Introductory Talk

• Dianne Brunton (School of Natural Sciences, Massey University, New Zealand)

The complexity of birdsong: different measures and their implications for understanding animal communication

• Marc Naguib (Wageningen University, Netherlands)

Birdsong is among the main model system in animal communication. One reason is, next to its accessibility and biological function, the striking variability within and across species. This complexity raises interesting questions on the mechanisms, functions, and evolution of singing traits. Complexity of birdsong occurs at different levels, ranging from the phonological and syntactical structure of songs, the vocal repertoire size, sequential ordering of different syllables and songs to the use of songs in vocal interactions. Here I will address some of the complexities in singing styles across selected species covering examples from classical numerical approaches to quantify complexity to production-quality approaches and more holistic approaches, capturing variation in the more global parameter space. Quantifying the level of complexities at different levels will help understanding the internal processing mechanisms as well as the selection pressures that underly the complexity and eventually its communicative ffunction. By taking different approaches, the presentation highlights different levels of complexity and that simple comparison across individuals and species may not capture the meaningful variation in the respective communication system.

Communicative complexity in primates

• Claudia Fichtel (Leibniz Institute for Primatology, Göttingen, Germany)

Primates exhibit an astonishing diversity of communicative systems, with important variation in both the nature and the number of signals they produce. Although the link between social and communicative complexity has been supported across communicative modalities, several aspects of communicative complexity have not been systematically addressed. In this talk, I will give an overview about the link between social and communicative complexity in primates and address additional levels of communicative complexity such as context dependent meaning of vocalizations, vocal sequences, and how social learning contributes to communicative complexity.

A world beyond our understanding – the ultrasonic vocalization of mice

• Christine Pfeifle (MPI for Evolutionary Biology)

Humans and mice differ quite strongly in their communication means. The hearing range of mice is not identical to humans. Mice communicate within the human hearing range and out in a world beyond our perception in the ultrasonic spectrum (20 kHz - 110 kHz) Mice are vocalizing in our human hearing range if they want to warn others or are in distress. But mostly for social interactions they utter sounds in the ultrasonic region above 20kHz. I will show in this presentation an insight of these vocalizations including their complexity. Several studies show that this ultrasonic vocalization (USV) of mice is important for the exchange of social information. Mice communicate and transfer information in short syllables or longer calls consisting of several syllables in the ultrasonic range. In social interactions mice show this behavior: pups to parents, juvenile mice and within the mating context as well as interacting with the same sex. It is very important to be aware of the senses, which the research animal of interest is using, in order not to involuntary influence the animal behavior and in the end animal welfare.We will describe the fascinating world of ultrasonic vocalization and communication in mice. The recording and analysis of USV from mice could be used to monitor mice with minimal human interference. We try to understand the usage of the vocalization and the possible alteration because of human influences. In the end we will also show the potentials of this method as also the drawbacks and limits of this approach. References: von Merten, S., Hoier, S., Pfeifle, C., & Tautz, D. (2014). A Role for Ultrasonic Vocalisation in Social Communication and Divergence of Natural Populations of the House Mouse (Mus musculus domesticus). PLoS ONE, 9. Hoier S, Pfeifle C, von Merten S, Linnenbrink M (2016) Communication at the Garden Fence –Context Dependent Vocalization in Female House Mice. PLoS ONE 11(3): e0152255. doi:10.1371/journal.pone.0152255 Medina, C., Evaluating Ultrasonic Vocalization as a tool for assessing welfare in mice. Master thesis, 30.09.2021 RWTH Aachen

What makes a birds’ song complex and how do they do it?

• Michelle Roper (School of Natural Sciences, Massey University, New Zealand)

Songbird vocal communication ranges from simple, monosyllabic sounds through to complex song. Birdsong has generally been thought to be a male trait that is used only in the breeding season to attract mates and defend territories. However, we now know this is no longer a representative definition of birdsong as we are finding more species that sing year-round and have female song. This raises the question as to whether we can still rely on other features of birdsong, such as high complexity, to distinguish whether a songbird’s vocalisation is classed as a song. I aimed to explore whether measures of vocal complexity can distinguish between songs and calls within the honeyeater family, a large and diverse Australasian songbird clade. Of those with described vocal behaviour, 41 species are said to produce song and 41 species are song-less. I predicted that higher vocal complexity would correlate with a vocalisation classed as a song, but this was only supported for some measures of vocal complexity. By comparing vocal complexity with song presence, I will discuss whether this is an appropriate method to define song. This is especially important for large studies understanding the evolution of birdsong and the applicability of the term ‘song’ across taxa. The novel songbirds’ vocal organ, the syrinx, is also thought to play a role in why songbirds sing complex song. Fundamental frequency is one measure of complexity that has been highly linked to syrinx size. However, nothing is known on whether this relationship occurs across species and sexes at the family level. I will discuss the implications of preliminary results and what this may mean for the evolution of complex vocalisations within the songbirds.

