The red-knobbed coot is an omnivore, and will take a variety of small live prey including the eggs of other water birds. Its main food in most waters however comprises various waterweeds such as species of Potamogeton for which it commonly dives.
This is a noisy bird during mating, but its vocalisations are quite different from the Eurasian coot. It gives a fast kerrre like the little crake, a harsh ka-haa and a grunting hoot "oot oot" that suggests that the name "coot" might be onomatopoeia, but inspection of the etymology of "coot" fairly decisively negates any such suggestion.
The habits of the red-knobbed coot are practically identical to those of the Eurasian coot. It is much less secretive than most of the rail family. Where it is undisturbed it is likely to bully any intruder, even large birds such as Egyptian geese, if they do not defy its challenges. It can be seen swimming on open water or walking across waterside grasslands. It is an aggressive species, and strongly territorial during the breeding season.
The red-knobbed coot is reluctant to fly and when taking off runs across the water surface with much splashing. It does the same, but without actually flying, when travelling a short distance at speed (to escape a rival, for example, or to dispute possession of a choice morsel). It bobs its head as it swims, and makes short dives from a little jump.
