Least Sandpipers - Our tiniest shorebird

Least sandpipers might be tiny, but they are spunky, spirited sprites worth getting to know.
Barely larger than a sparrow and weighing only about an ounce, the least is North America’s smallest sandpiper and they are as little as any shorebird in the world.
Seen next to our more common, small sandpipers—the western and semipalmated sandpipers—the least’s smaller size is noticeable. When seen alone, its distinctive yellow-green legs, though they could be mud-stained, will set it apart from its similar-looking black-legged relatives.
These tiny shorebirds are long distance migrants that travel thousands of miles between breeding grounds in the far north and wintering areas as far south as Chile and Brazil in South America.
In fall, some eastern populations of leasts make nonstop 1,800-to-2,500-mile flights over the Atlantic Ocean between New England and northeastern South America. Western populations such as ours move in shorter hops, migrating through interior North America to the gulf coast or Central America, or along the Pacific Coast to South America. Spring migration for all populations is through North America.
Least sandpipers breed in subarctic tundra and northern boreal forests across northern North America. Coastal wetlands, sedge meadows, grassy bogs and tussock-heath tundra are favorite nesting habitats.
In her 1989 publication Birds of the Seward Peninsula, Alaska, ornithologist Brina Kessel reported that least sandpipers were regular breeders at Koyuk, and that the Niukluk and Fox River drainages were at the western edge of their breeding range on the Seward Peninsula. Further west, their occurrence was described as erratic.
Since that time, eBird reports have documented the species’ expansion and increasing numbers as far west as Brevig Mission. They are regular breeders now in the Nome area and there are many sightings of these birds and reports of nesting activity along the Kougarok and Teller Roads to the north and west.
I have been greeted by the high-pitched, repetitive alarm calls of nesting pairs broadcasting from stunted willow tops near a favorite campsite at Mosquito Pass. 
In spring, males arrive as early as the second week of May, about a week before the females. They establish and defend a nesting area, often returning to the same site each year. Males call noisily while circling over their territory with alternating bursts of rapid wingbeats and glides, followed by a dive to the ground. These vocalizations and aerial displays also attract females when they arrive.
Until pairs are formed, neighboring males can be cantankerous, chasing and fighting each other, sparring with their feet, or sometimes landing on each other’s backs and pulling feathers on each other’s heads—quite a show.   
The male also prepares several nests or “scrapes,” pressing his body into the grassy ground and rotating to create a shallow depression. The female, sometimes a previous mate, checks them out and takes her pick, adding a scant lining of vegetation to her scrape of choice.
The pair shares incubation of their three to four eggs, but the male spends more time on the nest than his mate.
You know you are near a nest when one parent bursts excitedly into noisy, hovering flight overhead, while the other feigns injury and desperately attempts to lead you away with a “rodent run” over the ground. Or the little bird may approach you quite closely and stand bravely on the ground nearby, trilling a defiant warning to trespass no further.
In 19 to 23 days the eggs hatch and down-covered chicks emerge, ready to leave the nest in a day. The chicks feed themselves, while the parents, or eventually just the male, guides and guards them until they fledge in about 15 days.
When a threat is lurking, the adults sound a continuous trilling alarm while flying overhead or perched on a nearby shrub or hummock. The well-camouflaged chicks respond by hunkering motionless until the threat has passed and the alarm calls cease. 
As ground-nesting birds, the eggs and young are especially vulnerable to predators, including ravens, gulls, sandhill cranes, jaegers, short-eared owls, foxes and dogs.
As is the case for many shorebird species, the female is depleted by producing large eggs containing such well-developed young. The female least sandpiper abandons the family within a week and moves to rich feeding areas to rebuild her reserves for migration.
Least sandpipers eat a variety of terrestrial and aquatic invertebrates such as insects and small crustaceans. Sometimes seeds of marsh grasses are on their menu.
They forage on the edges of wetlands or mudflats, feeding on slightly higher and drier ground than other shorebirds, and they select smaller prey, thus minimizing competition. Female least sandpipers have slightly longer bills than males and can reach deeper into the mud for larger prey, again reducing competition.
Watch for these tiny shorebirds foraging with a distinctive hunched posture as they walk slowly, pecking at the surface, or probing shallowly in the mud with short, narrow bills for small invertebrates.
Researchers studying least sandpipers discovered a feeding technique used by many shorebirds—surface tension transport. When they locate prey with their bills while probing wet mud, surface tension of the water quickly transports prey from the tip of the bill into their mouth.
Least sandpipers are a common but declining shorebird. The destruction and degradation of wetlands, especially along migratory routes and wintering grounds are a major concern for this species and many other shorebirds.
Fall migration is underway and will continue through August. Look for these tiny, yellow-legged sandpipers amongst flocks of western and semipalmated sandpipers and dunlin. Away from the breeding grounds, least sandpipers can be quite tolerant of people. If you are patient and respectful they will sometimes allow you to approach closely to watch and photograph them.

Listen here to the Least sandpiper flight song recorded in Nome by Maureen Chambrone
https://macaulaylibrary.org/asset/647508132