Urbanization linked to a 43 per cent drop in pollinating insects

University of Sheffield

Faceboo

XLinkedInWeChatBlueskyMessageWhatsApp
Email

 

image: 

Marmalade Hoverfly. Credit: Stuart Campbell

view more 

Credit: Stuart Campbell

*Images available*

• Urban landscapes support 43 per cent fewer pollinator species according to a new study from the University of Sheffield

• A research team conducted a comparative study at allotment sites in three major cities across England and found that those in more urbanised areas saw the highest decline in insect pollinator species

• The study found that relative to bees, nocturnal moths and hoverflies - which can be just as important for pollination - are particularly sensitive to the effects of urbanisation

• Researchers warn that more needs to be done to understand and conserve pollinating insects that are vulnerable to the effects of habitat loss through urbanisation

• Pollinating insects are vital for the reproduction of up to 90 per cent of wild flowering plant species and many crop species

Increasing urbanisation is linked to a decline in crucial pollinator populations, including nocturnal moths, hoverflies, and bees, according to a new study from the University of Sheffield.

The research, which paints a concerning picture for biodiversity, is published today (August 6, 2025) in the Royal Society's flagship biological research journal.

On allotment sites in Sheffield, Leeds and Leicester, a research team sampled pollinator species in a range of urban settings from city centres to more suburban areas. They found that there was a decline in species abundance and richness - up to 43 per cent - on allotments situated in more built-up areas.

The findings suggest that a wide range of pollinators are under threat in urban landscapes, and the researchers warn that more needs to be done to understand and conserve pollinating insects that are vulnerable to the effects of habitat loss through urbanisation.

Emilie Ellis, lead author of the study from the University of Sheffield’s School of Biosciences, said: “The scale of the threat to many pollinator species remains relatively unknown due to a global focus on bees. However moths and hoverflies are just as important for our ecosystems, and our results show they may be particularly vulnerable in urban habitats.

“Pollinating insects are vital for the reproduction of up to 90 per cent of wild flowering plant species and many crop species. As urbanisation causes more habitat loss, insect communities suffer and ecosystems become fragile. Our study identifies some of the features of urban greenspaces that are key to preserving and growing habitats for pollinators that are vulnerable to environmental change.”

The study shows that the cause of reduced pollinator diversity and abundance varies depending on the species, but is primarily driven through a reduction in the tree canopy and semi-natural habitat that form part of the green spaces found in our cities.

Jill Edmondson, senior author from the University of Sheffield’s School of Biosciences, said: “Allotments form greenspace oases in the urban landscape, with a rich mix of crops and flowers species to support pollinator communities, but, as the area of impervious surface (or the concrete, tarmac and buildings that often form the urban landscape we recognise) around allotments increased there was less habitat available for all pollinator groups. This may have consequences for crop pollination and ultimately yield in more urban allotments. 

“Our study demonstrates the importance of urban semi-natural spaces for insects, which we rely on, not just to make our gardens beautiful, but to support worldwide farming systems.”

Stuart Campbell, co-author from the University of Sheffield’s School of Biosciences, said: “All pollinating insects struggle to find suitable food and habitat in cities, but there haven’t been many studies directly comparing different groups. The greater sensitivity of hoverflies and moths to urbanisation might be due to their ecological requirements. 

“All of these species need flowers to feed on, but moths also require tree and shrub canopies, and food plants for their caterpillars, while many hoverflies require stagnant water to breed. These are all habitat characteristics that can be much harder to find in more heavily built up areas, and we will need to consider these features in order to conserve such a diverse group of insects for future generations.”

The team say the findings should underpin a more nuanced approach to pollinator conservation, and point out that more engagement with urban planners, stakeholders and policymakers is required to successfully protect the habitat features needed to support and sustain diverse pollinating insect communities in urban areas.

Emilie Ellis was funded by a PhD Scholarship from the Grantham Centre for Sustainable Futures with Jill Edmondson and Stuart Campbell as supervisors. Emilie is currently a postdoctoral associate with the Research Centre for Ecological Change at the University of Helsinki. 

The University of Sheffield’s School of Biosciences is working to solve some of the most pressing global challenges, from climate change and cancer, to sustainability and healthy ageing. Join us to study courses that cover the full breadth of biology, from molecular and cell biology, genetics, development, human physiology and pharmacology through to evolution, ecology, biodiversity conservation and sustainability.

