Does the song of conspecifics affect the reproduction of birds? This question was investigated in an Austrian-Slovak study led by the University of Veterinary Medicine Vienna and published in the “Journal of Ornithology”. The behavior of the European reed warbler (Acrocephalus scirpaceus) was examined in an experiment using song playbacks. The findings revealed that the acoustic environment, particularly the “beautiful” songs of males in the neighborhood have a positive effect on reproductive investment and breeding success.

At the onset of the breeding season, several critical decisions must be made such as where to establish a territory and attract a mate and identify an ideal breeding site. These decisions can be influenced by the quality of potential mates, but also by the presence of other conspecifics in the environment. In birds, for example, vocal characteristics such as the complexity of a song can signal the quality of an individual.

Playback experiments test the effect of songs

“In addition to choosing the right location for reproduction and attracting mates, we suspect that the acoustic environment, for example in the form of singing neighbors, can also influence an individual´s reproductive,” explains study lead author Herbert Hoi from the Konrad Lorenz Institute of Ethology (KLIVV) at Vetmeduni, outlining the research hypothesis of the study. In particular, early maternal investment, like the resources that a mother allocates to her embryos in the eggs, is a sensitive factor that can also be influenced by the quality and attractiveness of males. This investment is reflected in the distribution of maternal resources among the offspring and ultimately affects also their development.

“In this context, we investigated whether the song quality of neighboring conspecifics stimulates reproductive parameters in the reed warbler,” says Herbert Hoi. To this end, the scientists carried out playback experiments in the field with songs of high and low complexity, simulating different acoustic environments and assess their influence on settlement decisions, early maternal investment and breeding success.

“Beautiful” bird songs have a positive effect

While the results revealed no significant difference in the number of nests and the start of egg laying, the nests were found to be significantly closer to locations where highly complex songs were heard. In addition, a significantly higher proportion of eggs were completely dark pigmented in the group exposed to highly complex songs than in the group with less complex songs. Furthermore, the breeding success of nests near highly complex songs was significantly higher, resulting in more offspring.

Herbert Hoi concludes: “Our results suggest that the acoustic environment, for example in the form of song quality, not only from male partners but also conspecifics, has a notable influence on reproductive investment and breeding success. This influence appears to be less pronounced regarding investment in embryos.” Given the importance of offspring loss due to nest predation, Hoi suggests that future studies could explore the role of neighboring males' songs and their impact on behaviors during other reproductive phases.

The article „Does complexity of conspecific song influence reproductive decisions and investment in European Common Reed Warblers: an experimental playback approach?“ by Ján Krištofík, Alžbeta Darolová, Lucia Rubáčová und Herbert Hoi was published in „Journal of Ornithology“.

Scientific article

The hormone oxytocin is known to regulate a range of behaviours in mammals, particularly in females. In addition to the known reproductive functions, studies in mice show that oxytocin released centrally in the brain influences a range of social behaviours. In females, for example, these include social preferences for mates of the opposite and same sex. A study at the University of Liverpool published with the participation of the University of Veterinary Medicine Vienna now shows that female mice benefit from higher levels of oxytocin in the rearing of their offspring through improved co-operation.

In their study, the scientists investigated the behaviour of related female house mice (Mus musculus domesticus). Female house mice can choose whether to raise their young in so-called communal nests with another female and her young, or alone in a single nest. In the study, they found that when females reared their young together, mice with higher central oxytocin levels had more egalitarian and successful co-operative relationships. ‘The cooperation of two sisters with high oxytocin concentrations in the paraventricular nucleus (PVN) of the hypothalamus resulted in a communal nest in which the sisters produced more offspring together, had more equal contributions to the number of young and spent more equal proportions of time in the nest,’ says study joint first author Stefan Fischer from the Konrad Lorenz Institute of Ethology (KLIVV) at Vetmeduni .

