Collective Animal Behaviour

CUDA simulation movie

Research in the Collective Animal Behaviour Laboratory involves the study of adaptive collective phenomena in animal groups such as bird flocks, fish schools and insect swarms using a combined experimental and theoretical approach. Animal groups frequently exhibit complex and coordinated collective behaviours that result from social interactions among individuals. Since they are both observable and manipulable, such groups are ideal subjects with which to develop and test mathematical models that link the behaviour of small components with the functioning and overall efficiency of their dynamic group-level properties. They provide unrivalled opportunities to quantify the behaviour of individual components within the context of the collective.

This page is more than a wee bit out of date, please see Main and Publications (above) for more up to date information.

 
Collective motion

The integration of individual behaviours within groups such as fish schools leads to a synchrony of motion that is captivating. Similar patterns can be seen in bird flocks, where the volume and shape of the group change as it arcs overhead, yet the aggregate can remain cohesive. We develop individual based models of animal grouping in to investigate how individual behaviours result in collective patterns (including loose 'swarms', collective directional motion and the generation of a 'torus' formation where individuals perpetually rotate around an empty core). This modelling has been useful in revealing theoretical properties of animal groups, including "collective memory", where the previous history of the group structure influences the collective behaviour exhibited as individual interactions change, even though individuals have no knowledge of what that history is. We also explore how behavioural differences among individuals influence the internal structure of such groups, and how individuals using simple, and local, rules can change their spatial position within a group (e.g. to move to the centre, the front, or the periphery) in the absence of their current position within the group as a whole.

We also develop and use new digital imaging techniques to allow many animals to be automatically and concurrently tracked, which is essential to elucidate the link between these levels of organization.

Hensor, E.M.A., Couzin, I. D., James, R. & Krause, J. (2005) Modelling density-dependent fish shoal distributions in the laboratory and the field Oikos 110(2), 344-352.

Couzin, I.D. & Krause, J. (2003) Self-organization and collective behavior of vertebrates Advances in the Study of Behavior 32, 1-75.

Couzin, I.D., Krause, J., James, R., Ruxton, G.D. & Franks, N.R. (2002) Collective memory and spatial sorting in animal groups Journal of Theoretical Biology 218, 1-11.

Croft, D. P., Arrowsmith, B. J., Bielby, J., Skinner, K., White, E., Couzin, I. D., Magurran, A. E., Ranmarine, I. & Krause, J. (2003) Mechanisms underlying shoal composition in the Trinidadian guppy (Poecilia reticulata) Oikos 100, 429-438.

Croft, D. P., Krause, J., Couzin, I. D. & Pitcher, T. J. (2003) When fish schools meet: outcomes for evolution and fisheries Fish and Fisheries 4, 138-146.

Couzin, I.D., Krause, J., James, R., Ruxton, G.D. & Franks, N.R. (2002) Collective memory and spatial sorting in animal groups Journal of Theoretical Biology 218, 1-11.

Ward, A. J. W., Hoare, D. J., Couzin, I. D. & Krause, J. (2002) The effects of parasitism and body length on positioning within wild fish shoals Journal of Animal Ecology 71(1), 10-14.

Collective decision-making and social learning

Animals often move through complex and changing environments where information is distributed in space and time. Each individual, however, can only process and store relatively local information. Aggregates of social animals therefore often consist of individuals that differ with respect to their informational status (such as when only some individuals have pertinent information about the location of a resource), or their internal state (such as degree of hunger). Recently we have shown that when only some individuals within a group have information about a desired direction of travel (such as towards a resource) that the information can be transferred efficiently without signaling and without the group members knowing which individuals have information. Individuals are required only to balance their desired movement with the movement decisions of near neighbours. When informed individuals differ in directional preference, an efficient and accurate consensus can still be made at the group level, despite informed individuals having no knowledge of the relative quality of their information or of whether they are in a majority or minority. Furthermore, the larger the group, the smaller the proportion of informed individuals required to efficiently transfer information.

Dyer, J.R.G., Ioannou, C.C., Piyapong, C., Morrell, L.J., Croft, D.P., Couzin, I.D., Waters, D.A. & Krause, J (2006) Mechanisms and functions of leadership in human groups, in prep.

Couzin, I.D. (2006) Social organization in fission-fusion societies Current Biology 16, 169-171.

