The circular wings display of Victoria’s riflebird – a bird of paradise species found in Australia – is a fascinating sight, since it at first glance looks more like the flower of an exotic plant than what we know as a bird. As the researchers of a study led by the University of Veterinary Medicine Vienna have now been able to prove for the first time, there is a very special physical ability behind this unusual courtship behavior. This ability distinguishes the riflebirds from all other birds and is involved in both visual and acoustic features of display. An attractive and complex combination that potential partners will find hard to resist.

Humans aren’t the only species in which males show off for females. From a scientific perspective, sexual selection through female choice has driven the evolution of some of the most sophisticated signaling behaviors in animals. These displays often require specialized morphological adaptations and can involve signals in multiple sensory modalities. In addition, visual and acoustic signals are often precisely choreographed in temporally structured courtship displays.

Shapeshifters: Unique acrobatics enable extraordinary visual effects

The riflebirds (genus Ptiloris) are quite a remarkable group of birds. The researchers of the study, which has just been published in the “Biological Journal of the Linnean Society”, have now been able to demonstrate for the first time that these birds of paradise achieve their remarkable courtship postures by hyperextending the wrist joint – something quite normal for humans, but previously unknown in birds, which lock the wrist in place to allow more stability during flight. “This goes far beyond the maximum extension of the wrist of all other known birds,” says the first author of the study, Thomas MacGillavry from the Konrad Lorenz Institute of Ethology (KLIVV) at Vetmeduni, emphasizing the uniqueness of this ability.

Sound and vision: an impressive multimedia spectacle with an ingenious trick

But the fascinating findings go even further, as the senior author of the study Leonida Fusani, head of KLIVV, explains: “Using video collected in the field, we then show that this hypermobility is required for a sonation [the production of sound not involving the vocal organs] unique to riflebirds, and find that the yellow interior of the mouth is displayed in the dynamic phase of display.” As a result, the sonation cannot be produced when the yellow inside of the mouth is flashed open, creating a unique kind of tradeoff.

Behind the beautiful façade: just the one thing in the head

Finally, the researchers used a large morphometric dataset to describe patterns of sexual dimorphism in wing length in different bird of paradise species to look for evidence of sexual selection for large and structurally modified wings used in courtship displays, particularly in the riflebirds.

With the sum of their findings, the researchers took a major step forward in what we know about riflebird displays - despite the fact that the general patterns of displaying behavior of these birds are well described in the literature. “Our study has nonetheless revealed that these performances are much more mechanically intricate than previously anticipated, and highlights how mate choice can drive the evolution of extreme behavioural and morphological phenotypes that function exclusively for sexual display.” said Thomas MacGillavry and Leonida Fusani.

The article „The mechanics of male courtship display behaviour in the Ptiloris riflebirds (Aves: Paradisaeidae)“ by Thomas MacGillavry, Clifford B. Frith and Leonida Fusani was published in „Biological Journal of the Linnean Society“.


Scientific article

Aquarium enthusiasts are familiar with the East African cichlid Neolamprologus pulcher as the Princess of Burundi. Scientifically, it is often used in animal models to study behaviour - the University of Veterinary Medicine Vienna is one of the world's leading institutions in this field. A research group led by the Konrad Lorenz Institute of Ethology (KLIVV) has now investigated how the blockade of glucocorticoid receptors affects stress and behaviour. The results of the study have been published in the scientific journal “Physiology & Behavior”.

The researchers investigated the question of whether the so-called stress axis is associated with behavioural flexibility in the social cichlid Neolamprologus pulcher. To this end, the scientists pharmacologically blocked the glucocorticoid receptors (GR) of adult N. pulcher by administering a GR antagonist in a minimally invasive manner. First author Stefan Fischer from the Konrad Lorenz Institute of Ethology (KLIVV) at the Vetmeduni explains the background to the study: “Glucocorticoid receptors (GR) are important mediators of the stress response. GR blockade prevents recovery after a stressful event, which we hypothesized would impair behavioural flexibility.” After administration of the GR antagonist, the fish were repeatedly exposed to a predator and their behavioural flexibility was tested using a detour task. The fish had to find a new, longer route to a shelter when the shortest route was blocked.

