The Biology of Bird-Song Dialects

Abstract

No single theory so far proposed gives a wholly satisfactory account of the origin and maintenance of bird-song dialects. This failure is the consequence of a weak comparative literature that precludes careful comparisons among species or studies, and of the complexity of the issues involved. Complexity arises because dialects seem to bear upon a wide range of features in the life history of bird species. We give an account of the principal issues in bird-song dialects: evolution of vocal learning, experimental findings on song ontogeny, dialect descriptions, female and male reactions to differences in dialect, and population genetics and dispersal.We present a synthetic theory of the origin and maintenance of song dialects, one that accommodates most of the different systems reported in the literature. The few data available suggest that large, regional dialect populations are genetically differentiated; this pattern is correlated with reduced dispersal between dialects, assortative mating by females, and male-male exclusion. At the same time, “subdialects” may be formed within regional dialects. Subdialect clusters are usually small and may represent vocal mimicry among a few adjacent territorial males. The relative importance of genetic and social adaptation may contribute to the emergence of subdialects; their distinctiveness may be correlated with the degree of polygyny, for example. Thus, subdialect formation is linked to one theory of the evolution of repertoire size, but data are too fragmentary to examine this idea critically.

Bird song, ecology and speciation

“…Kroodsma et al 1984;Baker & Cunningham 1985a). We argue that determining the role of song in speciation is complicated by a dichotomy that exists among studies that focus solely on assortative mating, and others that focus on ecological divergence and habitatdependent selection pressures.…”

On the maintenance of bird song dialects

“…Geographically distinct acoustic clusters yield sharp transitions in vocal parameters across localities and are referred to here as dialects (Marler & Tamura, 1962;Baker & Cunningham, 1985;Slabbekoorn & Smith, 2002;Podos & Warren, 2007). The best studied dialectal bird species is the white-crowned sparrow (Zonotrichia leucophrys) for which there is ample field data on different subspecies (e.g., Baptista & King 1980;Baker & Cunningham 1985;Cunningham et al 1989;Nelson et al 2004).…”

“…The best studied dialectal bird species is the white-crowned sparrow (Zonotrichia leucophrys) for which there is ample field data on different subspecies (e.g., Baptista & King 1980;Baker & Cunningham 1985;Cunningham et al 1989;Nelson et al 2004). Studies on this species have provided insight into dialect persistence (e.g., Harbison et al 1999;Nelson et al 2004), as well as dialect-dependent response behaviour from playbacks in the field (e.g., Nelson et al 2004;Derryberry 2011), and dialect-dependent local adaptation (MacDougall-Shackleton et al, 2002;Luther & Baptista, 2010).…”

Using Shannon Entropy on Measuring the Individual Variability in the Rufous-bellied Thrush Turdus rufiventris Vocal Communication

“…Like the majority of Oscines that have songs with populational or even individual variations (Mundinger, 1982;Marler, 1997;Kroodsma, 1982Kroodsma, , 1996Canady et al, 1984;Baker & Cunningham, 1985;Todt & Hultsch, 1996), thrushes show inter-and intra-individual variations. Those variations represent indirect evidences of a learning process during song ontogenesis (Vielliard, 1987).…”