Couzin, I.D., James, R., Croft, D.P. & Krause, J. (2006) Social organization and information transfer in schooling fish Fish Learning and Behaviour eds.Brown C., Laland, K.N. & Krause, J., in press.

Couzin, I.D., Krause, J., Franks, N.R. & Levin, S.A.(2005) Effective leadership and decision making in animal groups on the move Nature 433, 513-516.

Press release

LiveScience article

National Geographic News

Hoare, D. J., Couzin, I. D., Godin, J-G. & Krause, J. (2004) Context-dependent group size choice in fish Animal Behaviour 67, 155-164.

Couzin, I.D., Krause, J., James, R., Ruxton, G.D. & Franks, N.R. (2002) Collective memory and spatial sorting in animal groups Journal of Theoretical Biology 218, 1-11.

Locust behaviour

Locusts provide an excellent experimental system to test theories of collective organization since local and principally visually mediated interactions define group behaviours that occur over a very large spatial scale. Much is already known about the physiology and sensory system of locusts and they are very amenable to experimental manipulation. Aggregates of flightless juvenile locust ‘hoppers’ form cohesive and coordinated ‘marching bands’ that can be composed of hundreds of thousands of individuals and extend over tens of kilometers: devastating swarms can invade over 20% of the Earth’s land surface and are estimated to influence the livelihood of one in ten people on the planet. Current control techniques are ineffective, largely due to a poor understanding of where and how hopper bands (and thus ultimately swarms) form and are coordinated (http://www.fao.org).

Bazazi, S, Buhl, J., Hale, J.J., Anstey, M.L., Sword, G.A., Simpson, S.J. & Couzin, I.D. (2008) Collective motion and cannibalism in locust marching bands, Current Biology, in press.

Buhl, J., Sumpter, D.J.T., Couzin, I.D., Hale, J., Despland, E., Miller, E. & Simpson, S.J. (2006) From disorder to order in marching locusts Science 312, 1402-1406.

the above paper was also featured as a Perspectives article in Science, writeen by Daniel Grunbaum:

Grunbaum, D (2006) Align in the sand Science 312, 1320-1322.

Simpson, S.J., Sword A.G., Lorch, P.D & Couzin, I.D. (2006) Cannibal crickets on a forced march for protein and salt. Proceedings of the National Academy of Sciences USA 103, 4152-4156.

Social insects

Ant foraging networks are used to transport resources and/or information during foraging, and also for exploration, emigration and for coordinating colony defence. Just as the functioning and success of modern cities is dependent on an efficient transportation system, the effective management of traffic is essential to insect societies. Furthermore, networks are ubiquitous in nature, and the efficiency of such networks may determine the fundamental scaling properties of certain organisms. The foraging networks of ants provide unrivalled opportunities to quantify both the behaviour of individual items of traffic and larger-scale patterns of traffic flow.

Wrege, P., Wikelski, M., Mandel, J.T. Rassweiler, T & Couzin, I. D. (2005) Antbirds parasitize foraging army ants Ecology 86(3), 555-559.

Couzin, I.D. & Franks, N.R.(2003) Self-organized lane formation and optimized traffic flow in army ants Proceedings of the Royal Society of London, Series B 270, 139-146.

Editor's choice, "Avoiding Gridlock", Science 299, 19

News focus, "Getting the behavior of social insects to compute", Science 295, 2357 article.

"The ants go marching -- and manage to avoid traffic jams", Princeton Weekly Bulletin article.

"Army ants march to military efficiency", New Scientist.

"Army ants obey traffic plan to avoid jams", National Geographic article.

"Ant traffic flow: raiding swarms with few rules avoid gridlock", Science News article.

"Ants offer lessons in urban living", The Guardian

"An urge to organise", The Philadelphia Inquirer.

"Of ants and men: traffic flow", The Today Programme, BBC Radio 4.

"Natural technology", Nature, BBC Radio 4.

"Future watch: ant traffic", Radio South Africa.

Boi, S., Couzin, I. D., Del Buono, N., Franks, N. R. & Britton, N. F. (1999) Coupled oscillators and activity waves in ant colonies Proceedings of the Royal Society Series B 266, 371-378.

Spencer, A. J., Couzin, I. D. & Franks, N. R. (1998) The dynamics of specialization and generalization within biological populations Journal of Complex Systems 1, 114-128.