The Spotted Sandpiper (Actitis macularius) is a small, migratory shorebird that breeds across most of Canada and the northern United States. It is characterized by its distinctive bobbing motion when walking, as well as the spotted pattern on its breast and belly during breeding season. Some quick facts about the Spotted Sandpiper:
- Length: 18-20 cm
- Wingspan: 34-38 cm
- Weight: 40-65 g
- Lifespan: Up to 11 years
- Conservation status: Least Concern
In this article, we will explore the key physical characteristics, behavior, breeding habits, habitat, diet, and conservation status of the Spotted Sandpiper. Understanding the unique traits of this shorebird provides insight into its role within wetland ecosystems.
Physical Characteristics
The Spotted Sandpiper is a small-medium sized shorebird, measuring 18-20 cm in length with a wingspan of 34-38 cm. Some key physical features include:
- Size: Weighs 40-65 g. Males and females are similar in size.
- Plumage: Dark brown above with white underparts. Small white spots on the wings and back. Bright white patches on the tail under the wings. Dark streaking on the breast during non-breeding season.
- Spots: Distinctive black spots cover the breast and belly during breeding season. The spots are hormonally controlled.
- Bill: All black, medium length, and slightly upturned.
- Legs: Yellowish legs and feet.
- Sexual dimorphism: Males and females look alike.
The spotted plumage on the underparts helps give this bird its common name. The spotted pattern provides camouflage for the sandpiper and its eggs during the breeding season. Outside of breeding season, the spots disappear and the bird returns to its plain gray-brown plumage.
Behavior
The Spotted Sandpiper exhibits some interesting behaviors and mannerisms:
- Bobbing motion: Constantly bobs its tail up and down, a distinctive feature of this species.
- Flight: Alternates rapid wing beats with brief glides. Often flies low over the water.
- Foraging: Walks along mudflats and shorelines, probing for food. Also wades in shallow water.
- Vocalizations: Sharp ‘peet-peet’ whistles. Softer ‘teet’ calls during flight.
- Solitary: Usually seen alone, does not form flocks like some sandpipers.
- Aggressive: Highly territorial, will chase other shorebirds from its nesting site.
- Migratory: Summers across Canada/Northern U.S. Winters in South America.
The constantly bobbing tail is thought to distract and lure potential predators away from the nest. The bird often repeats its harsh ‘peet’ call when alarmed. Spotted Sandpipers become much more aggressive and territorial during breeding season.
Breeding
The breeding season for Spotted Sandpipers runs from May to August across their northern range. They have some unique breeding behaviors:
- Polyandry: Females breed with several males in a season.
- Males incubate eggs: An uncommon role reversal in birds.
- Solitary nesting: Each female has its own nesting territory.
- Nest on the ground: Scrape nests built on bare dirt near water.
- 4 eggs per clutch: Lays up to 4 heavily spotted eggs.
- Chicks precocial: Chicks mobile soon after hatching.
The female initiates courtship rituals with a flight display and mating occurs on the ground. The female will then lay eggs in multiple male’s nests across her territory, often with days between each clutch. The males alone incubate the eggs and care for the precocial young. This reproductive strategy helps ensure the female’s offspring survive, even if some nests are lost.
Nesting and Egg Laying
Nesting begins in May or June depending on latitude. The nest consists of a simple scrape in an open, rocky area near water. Nest materials may include grasses, leaves, pebbles or shells.
Females lay 4 pear-shaped eggs over 4-5 days. The eggs are pale with heavy brown spotting that helps camouflage them. Incubation lasts 20-22 days and hatching is staggered.
Parental Care
Parental care in Spotted Sandpipers is unique compared to most other birds. The female leaves eggs in the care of the male and flies off to find a new mate. This polyandrous system means each female may breed with up to four males in one season.
The male sandpiper incubates the eggs and cares for the precocial young on his own. He shelters them from weather and predators for up to three weeks until they fledge. By breeding with multiple males, the female maximizes the chance of successful offspring production.
Habitat
Spotted Sandpipers breed in a variety of wetland habitats in their northern range:
- Pond and lake shores
- Streams and rivers
- Coastal wetlands
- Mudflats and sandbars
They favor areas with bare, open ground for nesting near water. During migration and winter they occupy:
- Coastal mudflats and tidal zones
- Flooded fields
- Saltwater and freshwater marshes
- Mangroves
Access to shallow water for foraging is a key habitat requirement year-round. They are sensitive to disturbance and will abandon nest sites with too much human recreation or traffic.
