The snowy plover is a small shorebird that lives primarily on beaches along the Pacific and Gulf coasts of North America. Despite their name, snowy plovers do not live in snowy or even particularly cold environments. Instead, they get their name from their mostly white plumage. Here are some key facts about these charismatic shorebirds:
Physical Appearance
Snowy plovers are tiny, weighing only 1.5-2.5 ounces (40-70 grams). Their bodies are about 6-7 inches (15-18 cm) in length. As their name suggests, the plumage on their backs, wings, and breasts is mostly white. They have a thin dark patch on the forehead and one behind the eye. Their legs are dark gray. Males and females look very similar, although females may have darker patches of color.
During breeding season, snowy plovers develop black markings on their foreheads and necks. Juveniles have speckled gray and brown feathers on their backs. These help the young birds camouflage on the sandy beaches where they live.
Range and Habitat
Snowy plovers live on coastal beaches from Washington state south to Baja California in Mexico. On the Atlantic side, they are found from North Carolina around the Florida coast and south to the Yucatan Peninsula. Their breeding range extends inland to southern states like Texas, New Mexico, and Oklahoma, as well as parts of the Midwest near the Great Lakes.
Snowy plovers nest right on wide, flat, sandy beaches with little vegetation. They prefer beaches undisturbed by heavy human recreation. Outside of breeding season, snowy plovers also inhabit tidal flats, sand flats, alkali lakes, and levees.
Diet
Snowy plovers forage for small invertebrates on beaches and mudflats. They eat insects like beetles, flies, midges, ants, grasshoppers, and moth larvae. They also feed on marine worms, crabs, shrimps, and snails.
Snowy plovers probe for prey with their short bills in the sand or mud. They also pick insects off of vegetation. Their salt gland allows them to drink seawater when freshwater is scarce.
Breeding and Nesting
The breeding season for snowy plovers starts in mid-March and runs through September. During courtship, the male scrapes out several small depressions in the sand, then leads the female to inspect them. Once she selects a nest site, the male continues preparing it by digging out an egg-shaped hollow and lining it with bits of shell, seaweed, pebbles, or other debris.
Snowy plovers lay 2-6 speckled, brownish eggs. Both parents incubate the eggs for about 25 days. The nests are very vulnerable to predators, weather, high tides, and human disturbance. Parent birds and eggs are well camouflaged, but humans can still easily step on nests by accident.
Chicks and Parenting
Snowy plover chicks are precocial, meaning they are mobile and can feed themselves shortly after hatching. However, they depend on their parents to lead them to suitable feeding habitat. Chicks walk and run almost immediately after hatching. Within hours, they are pecking at the ground for small prey.
Parents vigilantly brood their young and lead them to different foraging areas. Chicks communicate with soft peeping calls when they get separated from the adults. Both parents share brooding and feeding duties. Young plovers fledge and become capable of sustained flight at 4-5 weeks old.
Migration
Most snowy plover populations migrate between inland breeding areas and coastal wintering grounds. They breed inland across prairie regions from March to September. After breeding, they migrate to the coasts of California, Florida, Mexico and the Caribbean.
Snowy plovers that nest along the Pacific Coast often stay there year-round. They move short distances up and down the coast to find suitable habitat as seasonal conditions change.
Conservation Status
The western snowy plover population in the U.S. was listed as threatened under the Endangered Species Act in 1993. Habitat loss, predation pressure, and human disturbance have caused steep declines, especially in California where plovers once nested abundantly on wide beaches.
Pacific Coast breeding populations south into Baja California are considered endangered. Interior breeding populations have rebounded more successfully thanks to habitat protection and predator management.
Threats and Predators
The greatest threats to snowy plovers are habitat degradation and high rates of nest predation. Coastal development, beach grooming, and heavy recreation pressure impact breeding and foraging areas. Introduced beachgrass helps predators remain hidden when approaching plover nests.
Common nest predators include crows, ravens, coyotes, foxes, raccoons, skunks, ground squirrels, and feral cats. Plovers rely on camouflage and hiding to survive, so habitat quality strongly impacts rates of predation. Adults may perform distraction displays to lure predators away from chicks and eggs. When disturbed, snowy plover parents have been observed luring predators away with a feigned broken wing display.
Interesting Facts
– Snowy plovers are sometimes considered seabirds, yet they rely on terrestrial food sources more than marine ones.
