Habitat structure and the evolution of bird song: a meta‐analysis of the evidence for the acoustic adaptation hypothesis

Abstract

1.Habitat structure has been considered as a main factor shaping the evolution of bird song acoustics. 2. Based on expected differential patterns of sound degradation in different habitats, the acoustic adaptation hypothesis (AAH) proposes that songs with lower frequencies, narrower frequency ranges and longer inter-element intervals should occur more frequently in densely vegetated compared with herbaceous habitats. 3. Empirical tests of the AAH have provided mixed results. Here, we review for the first time the literature on this topic using a meta-analytical, quantitative approach. 4. Maximum, minimum, peak frequency and frequency range were found to be significantly lower in closed compared with open habitats, but the mean size of the effect of habitat was small. Inter-element intervals were not affected by habitat structure. 5. The AAH implicitly assumes that birds are selected to maximize song broadcast range and minimize degradation, while it neglects the potential role of energetic costs of singing and selection by eavesdroppers (e.g. predators and parasites). 6. Our meta-analysis supports the AAH, but habitat structure only weakly predicts the acoustical properties of bird songs. Thus, other potentially relevant factors should be included in realistic models of the evolution of bird song acoustics.

Environmental variability and acoustic signals: a multi-level approach in songbirds

“…Alternatively, this may be a by-product of selection for innovation and cognition [9], but additional work is needed to clarify the precise sources of selection. Despite considerable evidence for signal adaptation to different habitats as gauged through their averaged values [2,3], no variables explained intraspecific song variability that would reflect local adaptation to environmental conditions. In contrast, because environmental seasonality explained intraindividual song variation, selection may favour song variability to cope with different acoustic environments that an individual encounters throughout its life or even shorter timescales such as a single breeding season or day.…”

“…For acoustic mating signals, adaptive signal evolution in response to local habitat features has often been referred to as the acoustic adaptation hypothesis and is well documented in birds [2,3]. Evidence for acoustic adaptation has typically been restricted to comparisons between strongly dissimilar habitats [2], often without considering a key aspect of the sensory drive hypotheses: the strength of sexual selection [2,3], which, when strong, should favour song traits that are more readily perceived by females for mate-choice criteria [1]. Additionally, most studies have used acoustic traits (e.g.…”

Spectral characteristics of intense mew calls in cat species of the genus Felis (Mammalia: Carnivora: Felidae)

“…Morton 1975;Waser and Waser 1977;Wallschläger 1981Wallschläger , 1985Brown and Waser 1988;Wiley 1991;Brown and Gomez 1992;Brown et al 1995;Daniel and Blumstein 1998;Slabbekoorn and Smith 2002;Ryan and Kime 2003;Saunders and Slotow 2004;Blumstein and Turner 2005;Boncoraglio and Saino 2007). Data on diverse vertebrate taxa support this hypothesis (Morton 1975;Gish and Morton 1981;Wallschläger 1980Wallschläger , 1982Wallschläger , 1985Wallschläger and Nikolskij 1985;Masters 1991;Saunders and Slotow 2004;Slabbekoorn 2004;Seddon 2005;Nicholls and Goldizen 2006;Tubaro and Lijtmaer 2006), while in other taxa it is only supported weakly (Blumstein and Turner 2005;Boncoraglio and Saino 2007) or is not supported (Daniel and Blumstein 1998;Kime et al 2000;Saunders and Slotow 2004). In all types of natural habitat, the height of the signal source and that of the receiver are important factors in acoustic communication (Kime et al 2000;Slabbekoorn 2004), although the relative importance of the elevation above ground may be different for sender and receiver (Mathevon et al 2005).…”

“…This study specifically evaluates the spectral characteristics of intense mew calls in the six different taxa within the concept of a general ''frequency scaling rule'' for acoustic signals in vertebrates, as expanded and quantified by Fletcher (2004Fletcher ( , 2007, and within the framework of the acoustic adaptation hypothesis (Daniel and Blumstein 1998;Kime et al 2000;Saunders and Slotow 2004;Boncoraglio and Saino 2007).…”

Distinct song parts of the endemic marsh grassbird of China vary with latitude and climate among migratory and sedentary populations

“…Ellers and Slabbekoorn 2003). Furthermore, song evolution may be shaped by morphological and physical constraints (Podos and Nowicki 2004) as well as environmental conditions (Boncoraglio and Saino 2007;Ey and Fischer 2009).…”