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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.09.009 Byline: Henrik Brumm (a)(b), Robert F. Lachlan (a)(c), Katharina Riebel (a)(d), Peter J.B. Slater (a) Abstract: Why some bird species have evolved elaborate song repertoires has puzzled biologists for a long time. According to the antiexhaustion hypothesis avian song type repertoires have evolved because switching between different songs, involving different patterns of muscle contractions, causes less exhaustion in the singer and thus allows a higher song rate to be maintained. Although it is a classic explanation referred to in many textbooks, this hypothesis is still the subject of debate. We investigated the antiexhaustion idea in the chaffinch, Fringilla coelebs, a species in which males may have only one song type or a repertoire of up to six types. We analysed the song delivery rates of 101 male chaffinches, taking into account various seasonal, ecological and social variables. We found that males with a repertoire of several song types did not sing at a higher rate than males with only one song type, even though single song type males produced longer songs on average. Also, repertoire birds singing at high rates did not switch song types more often. These findings indicate that song type switching is not necessary for the maintenance of high song rates in this species. We conclude that preventing motor fatigue was not important in the evolution of chaffinch song type repertoires. Thus other factors, such as direct sexual selection of repertoire size or the use of song type repertoires for vocal interactions, are much more likely to explain why many bird species have evolved a repertoire of several song types. Author Affiliation: (a) School of Biology, University of St Andrews, U.K. (b) Communication and Social Behaviour Group, Max Planck Institute for Ornithology, Germany (c) Department of Biology, Duke University, U.S.A. (d) Institute of Biology, Leiden University, The Netherlands Article History: Received 2 March 2008; Revised 13 May 2008; Accepted 8 September 2008 Article Note: (miscellaneous) MS. number: 08-00145R

In studies of cumulative cultural evolution in non-human animals, the focus is most often on incremental changes that increase the efficacy of an existing form of socially learned behaviour, such as the refinement of migratory pathways. In this paper, we compare the songs of different species to describe patterns of evolution in the acoustic structure of bird songs, and explore the question of what building blocks might underlie cumulative cultural evolution of bird song using a comparative approach. We suggest that three steps occurred: first, imitation of independent sounds, or notes, via social learning; second, the formation of categories of note types; and third, assembling note types into sequences with defined structures. Simple sequences can then be repeated to form simple songs or concatenated with other sequences to form segmented songs, increasing complexity. Variant forms of both the notes and the sequencing rules may then arise due to copy errors and innovation. Some variants may become established in the population because of learning biases or selection, increasing signal efficiency, or because of cultural drift. Cumulative cultural evolution of bird songs thus arises from cognitive processes such as vocal imitation, categorization during memorization and learning biases applied to basic acoustic building blocks. This article is part of a discussion meeting issue 'The emergence of collective knowledge and cumulative culture in animals, humans and machines'. [ABSTRACT FROM AUTHOR]

Learned information is transmitted through fish populations in a nonrandom or directed manner and shoaling preferences may be a strong factor in the social transmission of novel foraging information or feeding preferences. These were indicated by results of an investigation of factors influencing the preferences of guppies for different shoals to clarify how information transmission occurs, given the evidence that shoaling can improve foraging success. Discrimination between shoal partners based on shoal size, size of shoaling fish, foraging experience and familiarity of shoaling fish was noted.

The use of information provided by others is a common short-cut adopted to inform decision-making. However, instead of indiscriminately copying others, animals are often selective in what, when and whom they copy. Howdo they decide which 'social learning strategy' to use? Previous research indicates that stress hormone exposure in early life may be important: while juvenile zebra finches copied their parents' behaviour when solving novel foraging tasks, those exposed to elevated levels of corticosterone (CORT) during development copied only unrelated adults. Here, we tested whether this switch in social learning strategy generalizes to vocal learning. In zebra finches, juvenile males often copy their father's song; would CORT-treated juveniles in free-flying aviaries switch to copying songs of other males? We found that CORT-treated juveniles copied their father's song less accurately as compared to control juveniles. We hypothesized that this could be due to having weaker social foraging associations with their fathers, and found that sons that spent less time foraging with their fathers produced less similar songs. Our findings are in line with a novel hypothesis linking early-life stress and social learning: early-life CORT exposure may affect social learning indirectly as a result of the way it shapes social affiliations. [ABSTRACT FROM AUTHOR]

Our understanding of bird song, a model system for animal communication and the neurobiology of learning, depends critically on making reliable, validated comparisons between the complex multidimensional syllables that are used in songs. However, most assessments of song similarity are based on human inspection of spectrograms, or computational methods developed from human intuitions. Using a novel automated operant conditioning system, we collected a large corpus of zebra finches' (Taeniopygia guttata) decisions about song syllable similarity. We use this dataset to compare and externally validate similarity algorithms in widely-used publicly available software (Raven, Sound Analysis Pro, Luscinia). Although these methods all perform better than chance, they do not closely emulate the avian assessments. We then introduce a novel deep learning method that can produce perceptual similarity judgements trained on such avian decisions. We find that this new method outperforms the established methods in accuracy and more closely approaches the avian assessments. Inconsistent (hence ambiguous) decisions are a common occurrence in animal behavioural data; we show that a modification of the deep learning training that accommodates these leads to the strongest performance. We argue this approach is the best way to validate methods to compare song similarity, that our dataset can be used to validate novel methods, and that the general approach can easily be extended to other species., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: DS is currently serving on the editorial board of PLOS Computational Biology., (Copyright: © 2024 Zandberg et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Most cooperative breeders live in discrete family groups, but in a minority, breeding populations comprise extended social networks of conspecifics that vary in relatedness. Selection for effective kin recognition may be expected for more related individuals in such kin neighbourhoods to maximize indirect fitness. Using a long-term social pedigree, molecular genetics, field observations and acoustic analyses, we examine how vocal similarity affects helping decisions in the long-tailed tit Aegithalos caudatus . Long-tailed tits are cooperative breeders in which help is typically redirected by males that have failed in their own breeding attempts towards the offspring of male relatives living within kin neighbourhoods. We identify a positive correlation between call similarity and kinship, suggesting that vocal cues offer a plausible mechanism for kin discrimination. Furthermore, we show that failed breeders choose to help males with calls more similar to their own. However, although helpers fine-tune their provisioning rates according to how closely related they are to recipients, their effort was not correlated with their vocal similarity to helped breeders. We conclude that although vocalizations are an important part of the recognition system of long-tailed tits, discrimination is likely to be based on prior association and may involve a combination of vocal and non-vocal cues. This article is part of the theme issue 'Signal detection theory in recognition systems: from evolving models to experimental tests'.

The use of information provided by others is a common short-cut adopted to inform decision-making. However, instead of indiscriminately copying others, animals are often selective in what, when and whom they copy. How do they decide which 'social learning strategy' to use? Previous research indicates that stress hormone exposure in early life may be important: while juvenile zebra finches copied their parents' behaviour when solving novel foraging tasks, those exposed to elevated levels of corticosterone (CORT) during development copied only unrelated adults. Here, we tested whether this switch in social learning strategy generalizes to vocal learning. In zebra finches, juvenile males often copy their father's song; would CORT-treated juveniles in free-flying aviaries switch to copying songs of other males? We found that CORT-treated juveniles copied their father's song less accurately as compared to control juveniles. We hypothesized that this could be due to having weaker social foraging associations with their fathers, and found that sons that spent less time foraging with their fathers produced less similar songs. Our findings are in line with a novel hypothesis linking early-life stress and social learning: early-life CORT exposure may affect social learning indirectly as a result of the way it shapes social affiliations.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'., (© 2018 The Authors.)