GR blockage altered fear perception and reduced behavioural flexibility

While the time to find a shelter did not differ between the fish given a GR antagonist and a control group without GR antagonists, the fish with GR blockade showed more failed attempts at the detour tasks than the control fish. In addition, the poor performance in the detour tasks was associated with an increase in fear-related behaviours. “This suggests that blocking GR alters the perception of fear and leads to reduced behavioural flexibility. Our results therefore demonstrate a possible link between the ability to recover from stressors and behavioural flexibility in N. pulcher, potentially impacting effective and adaptive coping with changes in the environment,” said co-author Leonida Fusani from KLIVV.

An exciting combination: How stress responses affect behavioral flexibility

Behavioural flexibility plays an important role in the way animals cope with novel situations, and physiological stress responses are adaptive and highly efficient mechanisms for coping with unpredictable events. “To better understand how stress affects behavioural flexibility in a natural context, we therefore performed direct manipulations of the stress response and conducted cognitive tests in ecologically relevant contexts, whereas previous studies were mostly conducted only under laboratory conditions,” emphasizes Stefan Fischer.

The artikel „Does the stress axis mediate behavioural flexibility in a social cichlid, Neolamprologus pulcher?“ by Stefan Fischer, Zala Ferlinc, Katharina Hirschenhauser, Barbara Taborsky, Leonida Fusani and Sabine Tebbich was published in „Physiology & Behavior“.


Scientific article

Bird migrations are one of the most extreme and energy-consuming strategies that have evolved in the animal kingdom. Against this background, seasonal migrations in birds are characterized by a rapid physiological and metabolic transformation. This includes the considerable accumulation of fat stores and an increase in nocturnal activity. However, the role played by the molecular basis and adaptations of the brain in this process was hardly known until now. An international study led by Vetmeduni now sheds light on this. The paper was published in Scientific Reports.

In their study, the researchers exposed quails (Coturnix coturnix) to controlled changes in day length in order to simulate autumn migration to the south. They then blocked the photoperiod until the birds entered the non-migratory hibernation phase.

Up-regulation of gene expression networks during bird migration

Now, the research team performed RNA sequencing of selected brain samples (hypothalamus) taken from birds at a standardized time during the night when agitation was highest and body mass was at its peak. “We found that the migratory state was associated with an upregulation of a few but functionally well-defined gene expression networks involved in fat transport, protein and carbohydrate metabolism,” says Valeria Marasco, first author of the study and Assistant Professor of Wildlife Physiology at the Research Institute of Wildlife Ecology at Vetmeduni.

Gene expression follows the time of day with a maximum during the night

Further analyses focusing on candidate genes (apolipoprotein H [APOH], lysosomal-associated membrane protein-2 [LAMP2]) from samples collected during the day or night from the entire study population revealed differences in the expression of these genes depending on the time of day, with the highest expression levels found in samples collected at night from migratory birds. “We also found clear evidence that the expression of APOH was positively associated with nocturnal activity in the migratory birds. However, no such association was seen in the control group of non-migratory birds or in the migratory birds sampled during the day,” explain study authors Steve Smith and Leonida Fusani from the Konrad Lorenz Institute of Ethology at Vetmeduni (KLIVV). 

Expression of apolipoproteins as the basis of nocturnal migratory movements

According to the scientists, the results provide new experimental evidence that hypothalamic changes in the expression of apolipoproteins, which regulate the circulating transport of lipids, are likely to be important regulatory activators of nocturnal migratory movements. “We anticipate that our study will pave the way for deeper functional investigations of the seasonal physiological reorganization underlying the development of the migratory phenotype,” says Valeria Marasco. “Understanding the neurological and molecular substrates by which highly seasonal species such as migratory and hibernating vertebrates can adapt their energy metabolism on a seasonal and daily basis is key if we want to understand the impact of ongoing climatic challenges on the life history and fitness of organisms as we enter the disruptive phases of the Anthropocene,” concludes Marasco.

The article „Brain gene expression reveals pathways underlying nocturnal migratory restlessness“ by Valeria Marasco, Leonida Fusani, Patricia Haubensak, Gianni Pola and Steve Smith was published in „Scientific Reports“.


Scientific Article

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