Skip to main content

VetmedTalk „Grüne Lungen“ (Green lungs). People and animals in forest ecosystems

 (Talk in German)

VetmedTalk: Heute verstehen. Morgen verändern.

 

12 December 2022 | 5-6 p.m. | Online 

Sometimes you can't see the forest for the trees: Countless details block the view of the big picture. With this VetmedTalk, the University of Veterinary Medicine, Vienna, together with the experts from the Donauauen National Park and the Austrian Federal Forests, wants to offer a comprehensive overview of the special features of the forest habitat. For a healthy future for animals and humans, we need a healthy forest.

Austria is a densely wooded country: 3.5 billion trees cover almost 50 percent of the national area and form a diverse habitat for a wide variety of animals. Deer and rabbits, foxes and hedgehogs, but also many birds, insects, amphibians and reptiles make the forests a unique ecosystem. The VetmedTalk "Green Lungs" presents exciting research projects from veterinary medicine and examines how the health of animals and the health of humans are related through the forest habitat.

Forests are essential for us humans. They produce oxygen for our air, wood for our furniture, store our drinking water, prevent floods and protect against mudslides and avalanches. We use the "green lungs" in our free time as a place to relax, and as a huge carbon store, they are also an important instrument in climate protection. At the same time, the forest is a habitat for countless animal species, flora and fauna in the forest are essential for a healthy environment. Nevertheless, we humans have a massive impact on the life of these forest ecosystems through climate change and intensive forest use.

How can humans and animals coexist and thrive in the forest? And what can veterinary medicine contribute to climate protection and biodiversity?

In 2022, the Vetmeduni will focus on communication on "Life on land", UN Sustainable Development Goal No. 15, with a special habitat focus each quarter. It started with air, followed by fresh water and meadows , and the forest ecosystem now concludes the series. The last VetmedTalk of this year is about the status quo of our forest dwellers and how we can protect their habitat. Science communicator Bernhard Weingartner and his guests will answer questions from the online audience.

Experts

  • Claudia Bieber, Research Institute of Wildlife Ecology, Vetmeduni
  • Edith Klauser, Nationalpark Donauauen
  • Alexandra Wieshaider, Austrian Federal Forests
  • Richard Zink, Konrad Lorenz Institute of Ethology, Vetmeduni

Moderation

  • Bernhard Weingartner, Science communicator and initiator of the Science Slam Austria

Stream

Live online stream at www.vetmeduni.ac.at/vetmedtalk-wald

 

2022-11-17

The sex lives of birds

Banding together may pay off for subordinate males

Male spotted bowerbirds (Ptilonorhynchus maculatus) build and defend a structure of sticks and straw - the bower. They decorate these nests with colourful objects to attract mates during the breeding season. Certain non-resident subordinate males are tolerated by resident males in their bowers over multiple breeding seasons. Previous research has shown that these male coalitions bring indirect benefits to subordinate males. So far, however, it has been unclear whether lower-ranking males also have direct advantages. A current study by the Konrad Lorenz Institute of Ethology of the Vetmeduni shows for the first time that in rare cases the lower-ranking birds benefit directly from copulation opportunities.

The study documents four cases of sneaky matings or mating attempts by subordinate males. The cases were observed in the bowers of spotted bowerbirds during the 2018 breeding season. Several non-resident males disrupted ongoing copulations between the bower-owner and a receptive female, and these events were followed by vigorous aggressive interactions. "These observations shed new light on same-sex social dynamics in bowerbirds and support the hypothesis that subordinate males are sexually mature individuals who occasionally gain access to females while visiting established bowers," said study first author Giovanni Spezie of the Konrad Lorenz Institute of Ethology at the Vetmeduni.

