Living walls boost biodiversity by providing safe spaces for urban wildlife
University of Plymouth
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The living wall constructed on the University of Plymouth's Sustainability Hub was one of three examined for the study, with researchers using a range of observation techniques and acoustic monitoring surveys to assess the different animal species frequenting it
view moreCredit: University of Plymouth
Living walls – structures housing flowers and plants fitted to the outside of new and old buildings – can significantly enhance the biodiversity within urban environments, a new study has shown.
The research monitored activity involving pollinating insects, spiders, soil invertebrates, birds and bats at three locations spread across the city centre and outskirts of Plymouth.
Over three survey periods, hundreds of creatures were observed including 12 different types of bees, hoverflies and other pollinators as well 19 types of soil invertebrates and 12 species of spiders.
There were also 32 bird species recorded across the locations, with three species – house sparrows, blackbirds and robins – observed nesting within the living walls.
Living walls with plants in soil attracted more wildlife than those with plants grown in artificial substrates, and the type of plant was also important with ivy, Mexican daisy and honeysuckle attracting the highest number of pollinator species.
Writing in the Journal of Urban Science, researchers say their findings indicate that appropriately designed soil-based living wall systems can deliver meaningful urban biodiversity benefits when integrated with strategic plant selection.
With the world’s cities expanding at an ever-increasing rate, with an estimated 68% of the world's population projected to live in urban areas by 2050, they believe living walls could help to preserve biodiversity at a time when it is increasingly being lost.
The project involved scientists and students from the University of Plymouth’s School of Geography, Earth and Environmental Sciences and School of Biological and Marine Sciences.
They used a range of observation techniques and acoustic monitoring surveys to assess the different animal species frequenting the living walls at the University’s Sustainability Hub, the Genesis Building on Union Street and in the Sherford new town development.
Dr Paul Lunt, Associate Professor in Environmental Science at the University of Plymouth and the new study’s lead author, said: “We’re in the middle of a global biodiversity crisis where wild species are increasingly being threatened by the changing climate and habitat loss. We need to do everything we can to support our wildlife, and it is one of the reasons why living walls are becoming an increasingly visible feature of UK urban design. Our work provides one of the clearest assessments to date of their biodiversity benefits, as well as a policy challenge with current legislation meaning their ecological contributions are being undervalued in planning assessments. Based on our research, we feel there is a case for revisiting that if we are to fully realise the extent to which living walls can benefit our urban flora and fauna.”
The University has been advocating for the greater use of living walls – and other environmental building techniques – for many years, with the one analysed in this research added to the Sustainability Hub on its main campus in 2019.
Since then, it has been pursuing research to monitor the structures’ effectiveness, including research published in 2021 which demonstrated that retrofitting an existing masonry cavity walled building with a green or living wall can reduce the amount of heat lost through its structure by more than 30%.
Living walls boost biodiversity by providing safe spaces for urban wildlife [VIDEO]
Dr Paul Lunt, Associate Professor in Environmental Science at the University of Plymouth, talks about new research into living walls and the benefits they can have for biodiversity in urban environments.
Credit
University of Plymouth
Journal
Urban Science
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Biodiversity Performance of Living Wall Systems in Urban Environments: A UK Case Study of Plant Selection and Substrate Effects on Multi-Taxa Communities
Aging zoo animals threaten long-term species conservation goals of modern zoos
New method from Goethe University Frankfurt reveals demographic risks in zoo mammal populations
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The analysis of Meireles and colleagues shows that reproduction, as shown here in the endangered Grévy's zebra (Equus grevyi), is on the decrease across zoo mammal populations.
view moreCredit: Tim Benz/Zoo Zürich
FRANKFURT/ZURICH. Images of newborn zoo animals regularly attract public attention – yet the impression of cute baby animals is deceptive. Across many species, births are becoming rarer while populations grow steadily older- a development documented by an international study led by the University of Zurich (Switzerland) in collaboration with Goethe University Frankfurt (Germany), Aarhus University (Denmark), Zoo Zurich (Switzerland) and Copenhagen Zoo (Denmark).
For the study, the researchers analyzed the demographic data from a total of 774 zoo mammal populations (361 in North America, 413 in Europe) covering the period from 1970 to 2023. The analysis draws on the global “Species360” database, used by more than 1,200 institutions worldwide. The database records detailed life-history information for individual animals, including age, sex, ancestry, origin, and reproductive status, enabling a systematic assessment of zoo population structures over several decades.
