Red-necked phalaropes reverse the role of the sexes in their behaviour as well as their plumage. The females are the first to arrive at the summer breeding sites, usually around the end of May, and will compete to secure the best nesting position. When the males arrive, the female will make her selection and, from then on, defend him against other females for as long as her eggs are being incubated. Once the chicks have hatched, the female deserts the male, and he alone will rear the young phalaropes. If there are enough male birds, females may mate with several, and even attempt to rear a second brood of chicks within the short Arctic (or sub-Arctic) breeding season. The pair bond between the birds is short-lived, however, and usually ends once the eggs hatch. The clutch consists of four eggs as a rule, laid in a nest with a grass lining built by both birds into a grass tussock. The eggs are oval in shape with one end sharply pointed, and are brown with dark-brown blotches, which serves to camouflage them against predators. After an incubation period of 18 to 20 days, the chicks emerge well developed and are able to leave the nest as soon as their down dries to follow their father to good feeding areas.
Phalaropes feed in a way that is unique amongst waders. They swim rapidly round in circles, picking off insects and other water-living creatures as they appear on the surface of the pool. For this purpose, their feet are only partially webbed or ‘semi-palmated’.