– Their genus name Charadrius comes from the Greek for “ravine” or “torrent,” referencing their habitat preferences near inland streams.
– Snowy plovers occasionally ingest small pebbles, possibly to grind up food in their gizzard. They are one of only a few shorebirds known to intentionally ingest stones.
– Males establish scrapes in breeding territories and lead females through elaborate courtship rituals. Scrapes are essential to breeding in this species.
– Snowy plovers have one of the longest breeding seasons of any North American bird, nesting from March to September.
Distribution and Habitat
Snowy plovers are found along the Pacific and Gulf Coasts of North America, as well as in interior regions around alkaline lakes and flats in the southern half of the continent. Here is a more detailed overview of their distribution and habitat preferences:
Pacific Coast
Along the Pacific Coast, snowy plovers breed from southern Washington state south to Baja California, Mexico. Important breeding sites include coastal beaches and estuary shores in southern Washington, Oregon, and California. Some inland lakes and rivers, such as Goose Lake in Oregon, also host nesting plovers.
Outside of breeding season, Pacific coast populations may migrate short distances or even remain in the same general region if habitat remains suitable through winter. They frequent beaches, sand spits, dune systems, salt pans, and agricultural evaporation ponds.
Gulf Coast and Southeast
On the Gulf Coast, snowy plovers breed locally on sandy beaches from Florida to Texas and south into northeastern Mexico. Migration extends down the Yucatan Peninsula and Caribbean islands in winter.
Snowy plovers inhabit Gulf beaches, tidal flats, sandbars, inlets, saltpans, and shorelines around brackish lagoons and lakes. On the Atlantic coast, they nest north to North Carolina during summer.
Interior West and Great Plains
Significant breeding populations occur inland across prairie regions of Colorado, Kansas, Oklahoma and Texas. Scattered nesting extends north to Nebraska, Wyoming, Utah, Nevada and California. Habitat includes saline and alkaline lakes, wetlands, rivers, reservoirs, and flats with sparse vegetation.
Interior snowy plovers migrate coastally in winter, mixing with west coast populations. A small population winters around the Great Salt Lake in Utah.
Breeding Habitat
Snowy plovers require wide, flat spaces of bare or sparsely vegetated ground for nesting. Typical sites include ocean beaches, sand spits, dune systems, alkali flats, and sand or gravel bars along inland lakes, rivers, and reservoirs.
Nesting habitat must provide camouflage from predators. Snowy plovers avoid densely vegetated areas where predators can hide and approach unseen. Easy access to shallow water for chick feeding is also essential.
Wintering Habitat
In winter, snowy plovers flock together and occupy various coastal and inland habitats. Beach characteristics are less important than in summer. Plovers frequent beaches, tidal flats, lagoon shores, salt pans, evaporation ponds, sand and mud bars, and lake edges where they can forage.
They prefer sites with access to freshwater and marine invertebrate prey. Occasional inland records occur at reservoirs, lakes, and rivers.
Breeding and Reproduction
The breeding habits of snowy plovers have been well studied due to conservation concerns. Here are some key details about their breeding biology:
Pair Formation
Snowy plovers form monogamous breeding pairs, although polygamous groups sometimes occur. Males establish breeding territories in March or April and advertise to females with elaborate courtship displays. Courtship involves repetitive calls, posturing, and offering nest scrapes.
Nesting
Nesting starts from mid-March to early September, varying across the range. The male selects the nest site and scrapes multiple shallow depressions in the sand. The female chooses one and lines it with debris.
Nests are shallow, egg-shaped scrapes placed in open areas with good visibility. Vegetation, driftwood, and debris help provide cover. Symbolically lining the nest may encourage egg-laying.
| Location | Typical Nests Dates |
|---|---|
| Pacific Coast | Mid-March to mid-September |
| Gulf Coast | April to August |
| Interior West | Late April to early August |
Clutch Size
Typical clutch size is 3 eggs, with a range of 2-6. Snowy plovers produce one clutch per season, with rare cases of double brooding.
Eggs are tan or buff-colored with dark speckling. This provides camouflage against the sandy beach backdrop. Egg laying is usually 1-2 days apart. Replacements may occur if eggs are lost.
Incubation
Both sexes incubate the eggs for 22-31 days until hatching. Nest attendance drops temporarily during the hottest parts of the day. Pairs may change incubation duties every 6-12 hours.