Influence of oxytocin sheds new light on the evolution of egalitarian social relationships

In contrast to the relationship between oxytocin concentrations and the number of offspring produced in a communal nest, oxytocin concentrations were not related to the number of weaned offspring produced in a single nest without co-operation. In addition, oxytocin levels did not differ with regard to the availability of preferred nest sites or social competition with other groups of mice. ‘Given that we associate the positive effects of co-operation with oxytocin, our results have far-reaching implications for understanding the evolution of egalitarian social relationships,’ explains Fischer.

Despotic or egalitarian: social systems are characterised by a tension between competition and cooperation

According to Fischer, social competition and cooperation fundamentally characterise the social systems of animals living in groups. Sociality is always the outcome between the tension of group members to fight or co-operate for resources and reproduction. Whether group members tend to fight or co-operate depends on the relatedness of the interacting animals and the benefits of cooperation. This tension is reflected in the differential distribution of the benefits of cooperative behaviour between group members. In egalitarian social systems, the benefits are distributed relatively evenly according to the effort invested, whereas in despotic social systems the benefits tend to accrue to the dominant individuals - at the expense of the others. ‘Our study is of particular interest because it provides evidence for differences in the balance between egalitarian and despotic behaviour that are related to central oxytocin levels of cooperating individuals. If similar variations are replicated in other social species, this could help us to understand the proximate factors that influence egalitarian and despotic social behaviour and thus provide a comprehensive insight into the diversity of social systems,’ emphasises Fischer.

The article „Egalitarian cooperation linked to central oxytocin levels in communal breeding house mice“ by Stefan Fischer, Callum Duffield, William T. Swaney, Rhiannon L. Bolton, Amanda J. Davidson, Jane L. Hurst and Paula Stockley was published in „Communications biology“.

Scientific article

Sleeping is restorative and has a considerable influence on the metabolism, among other things. The extent to which the common whitethroat (Curruca communis) - a migratory bird native to large parts of Europe in summer and sub-Saharan Africa in winter - utilises this fitness advantage during its intercontinental flights was investigated in a recently published study led by the University of Veterinary Medicine, Vienna. According to the study, these feathered long-haul travellers only partially rely on the energetic benefits of sleep. Instead, they tend to concentrate on foraging.

In their study, researchers from Italy and Austria investigated the relationship between sleeping behaviour and posture, metabolic state and energy conservation strategies during bird migration in the whitethroat warbler. The fieldwork was carried out on the island of Ponza, located around 50 km off the west coast of Italy and an important stopover site on one of the most important migration routes for Palaearctic passerines.

Metabolic benefits from sleep are not fully utilised

"We were able to confirm that sleeping in a crouched position leads to energy savings in the metabolism, which results in lower vigilance and an associated higher vulnerability to predators. However, the birds showed no changes in their sleeping behaviour in response to the amount of energy reserves stored," says Ivan Maggini from the Konrad Lorenz Institute of Ethology (KLIVV) at Vetmeduni Vienna, outlining the key research findings.

According to Maggini, this indicates that the songbirds do not fully utilise the metabolic benefits of sleep, at least in the observed phase of their migration. "We suspect that whitethroats prefer foraging to sleeping for optimal energy management and to maximise efficiency during their stopovers," says the researcher.

Important new findings for nature conservation

According to the researchers, the underlying ecological causes require further studies and a comparative approach. This is particularly important as only long-distance migratory birds have been studied so far, meaning that it is not yet known how species with shorter migrations deal with sleep. In general, studies on sleep are important for nature conservation, as they show how migratory birds use the various resting places. Maggini comments: "These findings are essential in order to maintain and improve the environmental conditions at these resting places, as the survival of numerous bird species depends on them."

Sleep is essential for survival during bird migration

Resting places, where birds rest and replenish their energy reserves, play an important role in overcoming the challenges associated with bird migration. While sleep is considered vital for all organisms, it becomes even more important during migration, when energy management becomes a matter of survival - as previous studies have clearly demonstrated.

The article „Sleep Posture Influences Metabolic Rate and Vigilance in the Common Whitethroat (Curruca Communis)“ by Maia Pastres, Ivan Maggini, Massimiliano Cardinale, Leonida Fusani and Andrea Ferretti was published in „Integrative and Comparative Biology“.

