The relationship between latitude, migration and the evolution of bird song complexity

Abstract

For the past several decades it has been proposed that birds show latitudinal variation in song complexity. How universal this variation may be and what factors generate it, however, are still largely unknown. Furthermore, while migration is confounded with latitude, migratory behaviour alone may also be associated with variation in song complexity. In this paper we review the literature to assess current ideas on how latitude and migratory behaviour may drive large-scale geographical patterns of song complexity. At least seven distinct hypotheses have been proposed in 29 studies of the topic. Four of these hypotheses posit that sexual selection pressures co-vary with latitude and/or migration, resulting in concordant changes in song. Other hypotheses suggest that mechanisms other than sexual selection, such as large-scale changes in environmental sound transmission properties, may be at play. Sixteen studies found support for increased song complexity with increased latitude and/or migration, whereas 13 did not. Relatively few studies exist on this topic, and methodological differences between them and variable definitions of 'complexity' make it difficult to determine whether results are comparable and concordant. At a minimum, it is possible to conclude there is no strong evidence that song complexity increases with latitude and/or migration in all birds. Future work should focus on examining multiple hypotheses at once to further advance our understanding of how latitude, migration and song complexity may or may not be related.

Sex role similarity and sexual selection predict male and female song elaboration and dimorphism in fairy‐wrens

“…However, support for an association between latitude and song complexity is mixed. About half of the studies on this topic find no support for this or even the opposite pattern (reviewed in Najar & Benedict, 2019 ). Variation in these findings could be due to which song metrics are compared within each of these studies (Benedict & Najar, 2019 ) to different evolutionary pressures acting on different aspects of song structure (e.g., sexual selective pressures vs. morphological constraints; Cardoso & Hu, 2011 ; Derryberry et al, 2012 ; Greig et al, 2013 ), or to a lack of association between latitude and the expected life‐history traits in the species examined.…”

Song Richness Index: A measure to understand the diversity and repetition of notes in a birdsong

“…The copyright holder for this preprint this version posted December 18, 2021. ; https://doi.org/10.1101/2021.12.18.472638 doi: bioRxiv preprint (Spencer et al 2003;Sawant et al 2021;L. Z. Garamszegi, Balsby, and Bell 2005;Najar and Benedict 2019). These measures of immediate diversity have shown promising results in understanding the diversity across multiple fields of biology.…”

“…The immediate diversity of the notes in birdsongs is often studied using some of the conventional measures-Shannon’s Diversity (Kershenbaum 2014; Sasahara et al 2015; Silva et al 2000), Simpson’s Diversity (Simpson 1949; Magnussen and Boyle 1995), and the types of notes within a song or Note Diversity (Spencer et al 2003; Sawant et al 2021; L. Z. Garamszegi, Balsby, and Bell 2005; Najar and Benedict 2019).…”

Evidence of a trophic niche shift in an omnivorous migratory bird in South America: A comparison of stable isotope signatures in feathers between migratory and sedentary subspecies of Tyrannus savana

“…1 and 2). Such a comparative framework has been successfully employed to test hypotheses that explain differences between migratory and nonmigratory (sedentary) bird taxa in their coloration (Fitzpatrick et al, 2004), vocal complexity (Najar & Benedict, 2019;Nelson, Marler, & Morton, 1996), breeding phenology (Kimmitt, Sinkiewicz, & Ketterson, 2020), and fitness (Buchan, Gilroy, Catry, & Franco, 2020), as well as a history of linking morphology with diet or foraging guild (Tellería, Blázquez, De La Hera, & Pérez-Tris, 2013;Neto et al, 2013).…”