New paper out in Current Biology

About ten years ago I was working in Cambridge as a research assistant with Dr Alex Thornton, studying a population of wild jackdaws. During the winter months we started observing the huge numbers of jackdaws roosting together, and got fascinated about the incredible timing of the birds all arriving and leaving the roosts at once. We started with some pilot studies of the roost at dawn and dusk, which showed the jackdaws were very vocal in the early morning and seemed to increasingly call more the closer to the moment they were to leave.

A mixed-corvid roost at dusk somewhere near Cambridge, UK. Photo copyright Jolle Jolles.

Many years later, Alex, who had now started a professorship at the University of Exeter, started looking at our questions again and decided to start a proper project to investigate the mechanisms underlying the massive departures of jackdaw roosts. Together with his master student Alex Dibnah, he was able to collect detailed observational data from a number of roosts across two winters. They also now ran a full-on playback experiment in the field to test our hypothesis that the jackdaws use vocalisations as a means to reach consensus decisions.

We observed the departures of roosts ranging from a couple hundred to a couple thousands of birds. While on some mornings jackdaws departed in a stream of small groups of individuals, on most mornings a majority or even the entire roost departed together and this happened almost at an instance, within a few seconds. By using audio recorders in the roost, we were able to record the calling of the birds and observed that the exact timing of departure of the roost was strongly linked to the calling of the jackdaws: the steeper the increase in calling intensity, the earlier the mass departure.

By a playback experiment in which we played calls of jackdaws in the roost, we were able to make the whole roost leave many minutes earlier than the predicted time of departure. Control playbacks of noise or wind did not induce any earlier departure. Hence, our playback experiments provides further evidence that it is the calling that mediates the timing of the jackdaws’ mass departures. Through their calls, jackdaws appear to effectively signal their willingness to leave, providing large groups with a means of achieving consensus to perform cohesive, collective departures from their roost.

Our study is published in Current Biology:
Dibnah, A. J., Herbert-read, J. E., Boogert, N. J., Mcivor, G. E., Jolles, J. W., & Thornton, A. (2022). Vocally mediated consensus decisions govern mass departures from jackdaw roosts. Current Biology, 32(10), R455–R456. https://doi.org/10.1016/j.cub.2022.04.032

New preprint out on predation risk in schooling prey

Predation is one of the main drivers of social grouping in animals. Hence, understanding when, where, and how predators attack animal groups, and the types of anti-predator benefits grouping animals may experience, has been of long-standing interest. Although it is well appreciated that there is differential predation risk within animal groups, our understanding has nonetheless remained largely focused on marginal predation and selfish herd effects.

In a new preprint (link) I just released with colleagues from the Max Planck Institute of Animal Behaviour and Princeton University, we try to overcome this gap. Specifically, we ran detailed experiments with live predators attacking live schools of prey to gain a detailed mechanistic understanding of when, where, and who predators attack in schooling prey.

By tracking the attacks in high spatial and temporal detail, we not only provide novel insights into predator decision-making, but show which key features related to both prey and predator predict individual’s risk to be targeted and survive attacks. Consideration of these multi-faceted factors underlying predation risk, in combination with predators’ attack strategy and decision-making, will have important consequences for understanding the costs and benefits of animal grouping and thereby the evolution of social and collective behaviour.

Reference
Jolles, J. W., Sosna, M. M. G., Mazué, G. P. F., Twomey, C. R., Rubenstein, D. I., and Couzin, I. D. (2021). Both Prey and Predator Features Determine Predation Risk and Survival of Schooling Prey. biorxiv, 1–20. doi:10.1101/2021.12.13.472101.

New paper out in Frontiers in Physiology

I am happy to say that an exciting paper that I worked on with Shaun Killen, Christos Ioannou, and others is now available online in Frontiers in Physiology. In the paper we line out physiological performance curves, the nonlinear changes in the physiological traits and performance of animals across environmental gradients, and discuss their potential to change social behaviour and group functioning, and the ecological consequences

Figure depicting how animals physiological performance may hypothetically change across different environmental variables (A) and the way in which individuals my differ from one another in their performance curves (B).