ENDS

Poplar Hawkmoth. Credit: Emilie Ellis

Credit

Emilie Ellis

The University of Sheffield

The University of Sheffield is a leading Russell Group university, with a world-class reputation, ranked within the Top 100 universities in the world (QS World University Rankings 2026 and Times Higher Education World University Rankings 2025). Over 30,000 students from 150 countries study at Sheffield and in a truly global community, they learn alongside over 1,500 of the world’s leading academics.

Sheffield’s world-shaping research feeds into its excellent education. Students learn at the leading edge of discovery from researchers who are tackling today’s biggest global challenges. 

At its core, Sheffield is a place where independent thinkers can come together in pursuit of a shared ambition. To ask bold questions, push boundaries, and make a difference. This is what makes the University of Sheffield one of the best in the world.

From the first documented use of penicillin as a therapy in 1930, to building Europe’s largest research-led manufacturing cluster, Sheffield’s inventive spirit and top quality research environment sets it apart. 

Current research partners include Boeing, Rolls-Royce, Unilever, AstraZeneca, GlaxoSmithKline, Siemens and Airbus, as well as many government agencies and charitable foundations.

Sheffield was voted University of the Year in 2024 at the Whatuni Student Choice Awards - the largest annual university awards in the UK voted for exclusively by students. The award reflects a commitment to world-class education and an outstanding student experience. Its Students' Union, which is home to more than 350 societies and clubs, was also named Best Students’ Union in the UK for seven consecutive years between 2017-2024.

Over 300,000 Sheffield alumni from 205 different countries make a significant influence across the world, with six Nobel Prize winners included amongst former staff and students.

---

Journal

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2025.0102 

Article Publication Date

6-Aug-2025

Robot crab reveals how males compete in claw-waving contest

University of Exeter

FacebookXLinkedInWeChatBluesky

MessageWhatsAppEmail

 

image: 

Wavy Dave and a fiddler crab waving their claws. Credit Joe Wilde (1)

view more 

Credit: Joe Wilde

A robot crab has helped scientists understand how male fiddler crabs compete over females.

Male fiddler crabs have one oversized claw, and they attract females by standing outside their burrow and waving it.

In the new study, a robot crab – nicknamed Wavy Dave – waved its claw on a mudflat teeming with male fiddler crabs.

When the robot was waving, real males waved for longer in response, and they were less likely to retreat into their burrows – especially when the robot had a small claw.

The study – led by the Centre for Research in Animal Behaviour (CRAB) at the University of Exeter – suggests male crabs notice the behaviour of rivals and can adjust their behaviour in response.

“We know many animals adjust their sexual displays if rivals are nearby, but less is known about how they react to the actual displays themselves,” said Dr Joe Wilde, now at BioSS.

“If you own a shop and your rivals start selling things really cheaply, you might have to change how you run your business.

“The same might be true for males signalling to attract females – and our study suggests males do indeed respond to competition.

“Our findings reveal the subtle ways in which these crabs adjust their behaviour to compete in a dynamic environment, investing more in signalling when it is likely to be most profitable.”

Female fiddler crabs prefer males with a larger claw, and those that wave their claw quickly.

In the study – carried out in southern Portugal – males waved for longer when the robot was waving, but they did not wave faster.

Commenting on this, Dr Wilde said the crabs might interpret a waving rival as a signal that a female is around – but wait to see the female themselves before committing their full effort.

If a female enters a male’s burrow, the male fertilises her eggs. Once the eggs have hatched, the larvae float away to sea.

Males also retreat into their burrow at intervals for a variety of other possible reasons – including avoiding predators and fights with rivals, resting and wetting their gills.

‘Wavy Dave’ under attack

Thousands of crabs live on the mudflats where the study was conducted.

For each test, the robot crab was set up 30cm from a real male’s burrow, with two cameras recording.

The results show that males were less likely to compete when a rival had a larger claw, possibly because they expected to lose or were fearful of being attacked.

However, some crabs took issue with the robotic intruder.

“The females realised he was a bit odd, and some of the males tried to fight him,” said Dr Wilde.

“One male broke Wavy Dave by pulling off his claw. We had to abandon that trial and reboot the robot.”

