Charlotte K Hemelrijk

Charlotte K Hemelrijk
University of Groningen | RUG · Faculty of Mathematics and Natural Sciences

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182
Publications
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Publications

Publications (182)
Article
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The causes and consequences of being in a particular dominance position have been illuminated in various animal species, and new methods to assess dominance relationships and to describe the structure of dominance hierarchies have been developed in recent years. Most research has focused on same-sex relationships, however, so that intersexual domin...
Article
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The coordinated motion of large flocks of starlings is fascinating for both laymen and scientists. During their aerial displays, the darkness of flocks often changes, for instance dark bands propagate through the flock (so-called agitation waves) and small or large parts of the flock darken. The causes of dark bands in agitation waves have recently...
Preprint
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Collisions between birds and airplanes, bird strikes, can damage aircrafts, resulting in delays and cancellation of flights, costing the international civil aviation industry more than 1.4 billion U.S. dollars annually. Bird deterrence is therefore crucial, but the effectiveness of all available deterrence methods is limited. For example, live avia...
Article
Full-text available
Complex patterns of collective behaviour may emerge through self-organization, from local interactions among individuals in a group. To understand what behavioural rules underlie these patterns, computational models are often necessary. These rules have not yet been systematically studied for bird flocks under predation. Here, we study airborne flo...
Article
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Bird flocks under predation demonstrate complex patterns of collective escape. These patterns may emerge by self-organization from local interactions among group-members. Computational models have been shown to be valuable for identifying what behavioral rules may govern such interactions among individuals during collective motion. However, our kno...
Preprint
Full-text available
Bird flocks under predation demonstrate complex patterns of collective escape. These patterns may emerge by self-organization from simple interactions among group-members. Computational models have been shown to be valuable for identifying the behavioral rules that may govern these interactions among individuals during collective motion. However, o...
Article
The “selfish herd” hypothesis¹ provides a potential mechanism to explain a ubiquitous phenomenon in nature: that of non-kin aggregations. Individuals in selfish herds are thought to benefit by reducing their own risk at the expense of conspecifics by attracting toward their neighbors’ positions¹,² or central locations in the aggregation.3, 4, 5 Alt...
Article
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Activity and autonomous motion are fundamental in living and engineering systems. This has stimulated the new field of ‘active matter’ in recent years, which focuses on the physical aspects of propulsion mechanisms, and on motility-induced emergent collective behavior of a larger number of identical agents. The scale of agents ranges from nanomotor...
Preprint
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We develop an experimental method to induce controlled and local perturbations in a group of fish. Using the paradigm of the shuttle box we condition aversive escape reactions in groups of rummy-nose tetra ( Hemigrammus rhodostomus ) in response to a green light. Our experiments suggest that aversive conditioning can (i) be used successfully in thi...
Article
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When a predator attacks a flock of starlings (Sturnus vulgaris), involving thousands of individuals, a typical collective escape response is the so-called agitation wave, consisting of one or more dark bands (pulses) propagating through the flock and moving away from the predator (usually a Peregrine falcon, Falco peregrinus). The mechanism underly...
Article
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In common with many other raptors, female Peregrine Falcons Falco peregrinus are about 50% heavier than males. Their sexual dimorphism is thought to allow breeding pairs to exploit a wider range of prey through a division of labor: the male being able to catch more maneuverable prey species; the female capable of carrying larger ones. Given the dif...
Article
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Collective behaviour of animals has been a main focus of recent research, yet few empirical studies deal with this issue in the context of predation, a major driver of social complexity in many animal species. When starling (Sturnus vulgaris) flocks are under attack by a raptor, such as a peregrine falcon (Falco peregrinus), they show a great diver...
Article
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Examining how animals direct social learning during skill acquisition under natural conditions, generates data for examining hypotheses regarding how transmission biases influence cultural change in animal populations. We studied a population of macaques on Koram Island, Thailand, and examined model-based biases during interactions by unskilled ind...