The paper leans heavily on my 2020 TREE paper with Shaun and Andrew King, but goes further by focusing on individual heterogeneity in variability between individuals. The work is mostly theoretical because there is still very little empirical work done, so looking forward to test some of the ideas myself with Shaun and colleagues next year in terms of how fish differ in how they respond to severe droughts. You can download the paper open access here!

Reference
Killen, S. S., Cortese, D., Cotgrove, L., Jolles, J. W., Munson, A., and Christos, C. (2021). The potential for physiological performance curves to shape environmental effects on social behaviour. Front. Physiol. 12, 754719. doi:10.32942/osf.io/bh968.

New paper out in Frontiers in Physics on variability in speed effects

I am excited to say that a new paper that I have been involved in came out today in Frontiers in Physics about the role of speed variability in collective animal behaviour.

A number of agent-based models have been developed to help understand how coordinated collective behaviour can emerge from simple interaction rules. Thereby, a common, simplifying assumption is that individual agents move with a constant speed. In this paper together with the team of Pawel Romenczuk and colleagues in Berlin, we critically re-asses this assumption and provide new theoretical evidence that shows variability in the speed of individuals can have profound effects on the emergent collective patterns.

A quick visualisation of some differently simulated groups differing in size and speed variability

I have long been working on the role of individual heterogeneity in collective behaviour and was therefore excited to collaborate with Pawel and his team to run in-depth computer simulations to start better consider behavioural variability as a source of heterogeneity in animal groups. You can find the paper (open access) here.

Reference:
Klamser, P. P., Gómez-Nava, L., Landgraf, T., Jolles, J. W., Bierbach, D., and Romanczuk, P. (2021). Impact of Variable Speed on Collective Movement of Animal Groups. Front. Phys. 9, 1–11. doi:10.3389/fphy.2021.715996.

New opinion paper out in TREE on fisheries effects on shoaling

Today my latest paper came out in Trends in Ecology and Evolution. Co-led by Valerio Sbragaglia at ICM in Barcelona (joint first-authorship) and with Marta Coll and Robert Arlinghaus, we provide a new perspective about the role that fisheries may have on the shoaling tendency and collective behaviour of exploited fish species. Besides discussing the different potential mechanisms (see also figure below), we highlight potential consequences for fish populations and food webs, and discuss possible repercussions for fisheries and conservation strategies.

It has been nice to work on the ideas of this paper and focusing a bit more on the important practical implications of my main research topic of individual heterogeneity and collective animal behaviour. I am looking forward to further work I will be doing with Valerio and our colleagues to start test some of the ideas we put forward in our paper and co-supervise students on the topic.

You can find the paper online here as well as a press release regarding our article. If you cannot access the paper, please send me an email!

Reference
Sbragaglia, V., Jolles, J. W., Coll, M., and Arlinghaus, R. (2021). Fisheries-induced changes of shoaling behaviour: mechanisms and potential consequences. Trends Ecol. Evol. 36, 885–888. doi:10.1016/j.tree.2021.06.015.

New paper out in MEE on potential of Raspberry Pi’s in biology

Single-board computers like the Raspberry Pi have taken the world by storm and are being used in almost any situation imaginable. In a new open-access paper I published in the journal Methods in Ecology and Evolution, I now show these low-cost open-source computers are also increasingly being used in science and highlight how the Raspberry Pi can play a fundamental role to further revolutionise biological research.

By reviewing the biological literature, I found over a hundred empirical studies across the biological domain that implemented the Raspberry Pi in some way, both in the lab, the field, and in the classroom. The list of applications is almost endless, and ranges from weather stations, and automated bird feeders, to closed-loop learning devices, deep-sea recording systems, environmental monitoring tools, and wild-life camera traps.

The broad capabilities of the Raspberry Pi, combined with its low cost, ease of use and large user community make it a great research tool for almost any project. But despite its increasing uptake by the scientific community, the Raspberry Pi is not the common research tool that it actually could be.

To stimulate its uptake and help researchers integrate the Raspberry Pi in their work, I provide detailed recommendations, guidelines, and considerations, and developed a dedicated website (raspberrypi-guide.github.io) with over 30 easy-to-use tutorials.