Lockdown ‘pipedream’

Dr Wilde said Wavy Dave began as a “pipedream” during the Covid lockdown.

At the time, Dr Wilde was learning about 3D printing, and he happened to see that someone had created 3D scans of fiddler crabs and made them freely available.

He found a 3D printer to make a model, and taught himself enough robotics to make a crab that waved its claw. He then developed an app to control the crab via Bluetooth signals.

Dr Wilde’s work was funded by the Natural Environment Research Council GW4+ Doctoral Training Partnership.

The paper, published in the journal Proceedings of the Royal Society B, is entitled: “Biomimetic robots reveal flexible adjustment of sexual signalling in a wild invertebrate.”

Male fiddler crabs

Credit

Joe Wilde

Robot waving examples [VIDEO] | 

---

Journal

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2025.1570 

Article Title

Biomimetic robots reveal flexible adjustment of sexual signalling in a wild invertebrate

Article Publication Date

5-Aug-2025

 

Networks of long-distance female friends help gorillas move between groups

When moving to a new social group, female gorillas seek out groups containing females they have lived with in the past

Dian Fossey Gorilla Fund International

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

 

image: 

Networks of long-distance female friends help gorillas move between groups

A new study, published in Proceedings of the Royal Society B. Conducted by researchers from the University of Zurich and the Dian Fossey Gorilla Fund, funded by the Swiss National Science Foundation and Dian Fossey Gorilla Fund.

view more 

Credit: Dian Fossey Gorilla Fund

 

“I’m not going if I don't know anyone” -- sound all too familiar? Well it’s not just humans. Socialising in a new group can be tricky. We often rely on word of mouth and friends-of-friends connections. New research on gorillas suggests they may be using a similar strategy: when moving to a new social group, female gorillas seek out groups containing females they have lived with in the past. 

In many animal societies, individuals of one sex, or sometimes both, eventually leave their birth group to join another. In a smaller number of species, including humans and gorillas, individuals can change between groups multiple times. This process, known as dispersal, plays a key role in avoiding inbreeding, spreading gene diversity and shaping social relationships. But how do individuals choose where to go? 

A new study, published in Proceedings of the Royal Society B, cracks this mystery, thanks to more than 20 years of data on multiple groups of wild mountain gorillas, continuously monitored by the Dian Fossey Gorilla Fund in Rwanda. 

The study reveals that females do not disperse randomly. Broad group traits such as group size or sex ratio did not seem to matter, but past social experiences did, with females avoiding males they grew up with, and seeking out females they already knew. 

"Because female mountain gorillas do not know with certainty who their fathers are, they might rely on a simple rule like ‘avoid any group with males I grew up with’ as the likelihood of them being related will be higher than with males they did not grow up with,"said lead author Victoire Martignac, a Ph.D. student from the University of Zurich. 

And this rule is not just based on familiarity but also on its context. "Because females can disperse multiple times, they will become familiar with many males from different groups," explains Martignac, "yet, when choosing their next group, they only avoid males they grew up with. This really tells us that it’s not just who they know that matters but how they know them."

But what seemed to matter even more, was the presence of females they had lived with before, suggesting that these relationships matter even after years apart. 

"Going into a new group could feel pretty scary, with individuals usually entering at the bottom of the social hierarchy. A familiar female might help reduce this, providing a social ally," adds Dr. Robin Morrison, senior author on the study. "It could also act like a recommendation from a friend -- if a female they know has chosen to stay in this group it could indicate positive things about the group as a whole or the dominant male leading that group."

The study also found that it’s not just any familiar individuals, but females that had spent at least 5 years together and those that they had seen in the last two years which were the most influential.

The researchers argue that it is often wrongly assumed that individuals dispersing multiple times gain few benefits from being social as any member of the group might leave at any time.

But investing in these relationships clearly matters. Spatial separation can be ephemeral with individuals being reunited in the future, easing the difficult process of starting over in a new social group.

These findings highlight the deeply social nature of dispersal in gorillas, not only enabling the formation of new relationships, but also facilitating the maintenance of pre-existing ones. 

Crucially, these dispersal patterns, with individuals moving multiple times, combined with the fact that groups often interact and share overlapping ranges, all show that relationships can extend beyond group boundaries.

