The Spectrographic Analysis of Sound Signals of the Domestic Fowl

A spectrographic analysis was made of the following sound signals of the domestic fowl: (a) sounds made by chicks, including distress calls, pleasure notes and fear trills; (b) sounds made by broody hens that serve to attract chicks, including clucking, food calls, and the roosting call; and, (c) warning signals, including the alarm call for aerial predators, the alarm call for ground predators, the alerting call of a broody hen, fear squawks of a hen held in the hand, threat sounds of cocks, and crowing of a rooster. Distress notes of chicks are composed of descending frequencies only, whereas ascending frequencies are the prominent component of pleasure notes. The spectrographic analysis revealed the following common elements in sounds that attract chicks: (i) repetitiveness or segmentation, (2) brief duration of the component notes, and (3) the presence of relatively low frequencies. Warning signals as a group have in common features that are the opposite: (1) relatively long duration. (2) relatively little segmentation or repetitiveness, and (3) absence of very low frequencies. Experimental tests with artificial sounds confirmed these conclusions.