Incubating birds sit very tight on the nest until approached very closely. They rely on camouflage to avoid predators. If startled off the nest, the adult may perform a distraction display.
Chicks
Snowy plover chicks are precocial. They are mobile soon after hatching and leave the nest within hours. Chicks feed themselves, but adults lead them to suitable habitat.
Brooding adults shade chicks from sun and high temperatures. Cool sand helps regulate chick’s body temperature. Chicks fledge at 30-35 days but remain with parents until migrating south.
Nest and Chick Mortality
Nest success averages around 40%, but widely varies by site from 0-70%. Flooding, predation, weather, human disturbance, and insufficient nest camouflage all increase failure rates.
Chick survival to fledging age also averages around 40%, with 0-70% among sites. Predators, weather exposure, lack of food, and human disturbance all increase chick mortality.
Population Status and Conservation
Snowy plover populations declined sharply in the late 20th century, leading to special conservation protections. Ongoing threats make their future uncertain.
Historic Populations
Historic snowy plover abundance is poorly known. An 1880 report estimated over 50,000 breeding birds in California. Along the Pacific Coast, populations likely numbered over 10,000 total adults into the mid 1900s before precipitously declining.
Population Declines
By the 1970s, Pacific Coast snowy plovers had declined 75-90% from historic numbers. Interior populations declined at least 30% in the same period. Overall declines stemmed from widespread habitat degradation and high nest/chick mortality.
In 1993, coastal western snowy plovers were federally listed as threatened under the Endangered Species Act.
Current Populations
Current breeding adults on the Pacific Coast number around 2,100. Oregon supports about 90 breeding adults, and California 1,300. Interior populations have rebounded better, with over 14,000 adults across the Great Plains and western regions.
| Region | Breeding Adults | Trend |
|---|---|---|
| Pacific Coast | 2,100 | Stable |
| Interior West | 14,000 | Increasing |
| Gulf Coast | 1,200 | Stable |
| Eastern Seaboard | 50 | Stable |
Threats
Habitat loss from development, recreation, and invasive plants remains a threat. Predators, vehicle traffic, oil spills, and human disturbance add pressures. Climate change may increase nest flooding.
Recovery requires secure habitat, predator control, public education, restrictions on recreation, and effective monitoring. Chick survival drives population trends, so strategies often focus on increasing hatching success.
Conservation Actions
Habitat protection and restoration, predator management, public outreach, enforcement of leash laws, symbolic fencing, and monitoring programs aim to aid snowy plover recovery. Population trends guide adaptive management strategies.
In Oregon, major nesting sites are fenced and signed. Leashed dog walking is promoted through ambassador programs. Volunteer docents educate beachgoers about plovers.
Behavior
Snowy plovers exhibit some interesting behaviors and adaptations for life in open, sandy coastal environments.
Foraging Behavior
Snowy plovers use visual hunting techniques adapted for flat, open terrain. They forage by sight, pecking swiftly when prey is spotted. Their salt gland allows them to drink seawater and excrete excess salt.
On coastal beaches, plovers probe into sea wrack along the high tide line. They pick exposed invertebrates from sand and vegetation. On mudflats, they rapidly peck at exposed prey between tidal cycles.
Plovers may soak their belly feathers to cool eggs or chicks. This releases water when brooding. They also lead chicks to moist sand for cooling.
Distraction Displays
When their nest or chicks are threatened, parent plovers perform distraction displays. They drag a wing on the ground, flutter awkwardly, limp, vocalize loudly, or feign injury. This draws attention away from the vulnerable young.
Some plovers learn to recognize individual humans or predators, only performing distraction displays if those particular threats approach. Otherwise, they rely on camouflage and sneaking off the nest.
Roosting
At high tide when beaches are inundated, plovers congregate to roost. Large groups roost communally in the open or next to logs, debris, or dunes. Birds stand, sit, or crouch closely together.
Communal roosting may provide safety benefits through more eyes watching for predators. It also aids thermal regulation when birds huddle together.
Scrapes and Rituals
Male plovers prepare symbolic nest scrapes in breeding territories to attract females. Scrapes are essential cues stimulating breeding behavior.
Males lead females through the scrapes with posture displays, then watch the female intensify a scrape before copulation. Nest scraping and lining is an important pair bonding ritual.
