There is reverse sexual dimorphism in phalaropes — females are more brightly colored than males. If you compare the photos, look for the following:
- head coloration is more uniform and darker gray in females; it has a browner tone in males
- the white spot above the eyes is brighter and more distinct in females; it is duller and blends into a supercilium (eyebrow) connected to the red hindneck patch in males
- the red hindneck patch wraps around in front of the neck/breast in females; it's less extensive and more amber-colored in males
For comparison, here's the female:
In phalaropes, sexual roles are also reversed. Male phalaropes provide all parental care. The male incubates the eggs and broods the chicks, while the female rarely visits the nest after the last egg is laid.