Scientific article

The way birds sing is important in mate choice. This is well-known from behavioural research. But what characteristics of birdsong are important for competition between male birds? An international study led by the University of Veterinary Medicine Vienna used a playback experiment to investigate this question using reed warblers (Acrocephalus scirpaceus) - a native songbird that overwinters in sub-Saharan Africa. According to the study, monotonous repetitions of bird song syllables convey dominance. So, do stereotypical singers have an advantage?

In behavioural research, the virtuosity (complexity) with which a male bird performs his song has long been identified as an important criterion in female mate choice. In contrast, the role of song in interactions between rivals is less clear - and very little is known about which song characteristics are particularly important in territory defence and confrontations between males.

One way of getting your point of view and opinions across to the ‘man’ (addressee) clearly and emphatically is to repeat the ‘message’ to be conveyed. We humans also use repetition to emphasise statements and make them more credible. In reed warblers, males increase their song complexity to impress females, while they reduce it in territorial disputes. One way to reduce song complexity is by repeating individual syllables. In their recently published study, the team of scientists therefore investigated the importance of repeating syllables during territorial disputes with rivals.

Playback experiment with different frequencies of syllable repetition

The researchers hypothesised that the repetition of syllables signals a male's general fighting ability, aggressive status, or willingness to attack. Study lead author Herbert Hoi from the Konrad-Lorenz Institute of Ethology (KLIVV) at Vetmeduni explains: ‘In a playback experiment, we investigated the behavioural response of unmated, territorial reed warbler males to two intruders singing at the same time, whereby the song of the two intruders simulated by playbacks differed in the extent of syllable repetition.’

A clear behavioural response: those who repeat themselves demonstrate dominance

The reaction of the territory holder was determined using several behavioural parameters. The results showed that the complexity of the song does not play a role in whether the males dare to approach the playback or how close they come. However, it turned out that territory holders approached more quickly and stayed significantly longer in the vicinity of the complex playback song, i.e. the one with few repetitions.

‘This weaker response to the song with many repeated syllables suggests that territorial males are more intimidated by the aggressive nature of this type of song,’ says Herbert Hoi. However, as the other differences in response were rather weak in relation to the extremely divergent song characteristics in the playback experiment, Hoi believes that it would be interesting for future studies to investigate the social status and motivation of those males that seek the proximity of a conspecific that embodies one or the other song type.

The article „Is syllable repetitions a song parameter important for male-male interactions in Eurasian reed warbler (Acrocephalus scirpaceus)?“ by Alžbeta Darolová, Ján Krištofík, Lucia Rubáčová, Felix Knauer and Herbert Hoi was published in „Biologia“ .

Scientific article

Starting in Zurich (Switzerland), the StadtWildTiere project has since been expanded to a total of 13 cities in Austria, Germany and Switzerland, including Vienna and Berlin. Observations of random encounters with wild animals in urban neighbourhoods are collected on a joint online platform. In Austria, reports can be submitted via the website www.stadtwildtiere.at.  A recently published international study involving the University of Veterinary Medicine Vienna has now analysed the benefits of this transnational initiative.

StadtWildTiere collects sightings of wildlife in cities to raise awareness of biodiversity in urban areas throughout Central Europe. The collection of data also serves as a basis for scientific analyses. Furthermore, the knowledge collected by the citizens is used to promote nature and biodiversity in urban areas.

Climate change, interactions:
Community project uncovers the unknown for the first time

Urban ecology is still a young field and urban wildlife populations have not yet been the focus of many studies. "StadtWildTiere enables us to recognise previously hidden patterns and temporal trends, e.g. in the context of urban densification and the heat island effect, particularly with regard to climate change. The initiative can therefore also serve as a sensor for future interactions between humans and wildlife," explains study co-author Theresa Walter from the Research Institute of Wildlife Ecology at Vetmeduni.

