The wide-spread Tit-Witted Cross-Billed Guester has the peculiar behaviour of sneaking into large communal nesting areas developed by other species, and spraying the structures with an acidic mud which it manufacturers in its large, irregular mouth. Because its plumage is mottled in dull streaks and shaded patches, it blends in invisibly before and after its defacements. The original occupants of the communal nest structure often twit about in consternation at first, but gradually just go on building their nesting areas and ignore the obnoxious intruder.
The Guester is related by DNA to the Mud-Slinging Troll-Twit and the Bitching Grebe.