Snowy plovers are small shorebirds that live on beaches along the Pacific and Gulf coasts of North America. Their diets consist mainly of invertebrates that they find along sandy shores and tidal areas. Here is an overview of the snowy plover’s diet and foraging habits.
Invertebrates
Snowy plovers are visual foragers that eat a variety of invertebrates along ocean shorelines. Their main prey items include:
- Mole crabs
- Marine worms
- Fly larvae
- Beetles
- Sand hoppers
- Shrimp
- Other small crustaceans
Mole crabs, also known as sand crabs, are a favorite prey. Snowy plovers use their beaks to probe into the sand in search of mole crabs and extract them quickly before they can burrow down into the sand to hide.
Sand hoppers and fly larvae are also common prey. They pick these small invertebrates from tidal wrack lines where plant debris accumulates along the shore.
Foraging Behavior
Snowy plovers employ a run-stop-peck foraging style as they scan for prey along beaches. They will run a few steps, stop to look for movement that indicates prey, and then peck quickly to catch invertebrates they detect along the surface.
Their foraging activity typically corresponds with the tidal schedule, with intensified feeding around low tide periods when prey is most exposed. At high tide, they will roost and rest.
Snowy plovers have several adaptations that help them find and catch prey on sandy shores, including:
- Large eyes positioned high on their heads give them good visibility while walking.
- Sparse feathers around their eyes reduce glare while searching.
- A short, stout beak allows them to make quick jabs into the sand.
- Partially webbed feet provide traction on soft sand.
Diet Composition
Researchers have analyzed the contents of snowy plover chick’s stomachs to understand their diets. The relative composition of prey found in one study was:
Prey Item | Percentage of Diet |
---|---|
Fly larvae | 48% |
Mole crabs | 28% |
Beetles | 12% |
Sand hoppers | 8% |
Spiders | 3% |
Other | 1% |
The composition can vary geographically and seasonally depending on prey availability. However, fly larvae, mole crabs, beetles, and sand hoppers consistently dominate.
Drinking
Snowy plovers meet most of their water needs from the body fluids of the invertebrates they eat. However, they will also drink small amounts of water from rain puddles, tidal pools, or edge areas where waves wash over the shore.
Being able to meet water needs from their food allows snowy plovers to inhabit arid beaches that receive little freshwater input.
Foraging Habitat
Snowy plovers forage almost exclusively on open sandy beaches along the coast. They prefer beaches with the following characteristics:
- Wide areas of surf-cast beach wrack containing tidal debris where invertebrates congregate.
- Sparse vegetation and dune structure, allowing them to move freely and spot prey.
- Gently sloping tidal areas with moist sand where prey is accessible.
- Availability of estuary mouths, lagoons, or river outlets that provide tidal flats rich in invertebrates.
Snowy plovers will avoid rocky intertidal areas or steep beach profiles since these habitats make prey more difficult to access. They are also more abundant on beaches with limited human disturbance.
Brood-Rearing
Chicks begin foraging on their own within hours after hatching. Parents do not provide any direct food for young. The chicks follow adults to feeding areas and learn to peck and probe for invertebrates.
Snowy plover chicks eat smaller prey items than adults, selecting tiny crustaceans, fly larvae, beetles, and other small beach invertebrates. Their foraging skills improve rapidly with experience.
Seasonal Variation
Snowy plover diets can shift across seasons in response to changing prey availability. For example:
- Spring may see increased mole crabs and fly larvae from larval hatches.
- Sand hoppers and shrimp increase in summer with warmer water.
- Late summer and fall see beetles, larval flies, and spiders emerge in beach wrack.
- Worms and mole crabs remain available in winter.
Snowy plovers are flexible and opportunistic foragers. They will readily switch prey preferences based on localized abundance.
Digestion
Snowy plovers have short, simple digestive tracts well suited to digesting invertebrates. Their stomachs can contract strongly to crush shelled prey items. Digestive enzymes and acidic stomach secretions allow them to fully digest chitinous exoskeletons.
The small seeds sometimes ingested with prey pass through their digestive systems intact and can even germinate after being excreted. This helps plovers play a role in distributing plants along the shoreline.
Predators
While foraging, snowy plovers must remain vigilant for predators. Their camouflaged plumage provides some protection, but they remain vulnerable, especially chicks. Major predators include:
- Falcons – Specialize in grabbing plovers in mid-run.
- Hawks – Hunt plovers from high vantage points.
- Owls – Use stealth ambush techniques.
- Gulls – Forage in similar habitats.
- Ravens – Corvids are intelligent opportunistic hunters.
- Coyotes – Take eggs or adults.
- Foxes – Specialize in nest raids.
When a predator is spotted, plovers give alarm calls and may mob or distract predators to let their chicks escape into vegetative cover. Parents have been observed providing themselves as decoys to divert predators away from chicks.
Human Impacts on Foraging
Human activities on beaches can negatively impact snowy plover foraging and prey availability. Some concerns include:
- Beach grooming removing wrack reduces invertebrate habitat.
- Off-road vehicles crushing prey burrows.
- Pollution and plastics interfering with feeding.
- Increased disturbance from recreation.
- Introduced beachgrass altering habitat and food webs.
Careful management is required to balance human beach use with protection of sensitive ecosystems that shorebirds rely on.
Conclusion
Snowy plovers are highly adapted to locate and catch small invertebrates in the constantly moving sands of coastal beaches. They play an integral role in these ecosystems as predators of numerous invertebrates. Conservation of sandy beach ecosystems with minimal human impacts will be essential to preserving the snowy plover’s specialized foraging habitat and food sources into the future.