Pros and cons, dos and don’ts of playback

We recognize that the primary interest many have in bird sound recordings is for use in playback, so that an unseen vocalist can be brought into view or so that a species of interest can be stimulated to vocalize and thus reveal its whereabouts.
Playback can disturb sensitive birds, particularly on their breeding grounds, where it can lead to increased stress levels or even nest desertion. For these reasons it is illegal in some frequently birded places. Please use playback responsibly, if at all! Responsible playback would include avoiding playback of species of threatened status or those that are heavily sought by birders in areas of restricted extent, and avoiding very loud, sustained playback.
Bear in mind that in nature birds are accustomed to dealing with the vocalizations of their neighbors, and that playback is not inherently different, so playback in moderation should not be a problem in most areas and with most species.

Whenever possible, the use of playback of conspecifics is documented for AVoCet recordings in the “playback used?” field, as playback can dramatically influence speed and intensity of vocalization. Ideally, a recording series would be documented to indicate whether a given recording was made before playback started, or how long after playback it was made, etc.
If a response appears to have been made to playback of non-conspecific vocalizations, that would be useful information as well. Observed behavioral responses of the bird to playback may be described more fully in the “Behavior” field. Human imitations or other sounds (pishing, squeaking, owl calls etc.) used to elicit a response are also listed in the “playback used?” field, and described as such.

The extensive use of playback and imitations often causes a problem in sound recording, in that these can easily be confused with actually vocalizing birds.
Most human whistles can be distinguished from the real thing by their different appearance on sonagrams (typically more irregular, lower-pitched, and/or “harder” than the bird they imitate), and most instances of playback can be distinguished especially on sonograms by the sudden increase in background noise, different patterns of e.g. insect noise in the background, and/or repetitiveness of identical strophes; but high-quality playback at low volumes is especially difficult to weed out.
Thus, when playback/imitation is being used this is best noted.