I believe low-cost micro-computers like the Raspberry Pi are a powerful tool that can help transform and democratize scientific research, and will ultimately help push the boundaries of science. I therefore hope my paper will help generate more awareness about the Raspberry Pi among scientists and help advance our understanding of biology, from the micro- to the macro-scale.

Source
Jolles, J. W. (2021). Broad‐scale applications of the Raspberry Pi: A review and guide for biologists. Methods Ecol. Evol. 12, 1562–1579. doi:10.1111/2041-210X.13652

Update: My paper has been picked up by the Raspberry Pi Blog (link), scidev.net (link), and Niche magazine of the British Ecological Society (link, p12), among others!

New paper and software package: pirecorder!

Paper screenshot

My latest paper has just been published in the Journal of Open Source Software! It is the paper that accompanies my Python package pirecorder, which facilitates controlled and automated image and video recordings with optimal settings for the raspberry pi, specifically developed for biological research.

So far, researchers have often relied on writing their own recordings scripts to take still photographs and videos from the command line.

Although some specific software solutions exist, what was missing is a complete solution that helps researchers, especially those with limited coding skills, to easily set up and configure their raspberry pi to run large numbers of controlled and automated image and video recordings.

pirecorder was developed to overcome this need. You can get a quick overview of the package and what it is capable of in the video below:


Pirecorder is open source via GitHub, https://github.com/JolleJolles/pirecorder, easy to install using pip (pip install pirecorder), and comes with its own dedicated documentation website: https://jollejolles.github.io/pirecorder/.

The accompanying paper is published in the Journal of Open Source Software:

Jolles, J.W. (2020). pirecorder: controlled and automated image and video recording with the raspberry pi. Journal of Open Source Software 5(54), 2584. doi: 10.21105/joss.02584.

New paper out in Biology Letters

Today my latest paper came out in Biology Letters! You can find it here.

The spectacular and complex visual patterns created by animal groups moving together have fascinated humans since the beginning of time. Think of the highly synchronized movements of a flock of starlings, or the circular motion of a school of barracudas. Using state-of-the-art robotics, a research team from the University of Konstanz, Science of Intelligence, and the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) shows that animals’ speed is fundamental for collective behavioral patterns, and that ultimately it is the faster individuals that have the strongest influence on group-level behavior. The study, published in Biology Letters of the Royal Society, gives new insights on complex collective behavioral patterns in nature, and provides knowledge that could help develop robotic systems that move collectively, such as robot swarms, driverless cars, and drones.

Researchers have long focused on identifying the emergence of collective patterns. Thanks to a combination of behavioral experiments, computer simulations, and field observations, it is clear that many seemingly complex patterns can actually be explained by relatively simple rules: move away from others if they get too near, speed up towards others if they get too far away, and otherwise move at the same speed and align with your group mates.

Besides understanding the rules that individuals follow when interacting with others, we need to consider the behaviors and characteristics of those individuals that make up the group and determine their influence for collective outcomes” says Dr. Jolle Jolles, a scientist at the Zukunftskolleg, University of Konstanz, and lead author of the study. “Across the animal kingdom, it has been found again and again that animals tend to differ considerably from one another in their behavior such as in terms of their activity, risk-taking, and social behavior“. What are the consequences of this behavioral heterogeneity when it comes to collective behavior? And how can one test for its social consequences?

To disentangle the role of individual differences in collective behavior and the mechanisms underlying this type of behavior, the research team built “Robofish”, a robotic fish that not only realistically looks and behaves like a guppy – a small tropical freshwater fish – , but also interacts with the live fish in a natural way. The experimenters paired the robotic fish with a guppy and programmed it to always follow its partner and copy its movements, lacking however any movement preferences of its own. The team then used high-definition video tracking and a closed-loop feedback system to let the robotic fish respond to the live fish’s actions in real-time.

One of Robofish’s simple interaction rules was to keep a constant distance to its shoal mate” explains Dr. David Bierbach, who works within the Berlin-based Excellence Cluster ‘Science of Intelligence’ at the HU Berlin and the IGB, and is senior author on the paper. “Using this rule, our Robofish tried to keep the same distance to the live fish by accelerating and decelerating whenever the live fish did. Also, programming the robotic fish without any own movement preferences gave us the unique opportunity to investigate how individual differences in the behavior of the live fish led to group-level differences. In short, with our unique approach, we could isolate the effect of the fish’s movement speed on the pair’s collective behavior“.

