Chapter 5 Vocal Performance and Sensorimotor Learning in Songbirds

Female mate choice based upon male motor performance

“…Nowicki et al (1998) hypothesized that one kind of behavioral display, birdsong, should provide a particularly reliable indicator of male quality, because the development of brain nuclei that constitutes song learning occurs when young birds are energetically and nutritionally challenged. Support for this "developmental stress" hypothesis appeared in a number of studies (reviewed by Podos et al 2009). For example, Nowicki et al (2002) showed that swamp sparrows, Melospiza georgiana, partially deprived of food during early life developed smaller brains, smaller song control brain areas and reduced song learning, as compared to control birds.…”

“…A recent review by Byers & Kroodsma (2009), for instance, questions the biological validity of assays used to infer female preferences for large repertoires, and also notes that small repertoires persist in many songbird lineages, with corroborating evidence in the evolution of some clades for repertoire reductions rather than expansions. An alternative set of characteristics to which females may attend more generally, independent of repertoire size, concerns male vocal skill, as reflected, for example, in the production of particular syllables and phrases and in the consistency with which vocal elements are repeated across renditions (Lambrechts, 1996;Gil and Gahr, 2002;Podos et al, 2009). Studies of vocal mechanics during the last 25 years have illustrated that song production by male birds is intrinsically challenging, involving the simultaneous control and coordination of breathing, syrinx modulations (the left and right sides having separate innervations) and vocal tract modulations including those of the trachea, mandible and oropharyngeal cavity (Nowicki, 1987;Podos and Nowicki, 2004;Suthers, 2004;Riede et al, 2006).…”

“…We suggest that there are probably many other aspects of birdsong that represent "Olympian" performances, and in which relevant variation among singers is defined by how closely individuals can approach the physically maximum possible performance. Indeed, the prevalence of sensorimotor song development in birds may be a reflection of the fact that song is physically challenging to produce, and that practice is required to enable accurate model reproduction (Podos et al 2009). …”

Integrating perspectives on vocal performance and consistency

“…Recently, an increasing number of behavioral ecologists have used adult song performance as a metric for male quality (reviewed in Podos et al, 2009). For example, a number of studies illustrate that rapidly producing song elements that span a broad range of frequencies is difficult and that females prefer males that can produce such difficult vocalizations (e.g.…”

Bilateral coordination and the motor basis of female preference for sexual signals in canary song

“…Exactly how song contributes toward achieving these goals remains controversial, despite its relevance to vocal communication and the evolution of song diversity. In some species, females prefer males who exhibit particular song traits such as a large repertoire (but see Byers and Kroodsma, 2009), those who spend the most time singing, or those who sing a local dialect (reviewed by Gil and Gahr, 2002;Grether, 2010;Nowicki and Searcy, 2004;Podos et al, 2004;Podos et al, 2009;Riebel, 2009;Sakata and Vehrencamp, 2012;Vehrencamp, 2000). Models of adaptive sexual selection assume these traits convey information about the sender's genotypic or phenotypic quality, which females can use in selecting a mate.…”