The Sungrebe is most frequently seen swimming half-submerged along the surface of water somewhat like Anhingas (Anhinga anhinga), often close to the shore. They swim with exaggerated back and forth movements of the head and neck, probably in rhythm with each propulsive foot stroke. Food usually is gleaned from vegetation overhanging the water (Stiles and Skutch 1989).
The Sungrebe often has the reputation of being shy and wary. If disturbed, it usually swims towards cover, or takes flight. Diving is infrequent.
During the middle of the day, Sungrebes may rest perched on a branch just above the water. At dusk, individuals climb (rather than flying) to a higher concealed roosting place in thick vegetation.
In southern Mexico, male Sungrebes hold a year-round territory. The territory extends for about 200 m along the bank of a stream; the male actively defends this are from intruding birds. Territorial disputes are reported to increase during the spring breeding season (Alvarez del Toro 1971).
In Sungrebe courtship, the male and female swim in counter circles with their necks stretched out low over the water and their wings half-raised. Their circles steadily decrease in size and copulation takes place when the two birds meet (Alvarez del Toro 1971).
Social and interspecific behavior
Sungrebes are mostly solitary (Alvarez del Toro 1971).
It is presumed that swimming birds serve as prey to birds of prey, while roosting birds may be at risk from terrestrial predators (Alvarez del Toro 1971).