A comparative study of the function of heterospecific vocal mimicry in European passerines

Abstract

Although heterospecific vocal imitation is well documented in passerines, the evolutionary correlates of this phenomenon are poorly known. Here, we studied interspecific variation in vocal mimicry in a comparative study of 241 European songbirds. We tested whether vocal mimicry is a mode of repertoire acquisition or whether it resulted from imperfect song learning. We also investigated the effect of the degree of contact with the vocal environment (with species having larger ranges, abundance, or being long lived having a higher degree of mimicry) and a possible link with cognitive capacity (an overall larger brain in species with mimicry). Finally, we determined the potential evolutionary role of vocal mimicry in different interspecific contexts, predicting that mimicry may affect the intensity of brood parasitism, predation, or degree of hybridization. While controlling for research effort and phylogenetic relationships among taxa, we found that effect sizes for intersong interval, brain size, breeding dispersal, abundance, age-dependent expression of repertoires, and predation risk reached a level that may indicate evolutionary importance. Vocal mimicry seems to be a consequence of song continuity rather than song complexity, may partially have some cognitive component but may also be dependent on the vocal environment, and may attract the attention of predators. However, estimates of sexual selection and interspecific contacts due to brood parasitism and hybridization varied independently of vocal mimicry. Therefore, mimicry may have no function in female choice for complex songs and may be weakly selected via interspecific associations. These findings provide little evidence for vocal mimicry having evolved to serve important functions in most birds.

Climatic Patterns Predict the Elaboration of Song Displays in Mockingbirds

“…A second possibility is that the relationship between climate and song is driven by variation in the strength of female preferences for signals that provide specific information about a male's ability to learn and innovate (see [14, 21–23]). Cognitive skill could be an important mate choice criterion in omnivorous species such as the ones considered here because good short-term learning and decision-making abilities may be critical for foraging (and thus provisioning rates), acquisition of all-purpose territories, selection of nest sites, and timing of breeding.…”

“…First, stronger selection in more variable and unpredictable climates could lead to the elaboration of signals of quality [14, 17–20]. Alternatively, selection for enhanced learning and innovation in more variable and unpredictable climates might lead to the evolution of signals of intelligence in the context of mate attraction [14, 21–23]. …”

Imitating Sounds: A Cognitive Approach to Understanding Vocal Imitation

“…From this perspective, vocal imitation provides a way for naïve youngsters to acquire the communicative abilities of mature adults. In fact, some researchers have argued that copying of sounds outside the natural repertoire may be a functionless evolutionary artifact (Garamszegi, Eens, Pavlova, Aviles, & Moller, 2007;Lachlan & Slater, 1999). Although vocal imitation abilities can be an important component of vocal development, the most versatile vocal imitators are adult humans (Amin, Marziliano, & German, 2012;Majewski & Staroniewicz, 2011;Revis, De Looze, & Giovanni, 2013).…”

Fork-tailed drongos use deceptive mimicked alarm calls to steal food

“…Many animals mimic the vocalizations of other species [1,2], yet there is little evidence of a function for this behaviour [3,4]. Hypotheses suggest that vocal mimicry may be used in interspecific communication to manipulate the behaviour of other species to the advantage of the vocal mimic (reviewed by [4]).…”