The Black-bellied Whistling-Duck is found in flocks taking residence around small ponds and lakes. At dusk, they usually flock to the air, making circular trajectories and a lot of noise, and finally descending again into their watery home. Their calls are very high pitched and loud. Their necks are very flexible, so when resting, they normally turn their heads back and tuck they into the middle of their wings; they also like to stand up in one foot, with the other one hidden inside their belly feathers.. Their bills are characteristically pink, as well as their legs. Juveniles are duller and have brownish bills instead.