The researchers first quantified the guppies’ natural movement speed by observing their movements when alone in an open environment, and found that there were large individual differences in how fast guppies tended to move. When the fish were subsequently tested with Robofish, the fish and Robofish tended to swim naturally together as a pair. However, the researchers observed that there were large differences in the social behaviors between the pairs: pairs in which the guppy had a faster movement speed tended to be much more aligned, more coordinated, and less cohesive, and the guppy emerged as a clearer leader. As Robofish behaved according to the same identical rules with each and every guppy, it is the individual speed of the guppies that must have led to these differences in group-level properties.

By involving state-of-the-art robotics, this research shows that individual speed is a fundamental factor in the emergence of collective behavioral patterns. As individual differences in speed are associated with a broad range of phenotypic traits among grouping animals, such as their size, age, and hunger level, the results of this study may help understand the role of such heterogeneity in animal groups.

Future studies using the interactive Robofish will focus on other aspects of collective behavior: For example, how can animals act in synchrony if they just respond to the actions of their neighbors? “We want to improve Robofish’s software so that it can predict and anticipate the live fish’s next steps, which is assumed to be how animals do it.” says David Bierbach.

Understanding these mechanisms is not only fundamentally important as it reveals information about the mechanisms that underlie collective behavior and decisions, but also because this knowledge can be applied to artificial systems and used to develop machines that move collectively, such as robot swarms, driverless cars, and drones.

New paper in Scientific Reports

Today my latest paper Schistocephalus parasite infection alters sticklebacks’ movement ability and thereby shapes social interactionshas been published in Scientific Reports! Although many fundamental aspects of host-parasite relationships have been unravelled, few studies have systematically investigated how parasites affect organismal movement. In this study we combine behavioural experiments of Schistocephalus solidus infected sticklebacks with individual-based simulations to understand how parasitism affects individual movement ability and how this in turn influences social interaction patterns.

By detailed tracking of the movements of the fish, we found that infected fish swam slower, accelerated slower, turned more slowly, and tended to be more predictable in their movements than did non-infected fish. Importantly, the strength of these effects increased with increasing parasite load (% of body weight), with the behaviour of more heavily infected fish being more impaired.

When grouped, pairs of infected fish moved more slowly, were less cohesive, less aligned, and less coordinated than healthy pairs. Mixed pairs exhibited intermediate behaviours and were primarily led by the non-infected fish. These social patterns emerged naturally in model simulations of self-organised groups composed of individuals with different speeds and turning tendency, consistent with changes in mobility and manoeuvrability due to infection.

Together, our results demonstrate how infection with a complex life cycle parasite affects the movement ability of individuals and how this in turn shapes social interactions, providing important mechanistic insights into the effects of parasites on host movement dynamics. Download our open access paper here!

New preprint about robofish and group-behaviour

Today I released a new preprint on bioRxiv, Group-level patterns emerge from individual speed as revealed by an extremely social robotic fish, which is the result of a great collaboration with David Bierbach and colleagues at the Humboldt Universität zu Berlin.

In this paper we present results of an experiment to investigate how the speed of individual group members leads to group-level patterns. We paired guppies with a biomimetic robot that was programmed to always follow and lack any individual preferences of its own. We used a state-of-the art closed-loop tracking and feedback system to be able to properly control for the influence of individual heterogeneity of the individual’s group members.

We show that individual differences in guppies’ movement speed were highly repeatable and shaped key collective patterns: higher individual speeds resulted in stronger leadership, lower cohesion, higher alignment, and better temporal coordination in the pairs. By combining the strengths of individual-based models and observational work with state-of-the-art robotics, we provide novel evidence that individual speed is a key, fundamental process in the emergence of collective behaviour.

New paper out in TREE and on the front cover!

I am excited to say that our review in Trends in Ecology and Evolution, after already being available online, is out now in print and is shining on the front cover! I took this photo of this stunning stickleback school while snorkelling in the Bodensee to study their collective behaviour. Read our open access paper here.