Distorted Age Pyramids
To evaluate population stability, the team examined age pyramids – a standard demographic tool that illustrates the distribution of age groups within a population. Researchers at Goethe University Frankfurt developed a new method for the automated classification of these population pyramids, allowing demographic patterns to be compared across species and regions with greater precision. This approach translates complex population structures into standardized forms – such as pyramids, diamonds, or columns – each associated with different levels of demographic resilience. Prof. Paul Dierkes of Goethe University Frankfurt, who played a key role in developing the method, explains: “Especially for zoos and species conservation, this new methodological approach and the results based on it open up possibilities for clearly communicating demographic developments and making informed decisions.”
But what do the different basic shapes tell us? A classic pyramid shape—with many young and reproductive individuals at the base and progressively fewer older animals—indicates a stable and resilient population. Such populations are better equipped to withstand unexpected shocks, including disease outbreaks. The study shows, however, that an increasing number of zoo populations now display diamond- or column-shaped profiles, characterized by relatively few young animals and a high proportion of older individuals. These structures are considered demographically fragile.
The study also shows that, at the same time, the proportion of actively reproducing females has declined sharply: by 49 percent in North American populations and by 68 percent in European populations. In some cases, populations no longer include any females capable of reproduction. Beyond reducing offspring numbers, this trend can disrupt social structures in many mammal species. Reproduction and rearing young animals are fundamental behavioral components and key elements of species-appropriate husbandry.
Species Conservation Goals at Risk
This development is concerning to the researchers and could threaten the species conservation work of modern zoos. Zoos are internationally recognized partners in global species conservation, particularly through the maintenance of reserve populations of endangered species. In a 2023 position paper, the International Union for Conservation of Nature (IUCN) underscores the importance of zoos, aquariums, and botanical gardens in addressing worldwide biodiversity loss. However, a prerequisite for this role is that the reserve populations kept are stable, capable of reproduction, and viable in the long term. Lead author Prof. Marcus Clauss from the Faculty of Veterinary Medicine at the University of Zurich explains: “This trend must be halted and reversed. Zoos can only fulfill their conservation mandate if they maintain demographically stable and resilient reserve populations. That requires more young animals – and fewer old animals.”
Prof. Dierkes adds that the implications extend beyond conservation breeding: “Zoos also play a crucial role in education and research. They reach millions of visitors each year, raise awareness of biodiversity loss, the causes of species extinction, and the importance of nature conservation. Zoos are therefore important places of learning that strengthen understanding and support for species conservation in society. In addition, zoos enable important scientific studies on the behavior, reproduction, and health of endangered species. These findings help to improve husbandry in zoos and make conservation measures in the natural environment more effective. Declining animal numbers and aging populations would therefore not only significantly impair species conservation itself, but also the educational and research work of zoos. Consequently, population management in zoos should be more focused on demographic sustainability. Only if the current trend toward aging populations can be reversed will zoos be able to permanently fulfill their contribution to international species conservation.”
Journal
Proceedings of the National Academy of Sciences
Method of Research
Observational study
Subject of Research
Animals
Article Title
Aging populations threaten conservation goals of zoos
Article Publication Date
20-Jan-2026
Nash equilibria: The hidden math behind predator–prey behaviors
Using game theory, researchers show how attack and defense strategies emerge as stable behavioral dynamics
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Researchers used computational simulations to demonstrate how simple sensing and movement rules—such as detection of distance and speed changes—constrain predator–prey interactions.
In a simplified model, detection alone (without directional information) triggers movement responses, producing chasing, ambush, escape, or freezing behaviors. Varying sensory ranges and movement rules lead to predictable, stable attack and defense strategies consistent with Nash equilibrium, while also allowing flexible behavioral switching and sensory advantages to emerge naturally.
view moreCredit: Professor Hiroyuki Ichijo from the University of Toyama, Japan
Animal survival depends on effective attack and defense strategies, yet how these behaviors arise remains unclear. Addressing this question, a recent study shows that predator and prey behaviors emerge naturally as stable patterns shaped by simple sensory abilities and motor rules. These patterns correspond to Nash equilibria—states in which neither predator nor prey can improve its outcome by unilaterally changing behavior—providing a theoretical framework for understanding predator–prey interactions.
Nature is filled with remarkable diversity and complex interactions. However, its complexity is not random; it is shaped by systematic rules that determine how organisms behave. Attack and defense behaviors are among the most fundamental actions animals perform to survive. While predators use strategies such as chasing or ambushing to capture their prey, defense tactics, such as fleeing or freezing, are usually used by the prey to avoid being caught. Although these behaviors are widely observed in many species, an important question persists: On what basis do these behaviors arise, and why do they stay stable in different conditions?