First observation of extremely rare events

The rarity of the events now observed is remarkable. Extensive observations have been made on spotted bowerbirds for several decades - but so far, none of the observed copulation events has been documented. Study lead author Leonida Fusani from the Konrad Lorenz Institute of Ethology at Vetmeduni: “The fact that we were able to record at least four independent observations in different individuals strongly indicates that sneaky copulations are not an isolated and abnormal behaviour. Rather, it is a behavioural pattern or alternative reproductive strategy used by subordinate males.”

Beta profits from Alpha – male coalitions are profitable

Male-male coalitions have so far been observed particularly in birds such as manakins, grouse, peacocks, wild turkeys and bowerbirds. A common feature of most courtship coalitions is that a dominant "alpha" male accounts for all or most copulations, while subordinate "beta" males abstain from breeding and have no—or very limited—access to mates. Sacrificing reproductive potential for a male association may seem paradoxical, but it has direct and indirect benefits for the subordinate males. The animals benefit indirectly, for example, from taking over the position of the alpha male after his death or from learning behaviour that is important for successful mating from him. As it turns out, they also derive direct benefits from clandestine mating with females.

The article "Sneaky copulations by subordinate males suggest direct fitness benefits from male-male associations in spotted bowerbirds (Ptilonorhynchus maculatus)“ by Giovanni Spezie and Leonida Fusani was published in „Ethology“.
 

Scientific article

 

2022-11-30

 

 

 

 

 

 

 

 

 

Measuring brain size in birds: Which parameters are best?

Do bigger heads necessarily mean bigger brains? The study of brain size (as a proxy for cognitive ability) is rather difficult in wild animals, and scientists have tried to find ways to measure brain size without harming the animals. Head size has been used in the past and seems to work for some species – but not for all. In a study on quails by Vetmeduni scientists and researchers from Poznań University of Life Sciences, Poland, researchers found that it was head height, rather than overall head volume was a better predictor of brain size, However, it turns out that every species is different and needs to be assessed separately.

At least in part, the brain’s capacity to process cognitive processes depends on the mass of neural tissue involved – the more tissue, the more information can be processed. In fact, studies often find a positive relationship between brain size and cognitive performance. However, the majority of these studies are based on comparisons between different species. A growing number of scientists is now trying to understand how more subtle differences between individuals of the same species are related to their cognitive skills, which is often a big challenge when studying animals in nature. To do so researchers require techniques that do not interrupt the natural life cycle of wild birds.

A first study of barn swallows proposed to use external head measurements, which require handling but not the sacrifice of the individual bird, as an accurate approximation for brain mass.

A team of researchers from the Konrad Lorenz Institute of Ethology (KLIVV) of the Vetmeduni, together with researchers from Poznań University, Poland employed this method for the first time in a small Galliform, the Common Quail. They measured both the external head dimensions of the birds as well as the weight of their brains and tested how well these two measurements were related to each other.

Head height is crucial

Although the scientists found that these measurements were correlated, the correlation values were not very strong. This means that external head measurements really cannot be used reliably to predict an individual’s brain mass with high confidence. Instead, the best predictor of brain mass was not head volume per se, as was previously shown in barn swallows, but the height of the head alone.

“Our results show that the model that explained the highest proportion of variance in brain mass contained only one head measurement, the head height,” says Valeria Marasco, one of the two first authors of the study. “Nevertheless in our study species, the Common quail, this measure explained only a small proportion of the variance in brain mass of different birds. Studies on other species have found a much more significant effect of one or the other variable.”

It is likely, therefore, that other factors also explain the variation. “For example, average beak lengths in different species could influence head measurements,” says Joanna Białas, joint first author of the study. Interestingly, brain size was not at all related to body mass or length of the bird overall. Brain size has evolved from other aspects of an animal´s morphology.

The researchers recommend validating the original method of external head measurements in each avian species before making assumptions on how these measurements might be related to brain size and cognitive performance. More studies across diverse bird species are also needed to elucidate potential relationships between relative brain size, body parameters, and sex.
 

The article “Are external head measurements a reliable predictor of brain size in the Common Quail (Coturnix coturnix)?” by Joanna T. Białas, Valeria Marasco, Leonida Fusani, Gianni Pola, and Marcin Tobółka was published in the Canadian Journal of Zoology.

