The long-billed dowitcher is a medium-sized shorebird that is found across North America. It gets its name from its long, probe-like bill that it uses to search for food. Long-billed dowitchers have a very specialized diet that allows them to thrive in wetland habitats. In this article, we will explore what long-billed dowitchers eat and how their specialized bills allow them to find food.
What do long-billed dowitchers eat?
Long-billed dowitchers are specialized predators that mainly eat small invertebrates. Their diet consists primarily of:
– Aquatic insects – Fly larvae, beetle larvae, dragonfly larvae
– Crustaceans – Shrimp, amphipods, isopods
– Mollusks – Snails, clams
– Worms – Earthworms, polychaete worms
They use their long bills to probe into muddy substrates to find these small invertebrates to eat. Their specialized diet means they occupy a unique niche in wetland habitats.
How do they find food with their specialized bills?
The long, tapered bill of the long-billed dowitcher allows it to hunt for food very efficiently:
– Their bills can reach up to 3 times the length of their heads, allowing them to probe deep into mud to reach food.
– Their bills have sensitive nerve endings at the tip that allow them to detect prey items hidden in mud or vegetation.
– They have a sewing-machine like feeding action, rapidly opening and closing their bills while probing to grab hidden food.
– Their long bill provides leverage to dig into soft substrates and lift out food items.
– They also have a flexible bill joint that allows the bill to open wider when a prey item is detected.
This specialized bill morphology equips them perfectly for their tactic of probing for hidden prey in wet sediments. It allows them access food sources many other birds cannot reach.
How do they eat?
Long-billed dowitchers employ a unique feeding technique:
– They wade through shallow water or along wet shorelines probing their bill into the substrate.
– When they detect prey with their sensitive bill tips, they rapidly open and close their bill to grab the food item.
– They use a scything motion side to side to probe larger areas.
– Sometimes they will also do a foot trembling behavior to stir up prey in soft sediments.
– Once prey is captured, they lift their head up and swallow the food item whole.
– They don’t chew or process food in their bills since they swallow food items whole.
Their rapid probing combined with their highly sensitive bills allows them to quickly and efficiently find and consume many small prey items. This gives them ample nutrition to migrate long distances and survive through harsh winters.
What adaptations help them find food?
In addition to their specialized bill, long-billed dowitchers have other adaptations to help them find food:
– Their eyes are positioned high and to the sides of their head, giving them a panoramic view to spot prey while probing.
– They have cryptic plumage patterns that allow them to blend into wetland habitats, getting close to prey.
– Their bodies are compact and low-slung which reduces silhouette while wading and probing.
– They have long legs perfect for wading through mud while hunting.
– Their feet have partially webbed toes to give them stability while walking through mud.
– They have dense, soft feathers that repel water and keep them insulated while wading.
These physical and behavioral adaptations allow long-billed dowitchers to thrive in shallow wetland areas that provide plentiful invertebrate prey.
Where do they forage for food?
Long-billed dowitchers forage for food in very specific wetland habitats:
– Shallow ponds, marshes, and flooded fields provide optimal probing conditions.
– Mudflats, estuaries, and shorelines that experience tidal fluctuations.
– Ditches, streams, and flooded agricultural fields.
– Wetlands with some vegetation like grasses or reeds provide cover.
– They prefer areas with soft, probing substrates like mud or fine sand.
These wetland habitats hold high densities of the aquatic invertebrates that the dowitchers feed on. The soft substrates also allow them to easily probe for food.
What is their foraging behavior?
Long-billed dowitchers exhibit very specialized foraging behaviors:
– They wade through shallow water probing constantly.
– They probe rapidly, up to 240 times per minute.
– They snap their bills open and closed in a sewing machine-like action while probing.
– They keep their bill submerged in the substrate while probing.
– They swing their bill from side to side in a scything motion to cover more ground.
– They sometimes use foot trembling to stir up prey from sediments.
– They form large feeding flocks that forage together to find rich food sources.
Their constant probing while wading through wetlands allows them to find small prey that other birds cannot access. Foraging in large flocks may also help them locate the best feeding areas.
How does their diet change seasonally?
The diet of long-billed dowitchers changes across seasons:
| Season | Diet |
|---|---|
| Winter | More mollusks and crustaceans |
| Summer | More aquatic insects and larvae |
| Migration | Opportunistic – eats what is available in stopover wetlands |
| Breeding | Wider variety including berries and seeds |
In winter they rely more on mollusks and crustaceans which are available year round. In summer, they eat more plentiful insects. During migration they eat whatever prey is available, and while breeding they supplement with berries.
How much do they eat daily?
Long-billed dowitchers spend the majority of their time foraging. They likely eat almost constantly while foraging to meet their high energy needs:
– They eat an estimated 70% of the time during winter.
– They consume a wide variety of small prey including worms, mollusks, insects, crustaceans.
– Individuals likely consume 40 to 60 grams of food daily.
– Their intake increases to around 100 grams daily before migratory periods.
– They have exceptionally high metabolisms, requiring vast energy intake.
Their rapid probing allows them to find food nearly continuously to meet these high intake needs. Their specialized feeding allows them to flourish in habitats rich in invertebrate prey.
What if they can’t find food?
If long-billed dowitchers are unable to find sufficient food it can be detrimental:
– They have limited energy reserves due to their high metabolism.
– If wetland stopover sites during migration lack food, they may not refuel adequately for their long flights.
– Lack of food can cause reductions in body mass leading to lower survival.
– They are forced to move elsewhere to find more productive foraging sites.
– In very dire conditions, individuals may perish due to lack of food.
– Food shortages make them more susceptible to predators since they weaken.
Fortunately, long-billed dowitchers are resourceful foragers and excellent fliers allowing them to pioneer new habitat if needed to find sufficient food resources. But degradation of wetland stopovers could potentially impact their populations through food limitations.
How does food availability impact their migrations?
Food availability at migratory stopover sites directly impacts long-billed dowitchers:
– They cannot successfully migrate if stopover sites lack adequate food.
– Quality wetland stopovers with abundant invertebrates allow them to quickly rebuild energy stores for the next migratory leg.
– If food is scarce, they may be forced to stay longer than optimal at a stopover site to find food. This slows migration.
– Low food extends stopovers and increases chances of predation.
– Abundant food resources allow them to shorten stopovers and migrate faster.
– They may skip stopover sites completely if food resources are inadequate.
Productive wetlands with rich food resources are crucial for these long-distance migrants. Loss of quality stopover wetlands threatens their migration success.
Conclusion
In conclusion, long-billed dowitchers are highly specialized predators with a diverse diet of small aquatic invertebrates. Their unique bill morphology and foraging behaviors allow them to feed efficiently on hidden prey in wetland sediments. Abundant food resources in productive wetland habitats are critical to allow these migratory birds to replenish energy stores needed to complete their long journeys. Loss of wetland stopover sites and degradation of foraging habitat threatens the future of these specialized feeders. Understanding details of their feeding ecology provides insights into management practices needed to maintain healthy dowitcher populations into the future.
