Temporal and Spectral Analyses Reveal Individual Variation in a Non‐Vocal Acoustic Display: The Drumming Display of the Ruffed Grouse (Bonasa umbellus, L.)

Abstract

Individual variation in vocalizations is a common feature of many forms of long‐distance communication in vertebrates. The extent to which individual variation occurs in non‐vocal, long‐distance acoustic communication has not, however, been tested. Here, we examine the spectral and temporal characteristics of a non‐vocal acoustic signal, the wing‐beating drumming display of the male Ruffed Grouse (Bonasa umbellus, L.), and test whether its structure varies more among individuals than within them. Drumming displays were recorded over two field seasons, and we measured several temporal and spectral features of these recordings. Each drumming display consists of 39–50 pulses produced over a period of 9–10 s with most of the energy concentrated at frequencies below 100 Hz. We calculated the potential for individual coding of several temporal and spectral features, and both the number of pulses and pulse rate were highly individually specific. This was corroborated by analyses of variance, bivariate plots of pulse number and rate, and discriminant function analyses. Overall, we conclude that male Ruffed Grouse produce individually specific drumming displays in a similar fashion to vocal individuality in other birds. The extent to which these individual differences persist from one season to the next is unclear, but individual differences in the number of pulses and pulse rate could provide information on individual identity to conspecifics.

Is it possible to acoustically identify individuals within a population?

“…4 Distribution of the distances moved by male Corncrakes in the Nurzec River Valley in 2012. When pairs of calls showed a similarity value of greater than 0.98 (Pearson's R), they were considered to come from the same individual estimate of similarity, which is lacking in most studies (e.g., Grava et al 2008;Garcia et al 2012), can be used to discriminate between individuals: two calls with a similarity value of less than 0.90 can be considered to belong to different individuals. Simply put, the features of calls recorded in the same place can reveal whether or not those calls were produced by the same individual.…”

“…Despite the many advantages that the use of vocal individuality may present in monitoring and conservation efforts, previous studies have largely focused on the theoretical use of vocal individuality (Terry and McGregor 2002;Klenova et al 2008); it has only sporadically been used as a biometric marker (e.g., Hoodless et al 2008;Mikkelsen et al 2013). Moreover, most studies have examined fewer than 30 individuals and have not considered the possibility that two individuals might be acoustically indistinguishable (Rebbeck et al 2001;Garcia et al 2012). Because signal coding possibilities are finite, it becomes more likely to come across two acoustically indistinguishable individuals as sample size increases.…”

A quantitative morphological analysis of the inner ear of galliform birds

“…made by their wings and tail (Takahashi and Hasegawa, 2008), which extend to infrasound (Freeman, 2012). Male ruffed grouse [Bonasa umbellus] rarely vocalize and their courtship consists entirely of a non-vocal signal, whereby they perch on a log and beat their wings rapidly to create a low frequency (<100 Hz) drumming sound (Aubin, 1972;Garcia et al, 2012;Hjorth, 1970). Thus, some galliforms produce low frequency sounds that may have driven the evolution of low frequency specializations in their auditory system.…”

“…1). Male Indian peafowl [Pavo cristatus] also have a range of vocalizations as well as sounds Ornithology (1999) and the drumming of the ruffed grouse was recorded in Western Alberta (Garcia et al, 2012). made by their wings and tail (Takahashi and Hasegawa, 2008), which extend to infrasound (Freeman, 2012).…”

Seasonal Variation in Forebrain Region Sizes in Male Ruffed Grouse <b><i>(Bonasa umbellus)</i></b>

“…Drumming is typically performed atop a platform (e.g. a fallen tree, stump or stone) from a stationary position and consists of 40-50 wingbeat movements performed over 8-11 s, which produces a low-frequency sound [Garcia et al, 2012]. Other grouse species use wingbeats and 'flutter jumps' for courtship, but always in conjunction with vocalizations [Hjorth, 1970;Johnsgard, 1983].…”