Non‐Salient Geographic Variation in Birdsong in a Species That Learns by Improvisation

Abstract

Geographic variation in birdsong and differential responses of territorial males to local and non‐local song variants have been documented in a number of songbird species in which males learn their songs through imitation. Here, we investigated geographic song variation and responses to local and non‐local song in the grasshopper sparrow (Ammodramus savannarum), a species in which males develop song by improvisation rather than imitation, as a first step toward understanding how the extent and salience of geographic song variation is related to the mode of song development. To describe the geographic variation in song, we compared songs from populations in eastern Maryland and central Ohio, USA, using multiple acoustic analysis techniques. We then conducted a playback experiment in Maryland using local and non‐local (Ohio) songs to test how territorial males responded to this geographic variation. We found acoustic differences between songs from the two sites. However, males responded similarly to playback of these songs, suggesting that this geographic variation is not behaviorally salient in a territorial context. Together with previous studies, our results suggest that across species, geographic song variation and the extent to which this variation functions in communication may be correlated with the accuracy with which song models are imitated during song development.

Geographical variation in song phrases differs with their function in white-crowned sparrow song

“…The partially independent distributions of note complex and trill types (Fig. 5) replicates findings from Nuttall's white-crowned sparrow, Z. l. nuttalli (Baker & Thompson 1985;Slabbekoorn et al 2003) and in other species where different song types vary independently in space (Byers 1996;Kroodsma 1996;Beebee 2002;Soha et al 2016). The tendency to improvise note complexes, coupled with male dispersal could found novel song types in new areas, which would then be imitated in subsequent generations.…”

“…Behaviors acquired by social learning such as bird song may provide messages concerning the identity, quality and motivation of the singer (McGregor 1991;Catchpole & Slater 2008). In several species of birds with a repertoire of two or more song types, song types with different messages or functions have different patterns of geographic variation (Byers 1996;Kroodsma 1996;Beebee 2002;Soha et al 2016), and vocalizations with similar functions share patterns of geographic variation (Baker 2011). The inference from these results is that vocalizations with different spatial patterns of variation differ in their mode of vocal development, as has been found in two species, the chestnut-sided warbler (Setophaga pensylvanica, Byers & Kroodsma 1992) and the grasshopper sparrow (Ammodramus savannarum, Soha et al 2009).…”

Vocalisation of the rare and flagship species Pharomachrus mocinno (Aves: Trogonidae): implications for its taxonomy, evolution and conservation

“…Nevertheless, previous playback experiments showed that males of P. mocinno could respond to territorial vocalizations of P. costaricensis as actually did other species of the family Trogonidae responding to the same vocalizations tested (2017 personal communication from S. Solorzano to PB, unreferenced). This failure to discriminate an allospecific song has been reported in other bird species (Nelson 1998;Soha et al 2016) and does not preclude that females could discriminate allospecific territorial and courtship vocalizations in a mate choice context (Seddon and Tobias 2007).…”

Geographic variation in marmots’ alarm calls causes different responses

“…Surprisingly, our tests revealed that receivers perceived acoustic differences and categorized alarm calls as local or non-local calls. Such behavioural consequences imply that these acoustic differences are meaningful for them (Soha et al 2016). Most studies focused on male territorial defence or female attraction in birds and their results are contrasted with stronger response to local songs in some cases, absence of preferences or mixed responses in others (see Becker 1983;Catchpole and Slater 2008).…”