Important basis for decisions at political level

In the long term, the scientists suggest that projects such as StadtWildTiere should create a basis for comparative, international monitoring in order to close the existing gaps in knowledge about urban wildlife populations. According to study co-author Richard Zink from the Konrad Lorenz Institute for Comparative Behavioural Research (KLIVV) at Vetmeduni, the data obtained from the study goes far beyond science: "This knowledge is also of crucial importance for political decision-makers and wildlife managers in order to establish the right strategies and measures. In particular, this also concerns the question of how to effectively improve biodiversity in cities."

The article „StadtWildTiere – added value and impact of transnational urban wildlife community science projects“ by Madeleine Geiger, Anouk Lisa Taucher, Sandra Gloor, Mirco Lauper, Sarah Kiefer, Sophia E. Kimmig, Janette Siebert, Theresa Walter, Richard Zink, Fabio Bontadina and Daniel Hegglin was published in „Frontiers in Ecology and Evolution“.


Scientific article

StadtWildTiere Österreich

Migratory landbirds, particularly those bound for sub-Saharan Africa, are experiencing a decline across their range. The conservation of these species presents a formidable challenge due to the vast geographic span of their habitats. To effectively safeguard these birds, it is crucial to understand the obstacles they encounter not only within their breeding territories but also along their migratory paths and in their wintering locales. Regrettably, our knowledge is often limited by insufficient research capabilities throughout much of their range. Addressing this gap necessitates the establishment of a robust network of collaborative research efforts along the migratory flyways and the enhancement of research capacity in areas where it is currently lacking. Subsequently, key stakeholders must be engaged to actualize conservation measures.

A significant stride has been made with the initiation of the EUFLYNET COST Action, spearheaded by Dr. Ivan Maggini from the Konrad-Lorenz Institute of Ethology at the Vetmeduni. Funded by the EU, COST (Collaboration for Science & Technology) aims to foster networking and knowledge transfer. Launched in October 2023, EUFLYNET will span four years, orchestrating research coordination and facilitating knowledge exchange among scientists studying a broad spectrum of European migratory bird species. The network already boasts 160 members from 37 nations and is poised for further expansion. The inaugural in-person EUFLYNET assembly took place in Jastarnia, Poland, from February 28th to March 1st, 2024, convening approximately 100 participants who deliberated on collaborative ventures and received training on pertinent subjects such as statistical modeling, radiotracking, and tracking data analysis. We eagerly anticipate the forthcoming endeavors of this pivotal Action! For more information, please visit the Action website here: www.euflynet.eu.

The East African Lake Tanganyika is known worldwide for its colorful ornamental fish. The Princess of Lake Tanganyika (Neolamprologus pulcher), one of the most popular of these small cichlids, has now been studied by a team of scientists from the University of Veterinary Medicine, Vienna. The aim was to develop for the first time a simple test to investigate cognitive abilities of a wide range of fish in their natural habitat.

Cognitive abilities vary within and between species. Scientists propose several hypotheses to explain this variation. Two of the best-known hypotheses on the evolution of cognition relate an increased social complexity on the one hand and habitat complexity on the other to higher cognitive abilities.

Several studies have tested predictions derived from these two hypotheses, but only rarely under natural conditions with wild animals and not at all using free-living fish. "However, this is of particular importance if we want to link cognitive abilities with fitness-relevant factors in order to better understand the evolution of cognition," says study first author Arne Jungwirth from the Konrad Lorenz Institute of Ethology (KLIVV) at the University of Veterinary Medicine, Vienna.

First test to investigate cognitive abilities of fish in their natural habitat

According to the researchers, the biggest hurdle in assessing cognitive abilities in the wild has so far been finding a suitable set-up that is easy to use under field conditions. The research team set itself the goal of creating a test that was as simple as possible and could also be used with a variety of fish in their natural habitat.

Stefan Fischer from KLIVV, last author of the study, explains how this was achieved: "We developed a detour test in which the fish had to swim around an obstacle in order to reach a food reward." By altering the difficulty of the task, the behavioural researchers confirmed that this set up is a valid test for investigating the cognitive abilities of wild groups of Neolamprologus pulcher.

