Macrogeographic Variation in Song – a Test of Competition and Habitat Effects in Blue Tits

Abstract

Investigations into the environmental causes of phenotypic variation may reveal information regarding the selective pressures leading to the evolution of these phenotypes. Blue tit (Parus caeruleus) song varies geographically in the proportion of song types that contain a trill (i.e. a series of identical notes repeated in sequence at a very rapid rate produced at the end of a song). In order to determine the environmental factors influencing geographic variation in the proportion of blue tit songs with a trill, we conducted a comparative study. At macrogeographic and regional scales we examined the effect of three factors that could influence geographic variation in blue tit song: dominant vegetation type, intraspecific competition and interspecific competition with great tits (Parus major). Interspecific competition may result in song convergence or song divergence (hereafter called character shift). The results we obtained are consistent with predictions of the character shift hypothesis: the proportion of songs presenting a different syntax to great tit songs (songs with a trill) increases significantly with relative great tit density. Results do not support predictions of hypotheses concerning song convergence or intraspecific competition. The results are consistent with some of the predictions of the acoustic adaptation hypothesis.

Community convergence in bird song

“…There are examples in the literature of acoustic competition among species either causing character shift (Wallin 1986;Doutrelant and Lambrechts 2001;Seddon 2005; see also Kirschel et al 2009, for an example with a non-passerine bird) or limiting song variation (Kroodsma 1985;Naugler and Ratcliffe 1994) that, if common, could shape community structure. There are also some studies that failed to find such interspecific effects (Hunter and Krebs 1979;Espmark 1999;Lohr 2008).…”

“…Species singing similar songs may also suffer fitness costs due to ambiguity in species recognition. For example, blue tits (Cyanistes caeruleus) suffer from territorial aggressiveness by the larger bodied great tits (Parus major), and in sympatry have character displacement of song (Doutrelant and Lambrechts 2001), which reduces interspecific aggression (Doutrelant et al 2000). Collared flycatchers (Ficedula albicollis) in sympatry with pied flycatchers (F. hypoleuca) also show character displacement of song, which in these species is primarily an epigamic signal, putatively to avoid hybridisation (Wallin 1986), but many male pied flycatchers learn mixed song types in sympatry (i.e.…”

Can the acoustic adaptation hypothesis predict the structure of Australian birdsong?

“…The best support has come from large-scale studies focusing on broad categories of habitat (e.g., dense forest vs open) for either a variety of species or a single oscine songbird found in a variety of habitats (Chapuis 1971;Morton 1975;Nottebohm 1975;Wasserman 1979;Ryan and Brenowitz 1985;Sorjonen 1986;Handford 1988;Wiley 1991;Tubaro and Segura 1994;Van Buskirk 1997). Studies that have focused on fewer species or tried to explain microstructural differences in long-distance signals have not consistently supported the AAH (Lemon et al 1981;Rothstein and Fleischer 1987;Smith and Yu 1992;Date and Lemon 1993;Williams and Slater 1993;Fotheringham et al 1997;Daniel and Blumstein 1998;Naguib and Wiley 2001; but see Doutrelant and Lambrechts 2001). The majority of these studies focused on some or all of the same Holarctic or Neotropical birds (but see Chappuis 1971; Slabbekoorn and Smith 2001).…”

Ecological correlates of song complexity in white-rumped munias

“…Existence of sympatric closely related species affects song trait, because song plays an important role for species recognition and mate choice (Grant & Grant 1996;Searcy & Yasukawa 1996;Seddon 2005). Distinctive specific features of song are facilitated via selection against interspecific competition or hybridization (de Kort, den Hartog & ten Cate 2002;Doutrelant & Lambrechts 2001;Gorissen, Gorissen & Eens 2006). Presence of predators also affects song.…”