Scientific article

2022-11-17

 

How sex differences affect poison frog spatial behaviour

Sex differences in vertebrate spatial abilities are typically interpreted under the adaptive specialization hypothesis, which posits that male reproductive success is associated with larger home ranges and better navigation skills. The androgen spillover hypothesis refutes that improved male spatial performance could be a by-product of higher androgen levels. Animal groups that include species for which females are expected to outperform males based on life history traits are key to disentangling these hypotheses.

An international team of researchers now investigated the connection between sex differences in reproductive strategies, spatial behaviour and androgen levels in three species of poison frogs. To do this, they tracked individuals in their natural environments to show that different parental roles shape sex differences in space use, with the sex performing parental responsibilities showing wider movements.

After that, they moved frogs from their home ranges and relocated them to a new area to test their navigation performance. The researchers found that the caring sex outperformed the non-caring sex in only one out of three species. In addition, males of all species displayed more exploratory behaviour than females, with androgen levels correlating with exploratory behaviour and targeting accuracy.

Overall, the researchers were able to show that reproductive strategies of poison frogs shape their movement patterns, but not necessarily their navigational performance. This research suggests that the prevailing adaptive hypotheses provide only an incomplete explanation for sex differences in spatial abilities.

The article "Contrasting parental roles shape sex differences in poison frog space use but not navigational performance" by Andrius Pašukonis, Shirley Jennifer Serrano-Rojas, Marie-Therese Fischer, Matthias-Claudio Loretto, Daniel A Shaykevich, Bibiana Rojas, Max Ringler, Alexandre B Roland, Alejandro Marcillo-Lara, Eva Ringler, Camilo Rodríguez, Luis A Coloma, and Lauren A O'Connell was published in eLife .

Scientific article

2022-11-17

Feeling safe with mommy

A mother´s stress during pregnancy can affect physiological and behavioural individual characteristics of their offspring in many species.  However, the environment and care of offspring after birth can modulate these characteristics. There have been many studies about the effects of maternal care in mammal species, but there has been surprisingly little research into the same effect in bird species.

An international team of scientists studied the extent to which prenatal maternal stress in Japanese quails (Coturnix japonica), and the emotional response associated with it, can be modulated by the presence of an adoptive mother during the chicks´ development. For this experimental study, they observed chicks whose mothers had experienced a socially unstable environment during laying and egg production, because social instability during egg laying and brooding is known to increase the emotional reactivity of the mothers´ offspring.

To assess the effect of mothering, the researchers raised the chicks either with or without an adoptive quail mother. They found out that those chicks who were raised with a mother, were less anxious, for example in the presence of novel objects or when being separated from their mates.

These results clearly highlight the fundamental importance of a mother´s presence in modulating stressful events before and after birth, even in a precocial species (in which the young are relatively mature and mobile from the moment of birth or hatching), such as quails. It may be a key mechanism driving phenotypic plasticity (i.e. all types of environmentally induced changes) in wild populations.

The article “The presence of a mother counteracts prenatal stress in a precocial bird” by C. Houdelier, M. Charrier, O. Le Bot, N. Aigueperse, V. Marasco, and S. Lumineau was published in Animal Behaviour.

Scientific article

2022-10-27

Follow your nose: songbirds smell their way back home

Sight, smell or both? How birds find their way back to a feeding site was the subject of a recently published study conducted by a team of researchers at the University of Veterinary Medicine Vienna. The researchers observed great tits and were able to show that olfaction is an essential tool for finding one's way, even in familiar surroundings. These findings highlight that in birds the sense of smell is indeed more important for orientation than previously thought.