"This mirrors a key aspect of human societies: the existence of strong ties between different social groups," adds Martignac. "As humans, we’re constantly moving across jobs, cities and social groups. We do it so effortlessly that we forget how unusual this flexibility actually is within the animal kingdom."

"This is a reminder of the meaningfulness of social relationships kept across boundaries and how this extended network of relationships might have played a key role in the evolution of larger and more cooperative societies."

Finally, Dr. Tara Stoinski, president and CEO/chief scientific officer of the Dian Fossey Gorilla Fund and a co-author on the study emphasises that such discoveries are really only possible thanks to long-term data. "Being able to study dispersal, to track not only where individuals are from but also where they go, and to construct their whole social history in such detail, is only possible because of decades of data collection. With just a few years and a few groups, all of these inter-group ties and extended networks would be invisible to us. This really highlights the value of long-term observations on multiple groups in better understanding the evolution of sociality."

The research, conducted by researchers from the University of Zurich and the Dian Fossey Gorilla Fund, was funded by the Swiss National Science Foundation and Dian Fossey Gorilla Fund.

Group of mountain gorillas resting 



Three generations of mountain gorillas sitting together. Gutangara holding her infant daughter, next to her adult daughter Shishikara and grandson Kira

Two subadult female gorillas play together in Volcanoes National Park, Rwanda 



An encounter between two different mountain gorilla groups. These encounters represent an opportunity for females to learn about neighbouring groups and potentially disperse between them. 



Networks of long-distance female friends help gorillas move between groups

A new study, published in Proceedings of the Royal Society B. Conducted by researchers from the University of Zurich and the Dian Fossey Gorilla Fund, funded by the Swiss National Science Foundation and Dian Fossey Gorilla Fund.

Credit

Dian Fossey Gorilla Fund

---

Journal

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2025.0223 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Dispersed female networks: female gorillas’ inter-group relationships influence dispersal decisions

Article Publication Date

6-Aug-2025

WORD OF THE DAY

Why birds on the edge stay there: Study sheds light on murmuration mysteries

New research finds that sharp flock borders arise from simple rules of interaction—not from complex survival strategies

Rothamsted Research

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

They twist and turn across the sky in dense, whirling formations—murmurations of birds that seem to move as one, captivating watchers and puzzling scientists for decades. Now, a new analysis suggests that one of the most mysterious features of these aerial displays—the behaviour of birds at the edges—may stem from accident rather than intent.

A study examining the flocking patterns of jackdaws has found that the sharp borders of murmurations, and the way certain birds linger at the edges, can be explained by the mathematical rules that govern how individuals interact with their neighbours.

Scientists have long noted two peculiar features of flocking birds: those on the outer edges tend to remain there longer than expected, and the border of the flock appears remarkably well-defined, almost as if deliberately maintained. Previously, it was thought that these edge behaviours might have evolved as adaptive traits—perhaps allowing certain birds to spot predators more easily or respond faster to threats.

But according to the new study using stochastic (random) models of animal movement, these patterns emerge naturally when birds follow what are known as topological rules—coordinating their movement with a fixed number of nearby neighbours, regardless of the actual distance.

In contrast, the same striking edge behaviours did not emerge when birds interacted using metric rules, where coordination depends on who is physically closest. The findings were further supported by existing GPS tracking data from jackdaw flocks, which revealed patterns consistent with the topological model.

“What’s fascinating is that these highly structured, seemingly purposeful formations might actually be the result of very simple interaction rules,” said Rothamsted’s Andy Reynolds who conducted the analysis. “The sharpness of the border and the persistence of edge birds aren’t necessarily deliberate strategies. They’re just what happens when the system runs on topological interactions.”

The study adds to a growing body of evidence that complex group behaviours—from fish schools to insect swarms—can arise from surprisingly minimalist rules. It also raises questions about how much of animal group behaviour is shaped by evolution, and how much simply falls out of physics and geometry.

Murmurations, often seen in starlings but also performed by other species such as jackdaws, have long drawn both artistic and scientific fascination. While their precise function is still debated, they are believed to offer protection from predators and help in roosting.

This new research doesn’t rule out the idea that edge behaviours might be beneficial—but it suggests they may not have evolved for that purpose. Instead, they might be a fortunate accident of nature’s algorithm.

