Contextual variations in calls of two nonoscine birds: the blue petrel <i>Halobaena caerulea</i> and the Antarctic prion <i>Pachyptila desolata</i>

Abstract Bird vocalizations are critical cues in social interactions as they convey temporary information varying with the context, for example, signaler motivation when facing a rival or potential mate. To date, literature mainly focused on learning birds. Burrowing petrels (Procellariidae) nonlearning birds limited vocal repertoire. Bachelor males communicate conspecifics single call emitted three situations: absence of certain auditory (spontaneous calls), toward females (female-directed and (male-directed calls). We first hypothesized that, although structure is preserved, temporal spectral parameters vary between types bachelor males, translating different motivations (Motivation Hypothesis). go further, we that acoustic variations male-directed calls indicate signaler’s aggressive and, therefore, similar whether produced by breeder (Breeding Status tested two hypotheses performing field playback experiments petrel species: blue (Halobaena caerulea) Antarctic prion (Pachyptila desolata). Despite obvious stereotypy, observed frequency shifts react to female male, which may translate sexual signaler. Furthermore, similarity both suggests motivation. So far, plasticity has been greatly underestimated. Here, highlighted expression through ability produce species genetically coded vocalizations.