The great tit (Parus major) is a common songbird with a wide distribution range. It is a welcome guest at birdfeeders in winter and therefore focus of a  recently published study. A team of scientists tested whether great tits use odours from the environment to find their way back to feeding sites. The researchers captured the birds and in some of the individuals, they briefly dampened their sense of smell by rinsing their noses with zinc sulfate. Afterwards, all birds were released - some in the immediate vicinity and another subset of the animals was let go at a distance of 1.5 km.

Great tits with unaltered olfactory capacity returned more quickly to their home range

Both, the great tits with a reduced sense of smell and those with a normal sense of smell found their way back to the feeding sites. "This result did not surprise us at first, as we deliberately released the birds within their familiar environment," explains study first author Katharina Mahr from the Vetmeduni's Konrad Lorenz Institute of Ethology. "It is interesting, however, that birds with a diminished sense of smell needed significantly more time to return. This effect is pronounced when the birds were released at a greater distance. Our results indicate that odours serve as an important source of information for orientation in a familiar environment, despite the existence of visual cues."

A good sense of smell helps to optimise foraging efficiency

According to the researchers, certain smells and scent cues in the familiar environment could serve as a reliable source of information for finding one's way around. “Similar results have already been obtained for migratory birds. But especially for species such as great tits, which often overwinter in breeding areas, orientation and navigation by means of smell could help to optimize foraging in times with little food supply, for example in the winter,” says last author Herbert Hoi, also from the Vetmeduni’s Konrad Lorenz Institute of Ethology. According to Hoi the results of the study strongly emphasise that olfaction might be of greater importance for the orientation of avian species than previously thought, thereby contributing to the understanding of the functional contexts of smell in avian life.

Chemistry in the air

Airborne chemicals function as sensory cues for many organisms, and their use in navigation may be one of the most important evolutionary mechanisms that explains the development of olfaction in animals. Despite solid evidence for the importance of olfaction in avian life – for example, in foraging or mating – the importance of chemical cues for avian orientation remains largely debated. Olfaction in songbirds is, despite their remarkable orientation skills, surprisingly understudied.

The article "Songbirds use scent cues to relocate to feeding sites after displacement: An experiment in great tits (Parus major)“ by Katharina Mahr, Linda Nowack, Felix Knauer, and Herbert Hoi was published in „Frontiers in Ecology and Evolution“.

 

Scientific article

 

2022-09-09

Global change affects the social behaviour of poison dart frogs

What effects do global environmental and climate changes have on social behaviour - this question is being investigated in a current study by the Konrad Lorenz Institute of Ethology (KLIVV) at the Vetmeduni under the leadership of Lia Schlippe Justicia in Bibiana Rojas' research group, using poison dart frogs that live in the South American rainforests. Poison dart frogs are affected by a number of changes in their habitat. The researchers therefore expect a significant change in social behaviour, including increased levels of aggression and parental care challenges.

Human-caused environmental changes include habitat loss and fragmentation, spread of novel pathogens and diseases, pollution, and climate change. In the tropics, too, these disturbances affect a wide variety of species. The resulting interactions challenge the social and sexual behaviour of animals and their interaction with the environment.

Amphibians such as poison dart frogs (Dendrobatoidea) exhibit a wide range of social and sexual behaviours. According to the researchers, this makes them a useful model for understanding the potential adaptations of animals exposed to rapid anthropogenic environmental changes and their impacts on species.

Challenges for young and parent animals

The scientists assume that young animals and larvae are particularly threatened by environmental changes. “More irregular rainfall and higher temperatures limit the availability and diversity of larval nurseries while increasing the likelihood of desiccation. In order to compensate for these negative effects, parent animals will spend more time tending to clutches and taking tadpoles to less endangered rearing sites," says lead author Lia Schlippe Justicia from the Konrad Lorenz Institute of Ethology (KLIVV) at the Vetmeduni.

Higher aggression and increased cannibalism

In addition, the experts expect more frequent cannibalism among young animals and generally higher rates of aggression in adults due to a limitation in resources and territories and human-caused noise. The last author of the study, Bibiana Rojas from the KLIVV says, "Changed environmental conditions resulting from small-scale deforestation or increased noise pollution can disrupt important communication processes, such as courtship or partner selection, since the call of the males is harder to hear and the recognizability of the partner therefore reduced."