Addressing this issue, a research team from the University of Toyama, led by Professor Hiroyuki Ichijo and Associate Professor Tomoya Nakamura from the Department of Anatomy, Faculty of Medicine, along with medical student Yuichiro Kawamura from the School of Medicine, used a computational approach to understand the strategic predator–prey behaviors. The researchers combined game theory with individual-based behavioral models and demonstrated that the seemingly complex attack and defense behaviors could be simply derived as Nash equilibrium strategies (a mathematically stable balance of behaviors). Their study was published in PLOS Computational Biology on November 21, 2025.
“Nash equilibria can explain stable predator–prey behaviors where neither predator nor prey benefits from changing its strategy unilaterally,” says Prof. Ichijo. “Remarkably, these stable behaviors arise from simple sensory and motor, without requiring complex assumptions.”
In the simulation model, the predator and prey “agents” were assigned only basic functions such as the ability to detect an opponent within a certain distance and the capacity to increase or decrease movement speed in response. When the researchers mathematically analyzed the predator–prey behavior using game theory, they found that specific combinations of detection ability and movement strategy consistently produced distinct and stable behavioral outcomes. Notably, even under these simplified conditions, the models reproduced well-known natural behaviors, such as chasing, ambushing, escaping, and freezing. For example, if a prey can detect predators from farther away, escaping becomes the best and most stable strategy, whereas certain sensing conditions for predators favored ambushing or chasing strategies.
“Interestingly, these behaviors emerged without assuming any complex cognitive processes or requiring fine-grained sensing abilities. Instead, they came simply from the basic rules of interaction, showing that complex behavior can grow out of simple mechanisms,” remarks Prof. Ichijo.
One key finding was that the predator–prey interactions were not always strictly competitive; in many simulated conditions, both predators and prey benefited simultaneously, challenging the traditional “winner-versus-loser” assumption. For instance, when predators could detect prey from farther away, they also competed more with each other, which in some situations helped prey populations survive better, even while predators were still successfully attacking.
This insight critically changes how scientists view predator-prey relationships. Instead of being a purely hostile battle, these interactions create situations where both sides independently benefit by engaging in the attack or defense behavior. Furthermore, the study also highlights the importance of sensory abilities for survival. Even subtle changes in the sensing or detection ability of an animal can completely alter its behavior, such as whether it chooses to run or freeze or decides to chase or wait in ambush. This effectively explains why sensory evolution is so strongly tied to behavioral adaptation in nature.
“Rather than focusing on the development of a specific technology, our research provides a general framework for understanding animal behavior in natural settings,” notes Prof. Ichijo. “This framework offers a theoretical basis for explaining why certain strategies emerge and remain stable in nature, and it may also inform future applications in robotics and AI.”
Overall, this study deepens our understanding of animal survival by showing that stable attack and defense strategies emerge naturally from behavioral patterns grounded in sensory capability and motor control. By mathematically identifying the Nash equilibria governing these interactions, the research bridges individual behavioral mechanisms with system-level stability, providing a robust theoretical model for understanding how survival is organized in nature.
About University of Toyama, Japan
University of Toyama is a leading national university located in Toyama Prefecture, Japan, with campuses in Toyama City and Takaoka City. Formed in 2005 through the integration of three former national institutions, the university brings together a broad spectrum of disciplines across its 9 undergraduate schools, 8 graduate schools, and a range of specialized institutes. With more than 9,000 students, including a growing international cohort, the university is dedicated to high-quality education, cutting-edge research, and meaningful social contribution. Guided by the mission to cultivate individuals with creativity, ethical awareness, and a strong sense of purpose, the University of Toyama fosters learning that integrates the humanities, social sciences, natural sciences, and life sciences. The university emphasizes a global standard of education while remaining deeply engaged with the local community.
Website: https://www.u-toyama.ac.jp/en/
About Professor Hiroyuki Ichijo from the University of Toyama, Japan
Hiroyuki Ichijo is a Professor in the Department of Anatomy at the University of Toyama in Japan. He earned his M.D. and Ph.D. from Kyoto Prefectural University of Medicine after graduating from Sapporo Medical University. He has held research and teaching positions at the Max Planck Institute for Developmental Biology and the University of Tsukuba. He pursues a wide range of interests and is known for challenging questions that are rarely addressed by others, with a focus on neuroscience and developmental neurobiology, particularly in the study of neural circuitry, axon guidance, and the relationships between brain structure and function.
Funding information
This study was supported by JSPS KAKENHI Grant-in-Aid for Scientific Research (C) (Hiroyuki Ichijo, JP21K06371; Tomoya Nakamura, JP22K07367).
Journal
PLOS Computational Biology
Method of Research
Computational simulation/modeling
Subject of Research
Animals
Article Title
Nash equilibrium of attack and defense behaviors between predators and prey
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