Hypothesis testing yields inconsistent results

They then tested specific predictions of the two main hypotheses on cognitive evolution using the most difficult test configuration. "In particular, we examined the differences in cognitive abilities between groups of different sizes inhabiting habitats of different complexity. However, neither hypothesis could be clearly verified in this first pilot study," says Arne Jungwirth. However, the scientists emphasise that the experimental set-up they have developed opens up the possibility of answering a whole range of research questions. Stefan Fischer comments: "We expect that the test we have developed will contribute to a better understanding of the evolution of cognitive abilities in the wild."

The article „Estimating Cognitive Ability in the Wild: Validation of a Detour Test Paradigm Using a Cichlid Fish (Neolamprologus pulcher)“ by Arne Jungwirth, Anna Horsfield, Paul Nührenberg and Stefan Fischer was published in „Fishes“.

Scientific article

Mercury is an environmental pollutant that raises concerns worldwide due to its toxicity and risks to both wildlife and human health – a point emphasized by the World Health Organization (WHO). This environmental toxin is found even in remote, untouched areas such as the Amazon, endangering the local wildlife. This is revealed in a recently published international study led by the Konrad Lorenz Institute for Comparative Behavioral Research (KLIVV) at the University of Veterinary Medicine Vienna, focusing on the poison frog Dendrobates tinctorius.

Artisanal and small-scale gold mining (ASGM) has become a major threat to South American forests. This method of gold extraction is a significant cause of small-scale deforestation and the largest contributor to mercury emissions into the atmosphere and freshwater systems worldwide. Previous studies have already highlighted the effects of mercury accumulation on various aquatic ecosystems and organisms. However, the consequences for other systems, such as small water-retaining plant structures (phytotelmata) and the organisms living within them, have gone unnoticed until now.

Focus on aquatic nurseries of Dendrobates tinctorius

A research team led by KLIVV at Vetmeduni (study's first author Lia Schlippe-Justicia; study's last author Bibiana Rojas) investigated this issue in French Guiana, focusing on the native poison frog Dendrobates tinctorius. The researchers focused on phytotelmata, small pools, for example, in the root area of plants, and other aquatic microenvironments, such as water in discarded containers.

High mercury levels from an early stage

In these typical breeding sites for Dendrobates tinctorius tadpoles, the researchers found high mercury concentrations. "In 17% of cases, we were able to detect very high mercury concentrations, particularly near known ASGM sites. However, we could not observe any influence of mercury concentration on the number of tadpoles in a given pool," says Lia Schlippe-Justicia. Tadpoles were also found in pools with extremely high concentrations, up to 8.68 ppm, suggesting that "D. tinctorius fathers do not seem to avoid pools with high mercury concentrations for tadpole deposition," according to Schlippe.

Negative effects on physical development

The research team also documented a significantly negative impact on amphibians, as reported by Bibiana Rojas: "Tadpoles in later developmental stages exhibited poorer body condition when growing up in pools with higher mercury concentrations. This underscores the need for further field and experimental studies examining the effects of mercury contamination on tadpole development and behavior, as well as the overall preservation of biodiversity in the Amazon."

The article „Poison in the nursery: Mercury contamination in the tadpole-rearing sites of an Amazonian frog“ by Lia Schlippe-Justicia, Jérémy Lemaire, Carolin Dittrich, Martin Mayer, Paco Bustamante and Bibiana Rojas was published in „Science of the Total Environment“.

Scientific Article

Due to their long life expectancy, naked mole rats are particularly suitable for researching mechanisms that maintain cellular function and slow aging. If these mechanisms could be solved, then the results could be relevant for humans aging and the development of cancer. An international study involving the University of Veterinary Medicine Vienna (Konrad Lorenz Institute for Ethology; KLIVV) is now providing important new insights into how adult stem cells affect long-term tissue maintenance using naked mole rats and their intestinal tract.

