Behavior

Much of the comfort behavior of the Black-headed Duck is similar to that of other ducks (McKinney 1965). "Nervous birds sometimes head-pumped, gave head-flicks (terminology from McKinney, 1965), head-shakes, or the both-wings-stretch, but these movements did not seem sufficiently regular to be considered part of the preflight behavior" (Weller 1968: 172). "Extreme wing-up, tail-up posture" is an apparent escape reaction.

No information. Egg laying ends by December.

Little information; see Weller (1968) for description of behaviors. In Argentina, pairs observed from mid-September-early December; courtship behavior includes a "Toad-call" with head-pumping followed by a wing-up, tail-up display.
Toad-call: male inflates neck and cheeks, neck down, bill raised at intervals and low quah quah given.
Toad-posture: apparently threat display by males in group; head held low, throat inflated and feathers of head, cheeks and neck erected.
Toad-posture followed by tail-up, tail-wag and then wing-up, tail-up displaying secondaries and scapulars as male lowers head, then head raised with bill pointed upward and wings lifted more extremely; head is then pumped, wings lowered and tail waged in synchrony with wing movements; this whole sequence in about 1 s.
Threat: similar to other ducks.

Most molting groups in February and March are of 10-15 indviduals (Weller 1968). In non-breeding interspecific encounters, Black-headed Ducks are dominated by "all species of grebes, coots, and ducks, except the Versicolor [Silver] Teal (Anas versicolor)" (Weller 1968: 173). No interspecific aggression noted with Cinnamon Teal (Anas cyanoptera); male Cinnamon Teal seen courting an immature Black-headed Duck (Weller 1968).

No information.