Vocal complexity beyond solo songs: singing duels between male canaries

• Pepe Alcami (LMU (Munich), MPI for Biological Intelligence (Seewiesen))

Singing by songbirds is a complex, culturally learned motor skill acquired during juvenile development and in some songbird species also before the onset of the breeding season. Outside of these specific periods, it is believed that the singing motor program is stable or ‘crystallized’, and 'solo' songs are used to illustrate the complexity of birdsong learning and production. I will show that in canaries (Serinus canaria), social interactions during the breeding season induce changes in birdsong. Using custom-made telemetric backpack technology to monitor song-based communication from freely behaving canaries, we find that adult males temporally overlap their songs during aggressive ‘duels’. Singing duels are characterized by increased song length, thereby enhancing singing performance and flexibility of a sexually selected behaviour. Our finding reveal song plasticity during male-directed singing in social environments, providing a model of fast plasticity of complex motor skills during singing dueling contests in which birds co-vary their songs online.

ECR Talk

• Julia Kovacs (PhD student - School of Natural Sciences, Massey University, Auckland campus)

Conversation about careers, progression, social networking for early career researchers in field related to the workshop. Co-lead by Dr Michelle Roper .

Mechanisms of hormone dependent singing of songbirds

• Manfred Gahr (MPI for Biological Intelligence, Seewiesen)

In temperate songbirds, song is seasonal and therefore often dependent on gonadal hormones, testosterone and its androgenic and estrogenic derivatives. Elevated testosterone levels at the beginning of the breeding season lead to species-typical song patterns. Canaries are seasonal singers in which song is highly organized in the breeding season and variable in the non-breeding season. This seasonality can be mimicked by testosterone treatment in female canaries that do not otherwise sing. Most brain areas that are part of the song-controlling neural circuitry, as well as the syrinx, express androgen receptors and, in the case of the song-controlling area HVC of canaries, additional estrogen receptors. These receptors are ligand-activated transcription factors that alter the transcriptome of the target cells of the song-controlling brain areas. As a result of these transcriptional changes, the neural circuits of the singing areas change in structure and function, affecting the patterning of singing. Here I describe a cascade of testosterone-induced molecular and electrophysiological events in the HVC that parallel testosterone-induced song in the canary.

Wrestling with the nature of vocal complexity: lessons from songbirds and hummingbirds.

• Nadje Najar (University of California Riverside, USA)

A thought-provoking conversation about what complexity actually is, what it isn't, and why we think the way we do about it.

Song structure and song ecology of wild zebra finches

• Hugo Loning (Wageningen University, Netherlands )

Songbirds sing to defend their territory and to attract partners. However, zebra finches (Taeniopygia guttata) are not territorial, they find their partner when young, and partners mate for life. Therefore, conventional theory predicts that zebra finches should not sing much at all. Yet, they do and their individually recognisable song is the focus of hundreds of lab-based studies. I here studied zebra finches in a wild population in Australia and I characterised many aspects of their song ecology. I show that wild zebra finch song is not linked primarily to breeding and mate choice but also to various other social activities. I discuss: 1.) which potential functions this may indicate, and 2.) the role of their individually distinct songs in this. Co-authors: Simon C Griffith2, Marc Naguib1 1 Behavioural Ecology Group, Wageningen University & Research, The Netherlands 2 Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia

The roles of multimodal signals in songbird vocal communication

• Nao Ota (MPI for Biological Intelligence, Seewiesen)

One of the factors which makes animal communication complex is the multimodality. Estrildid finches are one of the most studied songbird families for acoustic communication. They often combine their songs with body movements (i.e., dance) during courtship. However, there are still few empirical studies on the behavioral mechanisms and functions of dancing compared to songs. Our study species, blue-capped cordon-bleus (Uraeginthus cyanocephalus), perform characteristic dance displays in both sexes. During courtship, they repeatedly bob up and down and sing songs several times. We have previously found that they perform human tap-dance-like high-speed movements, tapping their legs on the perch two to six times in a single bobbing. Their behavior is interesting not only because both sexes perform almost the same display but also because their dance movements can produce non-vocal sounds and vibrations. Here we present our findings on the dance behavior and its relationship with songs in cordon-bleus. Our laboratory and field studies suggest that the sounds and vibrations by dancing can function as communication signals and have multifaced functions depending on the social and environmental contexts. It underscores the importance of considering the non-vocal aspects of bird acoustic communication toward a better understanding of animal communication systems and their complexities.