Article
Moving animal groups such as schools of fishes or flocks of birds often undergo sudden collective changes of their travelling direction as a consequence of stochastic fluctuations in heading of the individuals. However, the mechanisms by which these behavioural fluctuations arise at the individual level and propagate within a group are still unclea...
Article
Full-text available
The peregrine falcon Falco peregrinus is renowned for attacking its prey from high altitude in a fast controlled dive called a stoop. Many other raptors employ a similar mode of attack, but the functional benefits of stooping remain obscure. Here we investigate whether, when, and why stooping promotes catch success, using a three-dimensional, agent...
Data
Alternative delay implementation. In our model, a parameter τ affects both the differencing time of the line-of-sight, as well as the sample rate from vision to guidance. Here, we show that our results are not implementation specific. When we implement a continuous delay function with analytic differentiation, the same qualitative patterns are foun...
Data
Change in bank angle over time for different step sizes. It portrays the bank angle change over time of a falcon stooping at 100ms−1, and exerting a roll acceleration of 5000 rad s−2 using Bang-Bang control to turn π rad. (EPS)
Data
Video of simulated attacks by peregrine falcons in level flight on starlings in smooth maneuvering flight. The camera is set up to follow the falcon from below at a fixed position, mimicking how a human observer would view the spectacle. The falcon misses the starling three times and catches it once. A catch is defined as occurring when the model-f...
Data
Video of simulated attacks by peregrine falcons in level flight on starlings in smooth maneuvering flight. The falcon misses in the first two attacks and catches the starling in the third. A catch is defined as occurring when the model-falcon comes within 0.2m of the model-starling. A near-miss occurs (“MISS!” appears on the screen in the video) wh...
Data
Video of simulated attacks by peregrine falcons in stooping flight on starlings in non-smooth maneuvering flight. The falcon catches the starling three times and misses it once. A catch is defined as occurring when the model-falcon comes within 0.2m of the model-starling. A near-miss occurs (“MISS!” appears on the screen in the video) when the mode...
Data
Example of a trajectory using a time step size 10−4s or 10−5s. The differences of the trajectories of the prey and predator between step sizes is marginal (i.e. the trajectories converge), and we thus use the larger step size such that run-time of the simulations is minimized. (EPS)
Data
Video of simulated attacks by peregrine falcons in level flight on starlings in straight flight. The starling is caught by the falcon in the two attacks of the video, where a catch occurs when the falcon comes within 20cm of the starling. Colored ribbons behind the birds show their recent trajectories, and follow the motion of the wings; the white...
Data
Video of simulated attacks by peregrine falcons in level flight on starlings in non-smooth maneuvering flight. The falcon misses the starling three times and catches it once. A catch is defined as occurring when the model-falcon comes within 0.2m of the model-starling. A near-miss occurs (“MISS!” appears on the screen in the video) when the model-f...
Data
Prey accelerations. The figure portrays the distribution of prey accelerations along the x, y and z axes of the inertial axis system, for smooth and non-smooth maneuvering prey. (EPS)
Data
Flight trajectories. Examples of flight trajectories of the falcon when hunting non-smooth maneuvering prey, and when the navigation constant N of the falcon is low (N < 2). In some curved flight paths, the peregrine falcon drops below the prey; a phenomenon also observed in nature. (EPS)
Preprint
Full-text available
Moving animal groups such as schools of fish or flocks of birds often undergo sudden collective changes of their travelling direction as a consequence of stochastic fluctuations in heading of the individuals. However, the mechanisms by which these behavioural fluctuations arise at the individual level and propagate within a group are still unclear....
Article
This review demonstrates that many patterns of complex social behavior in group-living animals, in particular primates, may emerge by self-organization from cognitively “simple” competitive and affiliative interactions among group members. We focus on the lessons learnt from the different versions of model DomWorld. In these computational models, v...
Article
Full-text available
The confusion effect describes the phenomenon of decreasing predator attack success with increasing prey group size. However, there is a paucity of research into the influence of this effect in coherent groups, such as flocks of European starlings (Sturnus vulgaris). Here, for the first time, we use a computer game style experiment to investigate t...
