Seabird’s cry: repertoire and vocal expression of contextual valence in the little auk (Alle alle)

Abstract

Many seabird species breed in colonies counting up to hundreds of thousands of individuals. Life in such crowded colonies might require special coding–decoding systems to reliably convey information through acoustic cues. This can include, for example, developing complex vocal repertoires and adjusting the properties of their vocal signals to communicate behavioural contexts, and thus regulate social interactions with their conspecifics. We studied vocalisations produced by the little auk (Alle alle)—a highly vocal, colonial seabird—over mating and incubation periods on the SW coast of Svalbard. Using passive acoustic recordings registered in a breeding colony, we extracted eight vocalisation types: single call, clucking, classic call, low trill, short call, short-trill, terror, and handling vocalisation. Calls were grouped by production context (based on the typically associated behaviour), to which a valence (positive vs negative) was later attributed, when possible, according to fitness threats, i.e. predator or human presence (negative) and promoters, i.e. interaction with a partner (positive). The effect of the putative valence on eight selected frequency and duration variables was then investigated. The putative contextual valence significantly affected the acoustic properties of the calls. Calls assigned positive valence had higher fundamental frequency and spectral centre of gravity as well as shorter sound duration than these assigned negative valence. These results indicate that the little auk’s vocal communication system may facilitate expression of complex behavioural contexts, and seems to include vocal plasticity within vocalisation types—however, more data are necessary to better understand this effect and possible interplays of other factors.

Long distance calls: negligible information loss of seabird social vocalisations over propagation down to the hearing threshold

“…The most complex call of the little auk repertoire, the classic call, is a long, compound signal with apparent formants, composed of a series of three types of syllables (Fig. 1; Osiecka et al 2023a). It is a social call produced in a range of contexts, both by animals sitting inside their rocky nest chambers, and in flight, e.g.…”

“…2022). Little auks are also very vocally active (Osiecka et al . 2023a), and their calls can carry a richness of static (Kidawa et al .…”

“…The most complex call of the little auk repertoire, the classic call, is a long, compound signal with apparent formants, composed of a series of three types of syllables (Fig. 1; Osiecka et al . 2023a).…”

“…It is a social call produced in a range of contexts, both by animals sitting inside their rocky nest chambers, and in flight, e.g. by birds returning to the colony from the foraging grounds (Osiecka et al . 2023a).…”

“…Another social call emitted in a range of situations, and both inside the nest and in flight, is the single call; a brief, one-syllable vocalisation (Fig. 2; Osiecka et al . 2023a).…”