New paper out on personality, plasticity, and predictability

Today my latest paper came out in Animal Behaviour, one of my favourite journals. It is titled “Personality, plasticity and predictability in sticklebacks: bold fish are less plastic and more predictable than shy fish“. In this paper, which is a result of a collaboration with Neeltje Boogert and Yimen Araj-Ayoy and a MSc project of Helen Briggs, we present an extensive experimental study focused on better understanding the sources of behavioural variation among individual animals.

In short, we tested 80 three-spined sticklebacks repeatedly on their boldness across a 10-week testing period and automatically tracked their movements. We then employed advanced statistical model techniques (GLMMs and DHGLMs) to use this large behavioural dataset to investigate the potential links between the personality (consistent differences in average behaviour), the plasticity (how individuals change their behaviour over time/contexts), and predictability (the remaining intra-individual variation after accounting for personality and plasticity differences) in behaviour.

Besides detecting large consistent individual differences in boldness and the extent to which fish changed this behaviour over time (temporal plasticity), we found that boldness personality and plasticity were negatively linked, with bold fish changing little in their behaviour over time. Interestingly, there were still large individual differences in the remaining behavioural variation, with bold fish showing much less behavioural variation and thus behaving more predictable than shy fish. Importantly, these results suggest that boldness, plasticity and predictability may be fundamentally linked and form part of the same behavioural syndrome.

Jolles, J. W., Briggs, H. D., Araya-Ajoy, Y. G., & Boogert, N. J. (2019). Personality, plasticity and predictability in sticklebacks: bold fish are less plastic and more predictable than shy fish. Animal Behaviour, 154, 193–202.

The paper, which was one of the Editor’s Choice papers for August 2019, can be found here.

New paper out in ProcB on group repeatability

From swarm to school, stickleback groups differ repeatedly in their collective performance  

 among schooling fish, groups can have different collective personalities, with some shoals sticking closer together, being better coordinated, and showing clearer leadership than others.

For centuries, scientists and non-scientists alike have been fascinated by the beautiful and often complex collective behaviour of animal groups, such as the highly synchronised movements of flocks of birds and schools of fish. Often, those spectacular collective patterns emerge from individual group members using simple rules in their interactions, without requiring global knowledge of their group.

In recent years it has also become apparent that, across the animal kingdom, individual animals often differ considerably and consistently in their behaviour, with some individuals being bolder, more active, or more social than others.

New research conducted at the University of Cambridge’s Department of Zoology suggests that observations of different groups of schooling fish could provide important insights into how the make-up of groups can drive collective behaviour and performance.

In the study, published today in the journal Proceedings of the Royal Society B, the researchers created random groups of wild-caught stickleback fish and subjected them repeatedly to a range of environments that included open spaces, plant cover, and patches of food.

Read further…

New paper out in Current Biology!

My latest paper on the collective behaviour of stickleback shoals is out today in the journal Current Biology!

Jolles, JW, Boogert, NJ, Sridhar, VH, Couzin, ID, Manica, A. (2017) Consistent individual differences drive collective behaviour and group functioning of schooling fish. Current Biology 27: 1-7. doi: 10.1016/j.cub.2017.08.004 (link).

Highly coordinated school of three-spined sticklebacks swimming in the blue waters of the Bodensee near Konstanz, Southern Germany. Photo: Jolle W. Jolles

Highly coordinated school of three-spined sticklebacks swimming in the blue waters of the Bodensee near Konstanz, Southern Germany. Photo: Jolle W. Jolles

New research sheds light on how “animal personalities” – inter-individual differences in animal behaviour – can drive the collective behaviour and functioning of animal groups such as schools of fish, including their cohesion, leadership, movement dynamics, and group performance. These research findings from the University of Konstanz, the Max Planck Institute of Ornithology and the University of Cambridge provide important new insights that could help explain and predict the emergence of complex collective behavioural patterns across social and ecological scales, with implications for conservation and fisheries and potentially creating bio-inspired robot swarms. It may even help us understand human society and team performance. The study is published in the 7 September 2017 issue of Current Biology.

Read further…

New paper on boldness, sociability and leadership in Animal Behaviour

Recent research of colleagues and I at the University of Cambridge has revealed that sticklebacks with bolder personalities are not only better leaders but also less sociable than more timid fish. The behaviour of these bolder fish shapes the dynamics of the group.

