A little Spotted Sandpiper had the entire beach of Vadnais reservoir to itself and moved slowly along the shoreline probing now and then in the mud and under leaves as I stood quietly and watched.
Spotted Sandpipers are likely the most widespread breeding sandpiper in North America, nesting from northern most Alaska to the mid-continental U.S. along rivers, lakes, and streams.
And their breeding system is particularly interesting because they exhibit a sex role reversal compared to most other bird species. Instead of the typical female role of incubation and hatchling care, Spotted Sandpiper females “collect” multiple males, laying a clutch of eggs in each male’s nest, which he will then incubate. After they hatch, the male is in charge of protecting and providing food for the chicks, while the female goes off to find another male to mate with.
Female Spotted Sandpipers arrive first on the breeding ground, establish their territory, and then compete with each other for males to mate with. Since females can store sperm from multiple matings for up to a month, the male may be incubating and tending to chicks that are not his offspring! This breeding strategy, called polyandry, is rare among birds but is found in several shorebird species, in Northern Jacanas, occasionally in Acorn Woodpeckers, and in Harris Hawks.