Der Artikel „Poison frog social behaviour under global change: potential impacts and future challenges“ von Lia Schlippe Justicia, Chloe A. Fouilloux und Bibiana Rojas wurde in „Acta Ethologica“ in der Sonderausgabe "Impact of global change on social interactions: Auswirkungen auf Ökologie und Fitness" veröffentlicht.

Environmental changes, social behaviour and reproduction

Anthropogenic environmental changes have a major impact on the interactions of organisms with each other and with their environment. Changing behaviour is often the first reaction. The nature of this behaviour can determine how or whether organisms adapt. The survival of the offspring is of particular importance. According to the researchers, the analysis of behavioural and environmental changes through future studies will make an important contribution to better assessing the effects on different species and populations.

Scientific article

2022-09-07

 

Together we can – Courtship coalitions in bowerbirds

In many animal species there is strong competition among males to find a willing female partner. For this reason, elaborate courtship rituals have evolved, notably in many bird species who often perform dances that show off their strength and beauty, or, as in the case of bowerbirds, even create a special “stage” to charm females. But despite strong selective pressures inherent in competition for mates, in some species males accept same-sex visitors at display arenas.

Bowerbirds perform courtship dances on elaborate display structures — known as bowers — that are built and defended by one resident male. Several reports have suggested that bower owners tolerate the presence of so-called ‘subordinate’ male visitors at their display arenas, though their role has received little attention. It has been suggested that subordinate males may learn the skills required for successful sexual signalling via prolonged social interactions at adults’ arenas, but it remains unclear whether courtship proficiency changes with experience. It may also be that subordinates actively contribute to enhancing the resident male’s mating success, yet little is known about whether this is the case.

In a study, scientists from the Konrad Lorenz Institute of Ethology and the University of Vienna investigated male-male associations in wild spotted bowerbirds (Ptilonorhynchus maculatus). They first sought to determine whether courtship behaviour differs based on bower ownership status. They then examined whether social interactions between bower owners and subordinate males may qualify as courtship coalitions.

Rudimentary courtship coalitions

Their analysis did not reveal differences between subordinate males and bower owners in specific parameters of courtship related to behavioural flexibility, but they found evidence that male-male associations in spotted bowerbirds may actually be an example of rudimentary courtship coalitions. The subordinate males may in fact be helping the bower owner, even if not by displaying cooperatively or by actively defending the arena from destruction by neighbouring marauders, by sheer strength in numbers that would discourage other males’ attempts to destroy the arenas. The magnitude of subordinate attendance correlated with owner males’ mating success (number of copulations). The researchers also found that male coalitions are stable in subsequent years. The findings point to the possibility that subordinate males in this species may not associate with bower owners as part of a form of apprenticeship, but rather may get other benefits from establishing long-term partnerships. One hypothesis is that saturation of suitable display sites may force sexually mature subordinate males to “queue” in order to gain ownership of established arenas when these become available. Moreover, the male partnerships may allow subordinate males to establish dominance hierarchies with surrounding males and gain social competence.

In the study the researchers also observed a few occurrences of subordinate males copulating or attempting to. Thus subordinate males may also obtain direct fitness benefits from such courtship coalitions — i.e. occasional access to females.

This study provides novel information about social dynamics among male bowerbirds, and further insights into the evolution of coalitionary behaviour in male displays. Further study is needed, for example to find out how these coalitions are formed, and whether subordinate males selectively choose their model, or whether bower owners tolerate some subordinate males and repel others.

The article “Male–male associations in spotted bowerbirds (Ptilonorhynchus maculatus) exhibit attributes of courtship coalitions” by Giovanni Spezie and Leonida Fusani was published in Behavioral Ecology and Sociobiology.

Scientific paper

2022-08-29