Spotted Sandpiper––a shorebird with standout looks and behavior

Perhaps you have noticed a small shorebird constantly bobbing its backend as it works its way along the edges of our local streams and ponds.

Other shorebirds might not grab your attention, but the spotted sandpiper catches your eye with its nonstop teetering motion and distinctive dark spots on its white breast.

This shorebird is a handsome standout in the lineup of small, rather similar-looking sandpipers.

FEEDING—  A spotted sandpiper is lunging for an insect beneath a rock along the Snake River. Spotted sandpipers forage actively along shorelines, probing the gravel or mud with their bills, lunging at moving prey, grabbing insects off plants, snatching flying insects from the air, all the while constantly and smoothly bobbing their backside. | Photo by Kate Persons

The spotted sandpiper is North America’s most widespread breeding sandpiper. They breed across the continent, from treeline in the north to the southern United States, and from sea level to 14,000 feet in the Rocky Mountains.

They are found near freshwater in many environments, from the margins of urban streams and agricultural ponds to the shorelines of remote rivers and lakes.

On the Seward Peninsula, look for these rump-pumping sandpipers as they forage along the bare gravel shorelines of our streams and their quiet backwaters. Spotted sandpipers are said to be most common in the forested parts of the region, but they are regulars along the streams and water bodies of Nome’s road system.
There are few reported sightings on the northern and western parts of the peninsula.

Like phalaropes, spotted sandpipers are one of a few bird species with reversed gender roles. Females take the lead in courtship and may have more than one mate (polyandry), while males are the primary caregivers for the young. Males have higher levels of prolactin, a hormone that stimulates parental care.

Females are larger and more aggressive than males and arrive on the breeding ground first in spring to establish and defend breeding territories.

Ideal territories include a shoreline for foraging, a partially open area for nesting and some dense vegetation for shade and sheltering chicks. The female stakes her claim with aerial and ground displays to attract males.

Polyandrous females defend large territories and several males may set up their own smaller territories within it, which they defend from each other.

In some places spotted sandpiper pairs are monogamous for the season, in which case the female plays a parental role. But many females have more than one mate, sometimes up to four, each of which raises a brood of her chicks, largely on his own.

It is unknown if spotted sandpipers in this area are generally monogamous or polyandrous.
In 1989, Kessel, in “Birds of the Seward Peninsula, Alaska”, speculated that monogamy was likely most prevalent here due to the low population density at the time.

Nest building is part of the spotted sandpiper’s courtship ritual. The pair may begin, but not complete, several nests while bonding. The actual nest is built after courtship and is often begun by the female and finished by the male.
Nests are a depression scraped in gravel or sand, usually near a shoreline, and lined with small bits of plant material. They are often in the open, or may be partially hidden by a rock, shrub or debris.

Usually, four eggs are laid, a day apart.

The male does most of the incubation. Monogamous females incubate a little, but polyandrous females may leave the first mate as soon as she finds another male in her territory.

Incubation lasts 20 days and the downy, mobile chicks leave the nest almost immediately. Within thirty minutes of hatching, they have already begun their species’ distinctive up-and-down tail bobbing when walking or standing. Most sandpiper chicks are hard to identify without a parent nearby, but the teetering makes the identity of even tiny spotted sandpiper chicks immediately obvious.

The male, primarily, cares for the brood, leading them to good feeding areas and defending them until they fledge when 13 to 16 days old. The young stay near the nesting site for the rest of summer.

JUVENILE— A juvenile spotted sandpiper is feeding along the edge of the Niukluk River. You can see natal down on the young bird’s face and neck where the juvenile plumage had not yet grown in. Remnants of down are hanging from the tips of some newly grown feathers. The breast of a juvenile is all white, as it is on adults in nonbreeding plumage. | Photo by Kate Persons

Spotted sandpipers are opportunistic in their diet and eat a wide variety of terrestrial and aquatic invertebrates, small fish and will peck at dead fish.

They forage actively along shorelines in a meandering manner, probing the gravel or mud with their bills, lunging at moving prey, grabbing insects off plants, snatching flying insects from the air, all the while constantly and smoothly bobbing their backside.

Spotted sandpipers fly low over the water’s surface in a blur of very rapid, shallow wing beats and glides. They are able to make shallow dives and swim briefly underwater to avoid predators.

By early August fall migration has begun, with adult females leaving the breeding grounds first.

By the end of August most spotted sandpipers have left the Seward Peninsula. Unlike many shorebirds that migrate in large flocks, spotted sandpipers migrate alone or in small groups.

A few spotted sandpipers winter as far north as southern coastal Alaska, but most winter from southwestern British Columbia to mid-South America.
One might wonder what the purpose could be of a behavior such as tail-bobbing that draws attention to a small bird. Research suggests the movement signals to predators that the bird is quick, alert and aware, and that pursuit would be a waste of energy. Birds and wildlife have such interesting and varied adaptations to aid in their continued survival.