Rothasmted studies swarming behaviours in nature because they provide scientists with important information on how the various pest species that affect our crops might behave. By mathematically modelling what holds a swarm together, strategies can be developed that improve our ability to predict, monitor and control the movements of insect pests.

---

Journal

Journal of The Royal Society Interface

DOI

10.1098/rsif.2025.0020 

Method of Research

Computational simulation/modeling

Subject of Research

Animals

Article Title

Topological interactions account for border dynamics of murmurations and transit flocks

Article Publication Date

6-Aug-2025

On-board camera footage offers bird’s eye glimpse into seabird flights and feeding behaviour

Scientists have captured unique on-board footage of Indian Ocean seabirds speeding just above the waves to catch flying fish on the wing.

Lancaster University

LinkedIn
Message

 

image: 

Image of a red-footed boobie catching a flying fish on the wing. This is a still taken from video footage recorded by a camera mounted on a red-footed boobie in the Indian Ocean

view more 

Credit: Dr Ruth Dunn

Scientists have captured unique on-board footage of Indian Ocean seabirds speeding just above the waves to catch flying fish on the wing.

The footage, obtained by lightweight bird-borne cameras formed part of a study of the lives of seabirds in the waters around the remote archipelago they call home.

Two red-footed boobies - a tropical cousin of the more familiar gannet – were carefully fitted with the tiny cameras to record how they catch their favourite food; flying fish. Of 15 capture attempts, 14 were towards flying fish while in flight and one was an underwater dive.

This is the first such on-board footage revealing that flying fish are caught on the wing.

“The cameras recorded footage of the birds catching flying fish just above the surface of the water, while on the wing,” said Dr Ruth Dunn, a Visiting Researcher at Lancaster University and lead author of the study. “We suspected this happened, but this is the first time that we’ve had bird-borne footage like this showing them foraging and catching fish mid-air. It could suggest they are catching a significant portion of their diet in this way.”

In addition, the research team used small GPS and accelerator tracking devices on 18 more red-footed boobies in the remote Indian Ocean archipelago to show how they use the wind to travel hundreds of kilometres over the deep blue open ocean to hunt fish.

Red-footed boobies have long narrow wings relative to their bodies enabling them to glide quickly and efficiently in high crosswinds. The study showed they prefer tailwinds and crosswinds, especially on their outward journeys towards their feeding areas.

Red-footed boobies hunt in the open ocean and do not stick to specific feeding sites because their prey can be patchy and moves around. The researchers show the birds’ selection of favourable winds allows them to conserve energy while travelling and searching for food.

By selecting favourable winds, the birds reached higher speeds without needing to increase flapping. The researchers believe that the birds may have adapted this behaviour to the unpredictable, patchy food options available to them.

The trackers showed that the birds were more likely to continue to hunt in windier conditions and less likely to rest. This is possibly because when it is windier the flying fish stay in the air for longer which provides better opportunities for the birds to catch them.

“We found that the birds foraged in windy conditions and we think that this might be because flying fish are able to glide in the air for longer in these conditions, making them more accessible to the boobies,” said Dr Dunn.

Understanding how the behaviour of birds, and other flying species, are influenced by winds is of growing importance at a time when global airflow patterns and intensities are shifting due to climate change.

The red-footed booby findings contrast to those by other researchers studying some albatross species, which find it harder to catch prey in windier conditions.

The researchers believe their findings will help provide a clearer picture of how red-footed boobies will fare in a changing world.

“This is the first step in helping us to understand more about how wind influences the behaviour and distribution of tropical seabirds,” said co-author Professor Stephen Votier, from The Lyell Centre, Heriot-Watt University’s global institute for Earth and marine sciences. “By gaining a clearer understanding of such environmental effects will enable us to predict how they will cope in the future.”

The study, which was supported by the Bertarelli Foundation, involved researchers from Lancaster University, Heriot-Watt University, the University of Exeter, and ZSL.

Their findings are outlined in the paper ‘Commuting in crosswinds and foraging in fast winds: the foraging ecology of a flying fish specialist’ which is published in Proceedings of the Royal Society B.

---

Journal

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2025.0774 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Commuting in crosswinds and foraging in fast winds: the foraging ecology of a flying fish specialist

Article Publication Date

6-Aug-2025