See a 4min video about our research here http://youtu.be/5TSim9TkXiwSee a 4min video about the paper here: http://youtu.be/5TSim9TkXiw

Throughout the animal kingdom, individuals often live and move together in groups, from swarms of insects to troops of primates. Individual animals may benefit from being part of groups, which provide protection from predators and help in finding food. To ensure that individuals reap the benefits of togetherness, group members coordinate their behaviour. As a result, leaders and followers emerge.

Within groups, animals differ from each other in how they cope with their environment and often exhibit distinctive traits, such as boldness or sociability. Even three-spined sticklebacks, the ‘tiddlers’ collected from streams and ponds by generations of schoolchildren, can be described in terms of their personalities: some are bolder and take more risks, while others are more timid and spend more of their time hiding in the weeds.

Research carried out in the Zoology Department at the University of Cambridge suggests that observations of these tiny fish, and how they interact with one another, could provide important insights into the dynamics of social groups, including humans.

Jolle Jolles, lead author of the study, said: “Although we now know that the spectacular collective behaviours we find throughout the animal kingdom can often be explained by individuals following simple rules, little is known about how this may be affected by the personality types that exist within the group.

Experimental design. Fish were tested twice for one hour in the risk-taking task during two subsequent sessions. During the pairing session fish could see and interact with one another through a transparent partition.

Experimental design. Fish were tested twice for one hour in the risk-taking task during two subsequent sessions. During the pairing session fish could see and interact with one another through a transparent partition.

“Our research shows that personality plays an important role in collective behaviour and that boldness and sociability may have significant, and complementary, effects on the functioning of the group.”

In the study, the researchers studied the behaviours of sticklebacks in tanks containing gravel and weed to imitate patches of a riverbed. The tanks were divided into two lanes by transparent partitions and randomly-selected pairs of fish were placed one in each lane. Separated by the see-through division, the fish were able to see and interact with one another.

stickleback-tracking-perosnality

The positions and movements of the individual sticklebacks were recorded using sophisticated tracking technology, enabling accurate comparisons to be made of each fish’s role in the collective movement of the pair.

“We found that individuals differed considerably and consistently in their tendency to approach their partner,” said Jolles. The study showed that more sociable individuals tended to be coordinated in their behaviour while less sociable individuals were more inclined to lead.

Dr Andrea Manica, reader at the Department of Zoology and co-author of the paper, added: “Our research revealed that the tendency of fish to approach their partner was strongly linked to their boldness: bolder fish were less sociable than their more timid group mates.”

Jolles explains that sociability may form part of a broader behavioural syndrome. “Our results suggest that bolder, less sociable individuals may often lead simply because they are less reluctant to move away from their partners, whereas shyer, more sociable, individuals become followers because they prioritise staying close to others,” he said.

fig1

“Differences in boldness and sociability may be expressions of underlying risk-prone or risk-averse behavioural types, as risk-averse individuals may be more motivated to group together and to respond to other individuals in order to avoid predation.”

The findings of this study suggest that leadership and group coordination can be strongly affected by personality differences in the group and that boldness and sociability may play important but complementary roles in collective behaviour.

Jolles added: “Now we know these personality traits affect the collective movements of pairs of fish, the next step is to understand their role in the functioning and success of larger, more dynamic groups.”

See a 4min video in which we explain our paper in more detail below:

jolles-animal-behaviour-stickleback-leadershipClick here to download the paper.

Jolles JW, et al. (2015) The role of social attraction and its link with boldness in the collective movements of three-spined sticklebacks. Animal Behaviour, published online 2 Dec. Doi: 10.1016/j.anbehav.2014.11.004

Leadership in fish affected by previous experiences and linked to personality

Leadership behaviour is affected by social experiences from previous partners and depends on an individual’s personality, as shown by our latest study with three-spined stickleback fish, now published in Behavioral Ecology.

sticklebacks

From the political affairs we see on the news, to making decisions with your friends, leadership is all around us. But next to humans, leaders and followers can also be found in many group-living animals, such as fish, birds, and primates.

Social animals may receive benefits from grouping such as protection from predators and help in finding food. But to ensure individuals reap the benefits of grouping, they must time and coordinate their behaviour with the emergence of potential leaders and followers as a result.
Read further…