There's only one way to describe calling Channel-bills - raucous. Sample B04 is a fairly close-up (20 metres) recording of two birds, either a pair courting, or two birds acting aggressively which were flying around overhead, then off into the distance which is where most people hear them from because they can be heard from half a kilometre away. In the middle of this sample the two birds appear to be singing alternately, like an antiphonal duet - or maybe they were just trying to shout one another down! It is difficult to assign any particular Channel-bill call to a particular behaviour. When lone birds call, usually around daybreak, they repeat a single high-pitched "quorrk", usually in flight and to my ear, this is the closest approach there is to an advertising call. The harsh, rapidly repeated Kaa-kaa-kaa-kaa in sample LS10023 was made by a bird that was feeding in a fig tree - there were other birds present. It sounds a bit stirred up but the exact function of the call is not clear. I've seen a tree full of Channel-bills feeding for quite some time without making a sound. Note that this call also occurred in sample B04 leading up to the loud courtship? calls. In sample 177-580 I recorded the pleading calls of the two young Channel-bills in pic.#348201 to their Pied Currawong foster parent.