Naked mole rats (Heterocephalus glaber) are very special mammals. The animals, which are a maximum of 15 centimeters in size, live in large underground burrows and colonies of up to 300 animals in the semi-deserts of East Africa and are the only species of the genus Heterocephalus. Not only are they extremely social, their life expectancy is also unusually long and significantly exceeds that of other rodents. Because of this property, they offer scientists a unique opportunity to explore how evolution has influenced adult stem cell (ASC) activity and tissue function as life expectancy increases.

In mammals and other multicellular organisms, long-term maintenance of tissue homeostasis requires strict regulation of adult stem cell activity to ensure efficient repair and regeneration. In high-turnover mammalian tissues such as the intestine, the balance is controlled primarily by the continuous division and differentiation of the ASC and the subsequent cell death (apoptosis) of the mature cells. The longer survival of ASCs puts them at increased risk of mutations and reduces their fitness, which is evident in aging and in diseases such as cancer.

Intestinal tract with numerous cellular peculiarities

With this in mind, the scientific team examined the intestinal tract of naked mole rats and compared their intestinal ASCs (Lgr5+) with those of mice and humans. Study co-author Dustin J. Penn from the Vetmeduni's KLIVV said: “In vivo, we found an expanded pool of Lgr5+ cells in naked mole-rats. These cells exhibit slower division rates compared to those of wild house mice, specifically at the crypt base (Lgr5+CBC), but have a similar turnover to human Lgr5+CBC cells. Instead of entering quiescence (G0), naked mole rat Lgr5+CBC cells reduce their division rates by prolonging the G1 and/or G2 phases of the cell cycle.”

In addition, the researchers observed a higher proportion of differentiated cells in naked mole rats, which provide the intestinal mucosa with better protection and function. “The intestinal mucosa of naked mole rats is able to efficiently detect any chemical imbalance in the intestinal environment and trigger a robust pro-apoptotic, anti-proliferative response within the stem/progenitor cell zone,” explains study co-author Dustin J. Penn from the KLIVV at the Vetmeduni.

Less cancer: Evolutionary adaptations reduce the incidence of age-related diseases

Their study characterizing the intestinal tract of naked mole rats adds to the growing body of evidence that these remarkable animals have evolved unique adaptations that enable long-term maintenance of tissue homeostasis and, as a secondary consequence, reduce the incidence of age-related diseases such as cancer. The development of a greater reserve of ASC in all tissue types in naked mole rats facilitates efficient maintenance of the tissue in an environment of high oxidative and mechanical stress, reduces the likelihood of fixation of deleterious mutations due to increased selection against deleterious variants, and slows the clonal expansion that occurs in aging can be observed. The lower ASC division rates in the gut of naked mole-rats – as in humans – also likely prevent proliferative exhaustion of ASCs, which is necessary for a longer life expectancy.

The article “Adult stem cell activity in naked mole rats for long-term tissue maintenance” by Shamir Montazid, Sheila Bandyopadhyay, Daniel W. Hart, NanGao, Brian Johnson, Sri G. Thrumurthy, Dustin J. Penn, Bettina Wernisch, Mukesh Bansal , Philipp M. Altrock, Fabian Rost, Patrycja Gazinska, Piotr Ziolkowski, Bu'Hussain Hayee, Yue Liu, Jiangmeng Han, Annamaria Tessitore, Jana Koth, Walter F. Bodmer, James E. East, Nigel C. Bennett, Ian Tomlinson and Shazia Irshad was published in Nature Communications.

Scientific Article

Dogs often show sympathy and joy by wagging their tails. But how did the rhythmic back and forth of the dog's tail develop? And is tail wagging really always a synonym of joy?  The answer is anything but clear. Tail wagging is a conspicuous but scientifically elusive behaviour. Until now, different scientific meanings have been attributed to it, leading to fragmentary and contradictory answers. An international review study just published in the journal Biology Letters with the participation of the Konrad Lorenz Institute of Ethology (KLIVV) at the University of Veterinary Medicine Vienna highlights this problem - and at the same time provides new explanatory approaches to finally develop a structured theoretical framework.

