After breeding, they migrate to coastal areas where they utilize intertidal mudflats rich in marine invertebrates. Their non-breeding diet expands to include more crabs, shrimp, marine worms and mollusks. The varied landscapes dowitchers occupy throughout the year expose them to a wide diversity of prey. Their generalized invertebrate diet allows them to thrive in these changing environments.
Role as Prey
While dowitchers feed on a variety of invertebrates, they also serve as prey for larger predators. Possible predators of dowitchers include:
- Foxes
- Coyotes
- Raccoons
- Mink
- Hawks
- Eagles
- Gulls
- Crows
- Ravens
Dowitchers rely on camouflage and cryptic behavior to avoid predators when feeding. Their brown, streaked plumage blends in well with the muddy shoreline habitats where they forage. During the breeding season, nesting dowitchers exhibit distraction displays leading predators away from nests. The inconspicuous eggs and chicks are well-camouflaged in their environment as well. When threatened, dowitchers may also take refuge in water too deep for predators to reach.
Unique Adaptations for Feeding
Over the course of evolution, dowitchers have developed some remarkable adaptations to their specialized feeding strategy:
- Oversized eyes are positioned high on their head giving excellent downward binocular vision for detecting prey while probing.
- Nostrils are slit-like to keep out debris while probing in sediment.
- Flexible bill tip packed with sensory pits detects slightest vibrations and movements.
- Serrated edges of bill help grip slippery prey like worms and larva.
- Long tongue coated in sticky saliva quickly catches and extracts prey.
- Salt glands near eyes remove excess salt from marine prey and seawater.
Additionally, the location of their legs and feet on their body is optimized for balance and stability in soft substrates. These specialized traits all contribute to the dowitchers’ efficient and effective feeding strategy tailored to probing wetland sediments.
Conclusion
Dowitchers employ a unique feeding method of probing into muddy substrates to target concealed invertebrate prey. Their diverse diet includes insects, worms, mollusks, crustaceans and other organisms found in aquatic sediments and vegetation. While the three species vary slightly in bill length and geographic range, they all share common feeding behaviors and adaptations to probe-feeding. Dowitchers migrate long distances across continents to take advantage of seasonally abundant food resources. Their role as prey also adds to the interconnectedness of wetland food webs. The dowitchers’ sensitive bill, cryptic plumage and specialized adaptations make them highly efficient at exploiting wetland food sources across North America and Asia.
