Vocal individuality in drumming in great spotted woodpecker—A biological perspective and implications for conservation

Abstract

Animals—including conservation biologists—use acoustic signals to recognise and track individuals. The majority of research on this phenomenon has focused on sounds generated by vocal organs (e.g., larynx or syrinx). However, animals also produce sounds using other parts of the body, such as the wings, tail, legs, or bill. In this study we focused on non-syrinx vocalisation of the great spotted woodpecker, called drumming. Drumming consists of strokes of a bill on a tree in short, repeated series, and is performed by both males and females to attract mates and deter rivals. Here, we considered whether the great spotted woodpecker’s drumming patterns are sex-specific and whether they enable individual identification. We recorded drumming of 41 great spotted woodpeckers (26 males, 9 females, 6 unsexed). An automatic method was used to measure the intervals between succeeding strokes and to count strokes within a drumming roll. The temporal parameters of drumming that were analysed here had lower within- than between-individual coefficients of variation. Discriminant function analyses correctly assigned 70–88% of rolls to the originating individual, but this depended on whether all individuals were analysed together or split into males and females. We found slight, but significant, differences between males and females in the length of intervals between strokes—males drummed faster than females—but no difference in the number of strokes within a roll. Our study revealed that temporal patterns of drumming in the great spotted woodpecker cannot be used for unambiguous sex determination. Instead, discrimination among individuals may be possible based on the intervals between strokes and the number of strokes within a roll. Therefore, it is possible that differences in the temporal parameters of drumming may be used by birds to identify each other, as well as by researchers to aid in census and monitoring tasks.

Hey mister Tambourine Dove, sing a song for me: simple but individually specific songs of Turtur tympanistria from Cameroon

“…The initial DFA was built with simple variables which could be measured for the whole songs (duration, number of syllables, frequency of song etc.). However, after initial screening of songs it was clear that they differ in number of notes and in order to compare characteristics based on note measurements we had to limit analyses to notes common for all cases (similarly as did Budka et al 2018 for strokes in study on Great Spotted Woodpecker Dendrocopos major drumming). In the studied population we found songs containing between 12 and 59 notes.…”

Chest beats as an honest signal of body size in male mountain gorillas (Gorilla beringei beringei)

“…Interestingly, we found smaller within-individual than between-individual coefficients of variation, particularly for chest beat duration and number of beats (39.0 vs. 85% and 31.6 vs. 67.9%, respectively). Notably, several temporal aspects of non-vocal drumming displays by chimpanzees ( Pan troglodytes ), ruffed grouse ( Bonasa umbellus ) and great spotted woodpeckers ( Dendrocopos major ) show significant individual variation, similar to many vocalizations in a wide range of species 19 , 51 , 52 . For example, the buttress drumming of individual chimpanzees significantly differ in the mean duration and the mean number of beats 52 , 53 .…”

Hissing of geese: caller identity encoded in a non-vocal acoustic signal

“…This represents most studied systems, but sounds of terrestrial vertebrates are not only produced in the larynx or syrinx. Several avian species are known to produce non-syrinx sounds, which can be produced by instrumental feathers (Murray, Zeil & Magrath, 2017), beak drumming (Budka et al, 2018;Dodenhoff, Stark & Johnson, 2001), wings beating (Garcia et al, 2012;O'Neil, Charrier & Iwaniuk, 2018), the rattling of mandibles (Eda-Fujiwara et al, 2004), step dances (Ota, Gahr & Soma, 2017) or else, by using tools (Heinsohn et al, 2017).…”

“…Besides these emissions, sounds can be produced by constriction, anywhere along the pathway from the lungs to the lips or nostrils (in mammals), or to the bill (in birds), resulting in turbulent, aerodynamic sounds (Fitch & Hauser, 2002). As of late, non-vocal, or unvoiced, signals have surprisingly received very little attention in comparison to other acoustic signals (Budka et al, 2018;Stomp et al, 2018a). The production mechanism of hissing has been studied in the domestic goose (Brackenbury, 1978).…”

“…Even though individual expressions within the vocalizations of birds have been intensively studied, the majority of studies have been devoted to the sounds produced by the syrinx. Such studies of non-syrinx vocalizations remain scarce, with little being known about their sound production mechanisms or their biological functions, including within and between-individual variation (Budka et al, 2018). The extent to which an individual's variation occurs in turbulent sound like hissing has not, however, been tested.…”