Territory
During breeding season, both male and female Spotted Sandpipers become territorial and defend discrete areas. Territory size varies:
- Males defend up to 2 hectares along a stretch of shoreline
- Females occupy larger territories up to 20 hectares in size
These territories provide sufficient feeding areas and access to safe nest sites. Both sexes become aggressive during breeding and will try to chase away intruders entering their space.
Migration
Spotted Sandpipers undergo a long-distance migration each year between their northern breeding grounds and wintering areas:
- Spring migration north runs from mid March to May
- Fall migration south occurs September to November
- Travel up to 5,500 km between seasons
Migration occurs at night and the birds cover large distances rapidly. They stop to rest and feed in wetlands along migration pathways. While in transit they congregate in loose flocks at optimal stopover sites.
Diet
Spotted Sandpipers forage actively using a distinctive teetering motion. Their diet consists of small invertebrates and insects:
- Worms
- Mollusks
- Crustaceans
- Larvae
- Flies
- Mosquitoes
- Beetles
- Spiders
They probe mud and shallows for prey, or quickly snatch insects from vegetation. The long bill helps them pluck food from the subsurface. While foraging, they occupy both aquatic and terrestrial habitats.
Here is a table summarizing the Spotted Sandpiper’s diet composition by percent:
| Prey Type | Percent Composition |
|---|---|
| Insects | 50% |
| Worms | 30% |
| Mollusks | 10% |
| Crustaceans | 5% |
| Other | 5% |
As shown, insects make up half their diet. Aquatic and terrestrial insects are major sources of nutrition for Spotted Sandpipers across their range.
Foraging Behavior
Spotted Sandpipers use a variety of foraging techniques:
- Probing: Insert bill into mud or sand to catch buried prey.
- Pecking: Strike quickly at insects on the ground or vegetation.
- Gleaning: Pluck prey items from shoreline plants.
- Seizing: Snap up insects from water surface.
Their tactile bill is equipped with special nerve endings to detect prey hidden in sediment. They display good visual acuity to spot insects on both land and water.
Preferred Foraging Habitats
Spotted Sandpipers forage primarily in shallow freshwater environments:
- Lake edges
- Slow moving streams
- Marshy wetlands
- Muddy shorelines
Access to exposed mudflats, riffles, or wet grasslands rich in insect life are key foraging habitats. They avoid foraging in deeper waters. At high tide they forage on upper beach areas.
Conservation Status
The Spotted Sandpiper has an extensive range and large global population. According to the IUCN Red List, it is classified as a species of Least Concern. However some key conservation issues face the species:
- Population declined by around 15% between 1966-2015
- Habitat loss due to wetland drainage
- Disturbance of nesting sites
- Pollution and pesticides reducing prey
- Climate change altering wetland hydrology
Maintaining suitable shoreline habitat with protected breeding areas will be important for long-term conservation of Spotted Sandpiper populations. Monitoring is needed to detect future declines in numbers.
Population and Distribution
Global population estimates include:
- Total population: 2.2 to 3.5 million birds
- Extent of occurrence: 4.9 million square km
Spotted Sandpipers breed across most of North America:
| Region | Population |
|---|---|
| Canada | 100,000 to 500,000 pairs |
| USA | 1 million to 2.5 million pairs |
| Mexico | 100,000 to 1 million pairs |
| Central America | 100,000 to 1 million pairs |
The largest populations breed across Canada and Alaska. Populations winter along coasts of Central and South America.
Threats
Some specific threats and conservation issues facing Spotted Sandpipers:
- Habitat degradation – Draining and filling of wetlands
- Human disturbance – Recreational use near nesting areas
- Pollution – Pesticides reduce insect prey availability
- Climate change – Changes to hydrology, sea level rise
- Predation – Increased predators near habitats
Conservation efforts should focus on protecting wetland habitats, managing recreational activities, and limiting use of pesticides. Climate change resilience through wetland restoration is also beneficial.
Conclusion
In summary, the Spotted Sandpiper is a unique shorebird known for its bobbing motion, solitary breeding habits, and spotted plumage. Identifying characteristics include its size, dark brown colors, spotted underparts, yellow legs, teetering movements, and ‘peet’ call.
Spotted Sandpipers breed in wetlands across North America during summer before migrating long distances to South America each winter. Males solely incubate the eggs and raise the precocial young. These sandpipers forage by probing in mud flats for worms and other invertebrates.
Conservation efforts should aim to protect suitable wetland habitats and limit disturbance in breeding areas. With appropriate habitat conservation, the adaptable Spotted Sandpiper remains common across its broad range. This species serves as an indicator of healthy shoreline ecosystems.