In their review, the study authors summarise the existing research on the mechanisms, development, evolution and function of tail wagging in domestic dogs (Canis familiaris) and show where the results converge or diverge. As a solution to this discrepancy, the scientists suggest investigating this behaviour from its evolutionary roots.

Two new hypotheses to explain how tail-wagging evolved

The researchers put forward two hypotheses to explain its more frequent occurrence compared to other closely related dog species (canids) such as wolves. According to this hypothesis, tail wagging could have evolved in two ways during the domestication process: either as a by-product of selection for other traits, such as docility, or as a trait directly selected for by humans who are attracted to repetitive and rhythmic movements.

Giulia Cimarelli from the Domestication Lab (KLIVV) at Vetmeduni and her colleagues see this as an important starting point for new studies: "We propose to test these hypotheses through neurocognitive studies in both dogs and humans and thus shed light not only on a key behaviour of dogs, but also on the evolutionary history of characteristic human traits, such as our ability to perceive and produce rhythmic behaviours.."

A prime example of dog-human communication

Domestic dogs are the most widespread carnivores in the world: with an estimated population of one billion, they are present almost everywhere humans live. Due to their close cohabitation, humans interact directly with dogs in many contexts and must use various signals to communicate effectively. In particular, the position and wagging of the tail provide easily observable information that humans use to understand the internal state of the dog. "Tail wagging is probably one of the most distinctive animal behaviours that humans can observe," says Giulia Cimarelli.

The article "Why do dogs wag their tails?" by Silvia Leonetti, Giulia Cimarelli, Taylor A. Hersh and Andrea Ravignani was published in "Biology letters". 

Wissenschaftlicher Artikel

Successful courtship is a question of practice, and the most successful aren’t necessarily the biggest show-offs – alternative flirting strategies are just as promising. Subtle, demure behaviour, such as coyness, arouses curiosity and can increase the interest in a potential sexual partner. This sounds very human, but a recent study conducted by the Konrad Lorenz Institute for Ethology at the University of Veterinary Medicine Vienna analysed this behaviour in avian courtship. The review was published in the British scientific journal Proceedings of the Royal Society B.

The three researchers analysed previously published studies on avian courtship and suggest that sexual selection research has been dominated by the notion that the strongest, most impressive and most extravagant courtship displays will lead to the highest success in mate selection – in other words, that the displays best reflect the quality of the courter.

Subtle trumps vigorous

However, as the researchers note, courtship displays are often structured temporally and contain different elements with varying degrees of intensity and conspicuousness. “For example, highly intense movements are often coupled with more subtle components such as static postures or hiding displays,” as Thomas MacGillavry explains. The researchers refer to such subtle display traits as “coy”, as they involve the withholding of information about maximal display capabilities.

Three hypotheses for the success of coy courtship behaviour

The researchers examined the role of intensity variation within temporally dynamic displays and discuss three hypotheses for the evolution of coy courtship behaviours. Giovanni Spezie explains: “We first review the threat reduction hypothesis, which points to sexual coercion and sexual autonomy as important facets of sexual selection. We then suggest that variation in display magnitude exploits pre-existing perceptual biases for temporal contrast.” As a third hypothesis, the researchers propose that withholding information may leverage the receivers’ predisposition for filling in the missing gaps – a phenomenon they call “curiosity bias” – with the goal of arousing curiosity in potential sexual partners.

New insights for a better understanding of courtship behaviour

“Much like human music or theatre, courtship displays may constitute true performances in their own right, where different elements interact to entice, build suspense, surprise and excite the intended audience. The way in which such performances unfold over time represents a promising and novel direction for studies of courtship behaviour,” says Leonida Fusani. The underrepresentation of such aspects is due to the fact that behavioural research tends to break down behaviour into its components and does not look at it as a whole, the researchers say. Such an analysis, however, may not correspond to the actual interactions that occur during these kinds of courtship displays.

The article “When less is more: coy display behaviours and the temporal dynamics of animal courtship” by Thomas MacGillavry, Giovanni Spezie and Leonida Fusani was published in Proceedings of the Royal Society B.

Scientific article

Photos: Dominic Chaplin