While the diversity and abundance of most taxonomic groups declines as one moves north, the sandpiper family is a dramatic exception. Of the 24 species of sandpipers, nearly all have their breeding groups substantially or entirely in the Arctic.  Of the estimated 19 million birds in this family, 94% breads in Arctic.

An analysis of the species richness of Calidrid sandpipers (the eighteen species of sandpipers in the genus Calidris, plus two closely-related species, the spoon-billed sandpiper and the stilt sandpiper) shows an area of high diversity in the Bering Sea region, reaching a peak in easternmost Chukotka where 11 species are found. By contrast, the area from 80° W (west of Baffin Island) eastwards to 80°E (east of the Yenisei River) has no area with more than four species of calidrids. This phenomenon has been found for other taxa, for example geese, but has not been fully explained.

The area with more than three species coincides precisely with the area defined as Arctic according to botanical criteria. The boundary oh this area is approximately the treeline, which appears to be the southern boundary in summer for most breeding sandpipers. In addition, the area of highest diversity is the area containing the highest number of rare plant species, a connection that requires more examination.

Sandpipers flock to the Arctic in summer for the innumerable insects an the tundra, which provide an ideal food source for rearing young, and which are always available in the perpetual daylight. In winter, sandpipers head south, reaching virtually all the world’s wetlands on their migration and in their winter habitats. Despite the attractions of the Arctic, breeding conditions can still be harsh, and sandpipers have evolved special breeding strategies.

One strategy particularly common among Arctic sandpipers, including the dotterel, sanderling, and the phalaropes, is that the males care for the young. The female dotterel and phalarope has more colorful plumage. After laying her eggs, she may breed again with a different male, producing two or more clutches of eggs in a good summer.  For more other sandpiper species, such as the curlew sandpiper, the female provides most of the care for the hatchlings, whereas the broad-billed sandpiper evolved an intermediate strategy, under which the female incubates the eggs but departs once the eggs have hatched.  These strategies appear to be closely linked with migration patterns. Small changes in these conditions, either inside or outside the Arctic, could have a dramatic effect on sandpiper populations by throwing their migratory and breeding patterns out of balance. Conservation efforts need to consider the entire flyway and the breeding habits of sandpipers.

A final observation about sandpipers is that many Arctic wading birds, as well as some species of their bird families, have brownish-red coloration, especially on the breast and neck. Why this is so is not clear, though the color is always the same shade. Perhaps it is camouflage for birds sitting on the nest on the summer tundra, where low angled sunlight gives a russet hue to many objects.