Song discrimination and neurogenetic mechanisms in nestling flycatchers

• Fanny-Linn H. Kraft (Stockholm University, Sweden)

For many bird species, songs play a central role in mate choice, and birdsong has been implicated as a possible driver of avian speciation. However, songs are socially learned, and the songs young birds experience influence the songs they produce later in life. This raises questions as to how innate biases play a part in enabling young birds to learn the song of their own species in an acoustically diverse environment. We can address some of these questions by investigating how young birds respond to songs, before the song learning process is complete. Nestling flycatchers have an innate response to conspecific song, but the underlying neural mechanisms are unknown. To better understand how the song learning process affects speciation, my colleagues and I have aimed to investigate whether the innate response to song is reflected in the neurogenetic mechanisms involved in song learning. We exposed nestlings of two closely-related flycatcher species (Ficedula hypoleuca and F. alcicollis) to conspecific and heterospecific song. We then examined gene expression in brain regions involved in song memory (NCM, CMM, and field L) using a low-input RNA-seq technique. In this workshop, I will present our initial gene-expression results. I will also present results from other studies I have been working on, investigating similar questions in this system. The results from these studies will have implications for the neural basis of early-life song discrimination and reproductive isolation in songbirds.

Measuring communicative complexity across taxa: food for thought

• Louise Peckre (Independent researcher, France)

Communication is crucial in social relationships, and its complexity is acknowledged to coevolve with social complexity. The social complexity hypothesis for communicative complexity is widely supported, yet there is a lack of clarity around what researchers refer to as ‘communicative complexity’. By illustrating my points with examples from the available literature and my own research, I will first argue that more specific and holistic definitions of communicative complexity are both essential to capture the complexity of communicative systems. First, loose definitions might be responsible for apparent contradictory results across different taxa (e.g., when looking across human and non-human literature). In addition, many studies reduce communicative complexity to a unique proxy in a unique communicative modality, impacting the accuracy of conclusions. Finally, based on these considerations, I further aim to offer a critical and updated overview of current attempts to assess communicative complexity across taxa. An updated integrative perspective on communicative complexity might unlock the door to a better understanding of the mechanisms behind the observed co-evolution of sociality and communication.

Song diversity, innovation and reproductive success – using field-based experiments and conservation practice to understand the cultural evolution of song.

• Dianne Brunton (School of Natural Sciences, Massey University, New Zealand)

New Zealand has successfully used invasive species eradications and threatened species translocations to successfully conserve many avian species from extinction – using a network of islands and protected sanctuaries. These conservation approaches also provide an opportunity to undertake field-based experiments and research aimed at understanding song diversity and cultural evolution in free living birds. I will present our song research on two species: the North Island Saddleback/Tieke (Philesturnus rufusater) and the NZ bellbird/Korimako (Anthornis melanura). Tīeke are territorial, long lived and establish local male song dialects. We used the translocation history of this species to quantify Tīeke song and found that distinct song lineages have evolved rapidly. We then used real-world experiments to test whether this rapid evolution of song cultures impedes genetic mixing when translocations include multiple cultural sources – limited assortative mating occurs and novel songs arise in first year males. In contrast, Korimako is a species with good dispersal abilities, where both males and females sing. For this species we examined spatial and sex-based differences in song and explored the relationship between song and reproductive success for both sexes.

Bird migration - complex, versatile and flexible

• Miriam Liedvogel (Institute of Avian Research, MPI Evolutionary Biology )

Understanding the genetics of bird migration is a long-standing goal in evolutionary biology. Blackcaps Sylvia atricapilla are ideal for this work as different populations exhibit enormous difference in migratory behaviour and little else. We characterize (i) phenotype, population structure and demographic history the blackcap, and (ii) identify sequence variants and signaling pathways that are associated with variation of the migratory phenotype. My talk covers insight from classical studies on selection and cross-breeding experiments, tracking approaches in the wild, to finally introducing novel insight from using a de novo assembled genome of the blackcap as reference for large scale demographic study with different phenotypes across their breeding range.

New frontiers in bird migration. How individual and social learning shape migratory behavior.

• Andrea Flack (MPI of Animal Behavior, Konstanz, Germany)

In my group, we elucidate the elements that shape short-term migratory decisions using various experimental and observational approaches. Using state-of-the-art high-resolution biologging in combination with experimental approaches like delayed-releases, and translocations, we are exploring the underlying causes for behavioral variation among individuals from within and across populations.

Talk

• Auguste von Bayern (MPI for Biological Intelligence)

tbd