Long Distance Migrants
Most snowy plovers are long distance migrants, traveling over 1,000 miles between inland breeding sites and coastal wintering areas. Band resighting shows birds frequently move between the Gulf Coast and Pacific Coast across seasons.
Some plovers move over 2,000 miles between breeding sites in the Great Plains and wintering grounds along the Yucatan Peninsula and Caribbean islands.
Interactions with Humans
Snowy plovers face a variety of threats from human activities and coastal development pressures. Conservation requires managing these interactions.
Beach Recreation Impacts
Beach recreation such as off-leash dogs, vehicles, horseback riding, and fireworks disturb plovers and damage habitat. Symbolic fencing around nests has reduced but not eliminated impacts. Leash laws remain challenging to enforce.
Heavy recreation changes roosting and foraging habits. Birds flee more frequently, reducing feeding and resting time. Some plovers even abandon breeding sites if disturbance levels are too high.
Habitat Loss
Coastal development has eliminated or degraded snowy plover habitat through commercial and residential building, beach stabilization projects, and water diversion for human uses. Habitat loss increases predation rates and reduces reproductive success.
Removing European beachgrass helps restore wide, flat beaches used by plovers. Symbolic fencing protects dune habitats and prevents trampling. Access management strategies limit habitat degradation from vehicles and foot traffic.
Predator Management
High predation rates from crows, ravens, coyotes, foxes, skunks, raccoons, and feral cats significantly impact plover survival. Predator exclosures around nests provide temporary relief. Lethal removal remains controversial but helps increase productivity.
Predators are drawn to beaches by human food and garbage. Proper trash disposal and recycling reduces attractions for opportunistic predators. Leash laws prevent pets from disturbing and consuming plovers.
Climate Change
Rising sea levels may increase rates of overwash events and nest flooding. Expanding human populations could amplify coastal recreation pressure and development threats. Careful coastal planning helps provide habitat into the future.
Acquiring or protecting habitats inland may become more important if low-lying coastal sites are lost. Breeding sites far from the coast may experience less disturbance as human populations concentrate near oceans.
Recovery Challenges
Full recovery remains unlikely without intensive management of predators, recreation, and habitat degradation. Plovers require constant vigilance because of their camouflaged and easily impacted nesting strategy. Their habit of scraping small nest depressions in open areas is both a survival advantage and a liability.
Public education and outreach aim to build support for plover conservation, but funding limitations constrain recovery programs. Long term monitoring tracks population trends to guide adaptive management.
Research Priorities
Many aspects of snowy plover biology and conservation needs remain poorly understood. Future research priorities should address these knowledge gaps.
Breeding and Wintering Connectivity
Banding studies show interconnectivity between Pacific, Gulf, and Atlantic coasts during migration and winter. More tracking is needed to elucidate connections between specific breeding and wintering sites across the contiguous range.
Population Genetics
Genetic analyses may reveal how inbred Pacific Coast populations are following isolation and declines. Connectivity with interior and Gulf Coast birds could provide an influx of genetic diversity needed for resilience.
Climate Change Impacts
Snowy plovers are vulnerable to sea level rise, changing ocean temperatures, increasing storm severity, and escalating development pressure. Studies should examine population viability and coastal habitat trajectories under different climate scenarios.
Human Disturbance Thresholds
Recreation pressure on beaches continues growing, but thresholds remain unclear for when disturbance significantly impacts snowy plover populations. Additional studies should identify tipping points useful for management.
Predator Interactions
Predator identity, behavior, and removal efficacy need further research to maximize management success. Predator dynamics may differ between wintering and breeding sites in important ways.
Conclusion
In conclusion, the threatened snowy plover faces ongoing conservation challenges across its coastal breeding and wintering range. Habitat loss, high predation, and human recreation impacts have caused steep population declines, especially along the Pacific Coast. Intensive management of nesting and wintering sites is required to stabilize populations, including predator control, habitat restoration, enforced leash laws, and public outreach. Chick survival drives population viability, so strategies often focus on increasing hatching success. If protections falter, snowy plovers risk continued declines or even extinction in parts of their range, especially on small islands. Maintaining coastal ecosystem health will allow snowy plovers to continue their unique breeding behaviors and long distance migrations up and down the Pacific Coast for generations to come.
