Pishing is used most effectively in the Holarctic, where it is thought to work due to its similarity to the scold calls of tits and chickadees (birds in the family Paridae).
These scold calls, a form of mobbing behaviour, attract other birds which come in to establish the nature of the potential threat.
Apart from the mobbing call hypothesis, it has also been suggested that pishing may be treated as an invitation to join a "mixed-species foraging flock" and birds do not themselves vocalize or show aggressive behaviour.
The same study noted that pishing did not work in the old-world tropics and suggested that it may be due to the lower densities of migrants.
Some birders in Australia use a variant of pishing called "squeaking" (making a kissing sound through pursed lips or against the back of one's hand) to which white-eared honeyeaters, several species of whistlers and grey fantails show an initial response and in turn attract other species.