Article
Compared to men, women less often attain high-level positions and generally have lower status in society. In smaller groups, the relative influence of men and women depends on gender composition, but research is inconclusive regarding the relation between gender composition and female influence. Studies of nonhuman primates show that when females a...
Article
Compared to men, women less often attain high level positions and generally have lower status in society. In smaller groups the relative influence of men and women depends on gender composition, but research is inconclusive regarding the relation between gender composition and female influence. Studies of non-human primates show that when females a...
Article
Full-text available
The long-term effects of early adverse experiences on later psychosocial functioning are well described in humans, but sparsely documented for chimpanzees. In our earlier studies, we investigated the effects of maternal and social deprivation on three groups of ex-laboratory chimpanzees who experienced either an early or later onset of long-term de...
Article
GrooFiWorld is an individual-based, computational model of social interactions that can be used to examine factors underlying reciprocation and interchange of social behavior in primate societies. Individuals within GrooFiWorld are programed to maintain spatial proximity and thereby form a group. When an individual encounters another individual in...
Chapter
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In primates, cooperative acts have been observed such as communal rearing of offspring, cooperative mobbing of predators, supporting others in fights, and grooming others. Grooming builds up a social bond between the partners, helps in repairing relationships, and produces all kinds of benefits for the groomee, such as the reduction of parasites an...
Article
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One hypothesis about the origins and evolution of coordinated animal movements is that they may serve as a defensive mechanism against predation. Earlier studies of the possible evolution of coordinated movement in prey concentrated on predators with simple attack tactics. Numerous studies, however, suggest that to overcome the apparent defensive m...
Article
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In a computational model of hydrodynamics based on the Multiple Collision Dynamics modelling technique, we investigate hydrodynamic advantages of fish swimming in an infinite school. We show that the average Froude efficiency of individuals swimming in a school is higher than of individuals swimming solitarily for each of four spatial configuration...
Article
Full-text available
Moving in a group while avoiding collisions with group members causes internal dynamics in the group. Although these dynamics have recently been measured quantitatively in starling flocks (Sturnus vulgaris), it is unknown what causes them. Computational models have shown that collective motion in groups is likely due to attraction, avoidance and, p...
Article
Full-text available
Fast transfer of information in groups can have survival value. An example is the so-called wave of agitation observed in groups of animals of several taxa under attack. It has been shown to reduce predator success. It usually involves the repetition of a manoeuvre throughout the group, transmitting the information of the attack quickly, faster tha...
Article
Full-text available
Different forms of sociality have evolved via unique evolutionary trajectories. However, it remains unknown to what extent trajectories of social evolution depend on the specific char-acteristics of different species. Our approach to studying such trajectories is to use evolu-tionary case-studies, so that we can investigate how grouping co-evolves...
Article
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Reciprocation and interchange of grooming and support may emerge as a consequence of the socio-spatial structure of the group through which individuals interact with certain partners more frequently than with others. This is shown in a computational model of grouping, fighting, and grooming, called Groofiworld. In this case, no specific mechanism o...
Article
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Coordination of birds in large flocks is amazing, especially, since individual birds only interact with a few neighbors (the so-called ‘influential neighbours’). Yet, empirical data show that fluctuations of velocity and speed of different birds are correlated beyond the influential neighbours and are correlated over a larger distance in a larger f...
Article
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Post-conflict affiliation between former opponents and bystanders occurs in several species of non-human primates. It is classified in four categories of which affiliation received by the former victim, 'consolation', has received most attention. The hypotheses of cognitive constraint and social constraint are inadequate to explain its occurrence....
Article
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Whether any non-human animal can attribute mental states to others remains the subject of extensive debate. This despite the fact that several species have behaved as if they have a ‘theory of mind’ in various behavioral tasks. In this paper, we review the reasons of skeptics for their doubts: That existing experimental setups cannot distinguish be...
Article
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Herds of ungulates, flocks of birds, swarms of insects and schools of fish move in coordinated groups. Computer models show that only one or very few animals are needed to initiate and direct movement. To investigate initiation mechanisms further, we studied two ways in which movement can be initiated in feral horses: herding, and departure from th...