sentences:  There is no colour distinction among sexes.The subspecies "A. i. hypoxanthus" is much yellower below than the nominate subspecies.The sombre greenbul is a vocal species, and the most typical call is a monotonous, ringing phrase starting with a penetrating single whistle "weeeewee", followed by a jumbled chortle and ending off with a rather plaintive, drawn out whistle "willy".