A birder can coax birds out from the cover of trees and undergrowth to investigate the pishing noise. Some birders just say the word “pish, pish, pish.” Others use a shushing style. One characteristic that seems to work is a prolonged, unhurried and even-toned quality in the sound. Loudness is not important and can be counterproductive. Also it’s better if each note is drawn-out and raspy. The sound must arouse a bird's natural inquisitive instinct enough to investigate the incessant, repetitive calling.
For beginners, pishing works best in an area with thick vegetation. Once you’re deep in the woods, you are literally inside the birds' living room, and pishing produces the best views and detects the most species. Another tip is to stay perfectly still. Bird vision is much sharper than ours and is highly tuned to detect movement. Flocking is a survival aid and ensures that many pairs of eyes and ears are on the alert for danger. Sitting down and remaining stationary makes it harder for the birds to locate a mystery sound.
Once attracted by pishing, the first birds to arrive often announce their presence by calling. In turn this stimulates others to join in the commotion. However once they discover the sound’s source, they quickly melt away as they realize they have been duped.
The exact translation of “pish” is unclear. It might be a “hey, you” and the birds pop out to see if someone was talking to them. The other theory is that it imitates an anxiety call of a bird in trouble or an alarm call of a squirrel. Mobbing behavior is commonplace among little birds that can become prey of owls, hawks, and other predators. So it may be more of a “look out, help me” warning call that gathers an entourage of irate small birds into action to protect themselves. Or it may just be a bit of peoplewatching on the part of the birds. However, the meaning is still unclear so don’t overuse the technique because we don’t want to unnecessarily overstress our bird friends.