Collective Decision Making: Synchronous movement Of individuals in groups

1. Collective Decision Making: Synchronous movement Of individuals in groups Emily McHenry Biology 478 April 25, 2012

2. What Is Collective Behavior? http://www.youtube.com/watch?v=Ua2quxUDyRk&feature=related (Start at 3:37)

3. What Is Collective Behavior? Collective animal behavior: the coordinated behavior of large groups of similar animals and the emergent properties of these groups (Couzin 2012). worldhum.com

4. Examples of collective behavior • Flocks of birds • Swarms of insects • Schools of fish • Herds of mammals aquariumprosmn.com digital-photography-school.com esa.org

5. Why do animals move synchronously? • Increased foraging efficiency (Bazazi 2012) • Energy efficiency (Tamm 1980) • Aerodynamic and hydrodynamic benefits • Predation avoidance • Relies on selfish herd effect; increased group size results in lower chances of any one individual becoming a victim

6. Predation Avoidance • There are 3 Distinct patterns of predation avoidance • Vacuolization: • where expansion results in a cavity forming around the predator • Flash expansion: • where individuals rapidly move away from the predator as it strikes • Split effect • where the group fragments • Most common reason for aggregations, but not always beneficial! • http://www.youtube.com/watch?v=XzZhSl_00pI&feature=related

7. Studying Collective Behavior • Most research has been done in two ways: • Filming groups and then frame-by-frame analyzing • Swarm simulating software princeton.edu

8. Swarm simulations • Swarms are created following 3 fundamental rules: • Separation: steer to avoid crowding or collisions • Alignment: steer toward the average heading of groupmates • Cohesion: steer to move toward the average position of local groupmates http://www.youtube.com/watch?v=GUkjC-69vaw

9. How do animals move synchronously? • Previously thought to be telepathic • Utilizing senses • Eyesight, pressure, hearing, etc. • Monitoring position of neighbors • Behavioral zones • Repulsion • Attraction • Alignment based on relative position

10. Decision Making in the group • Flocking Birds/Schooling Fish • Democracy • Quorum responses (Sumpter 2009) • Insects • No leader, forced march (Simpson 2006) • Mammals • Unknown

11. Questions?

12. Works cited • Potts, Wayne K. 1984. "The chorus-line hypothesis of coordination in avian flocks." Nature 24: 344-345. • Simpson, Stephen J, Gregory A. Sword, Patrick D. Lorch, and Iain D. Couzin. "Cannibal Crickets on a Forced March for Protein and Salt." Proceedings of the National Academy of Sciences of the United States of America. 103.11 (2006): 4152-4156. • Bazazi, S. et al. (2012) Vortex formation and foraging in polyphonic spadefoot toad tadpoles. Behavioral Ecology and Sociobiology. March 2012. • Tamm, Staffan. "Bird Orientation: Single Homing Pigeons Compared with Small Flocks." Behavioral Ecology and Sociobiology. 7.4 (1980): 319-322. • Tien, J Rubenstein, D. “Dynamics of fish shoals: Identifying key decision rules.” Evolutionary Ecology Research, No. 6. (2004), pp. 555-565 • Ward, A.J.W, D.J.T Sumpter, I.D Couzin, P.J.B Hart, and J Krause. "Quorum Decision-Making Facilitates Information Transfer in Fish Shoals." Proceedings of the National Academy of Sciences of the United States of America. 105.19 (2008): 6948-6953. • Sumpter, D.J.T, and S.C Pratt. "Quorum Responses and Consensus Decision Making." Philosophical Transactions of the Royal Society B: Biological Sciences. 364.1518 (2009): 743-753. • Couzin, I D, and J Krause. "Self-organization and Collective Behavior in Vertebrates." Advances in the Study of Behavior. 32 (2003): 1-75. • Couzin, I. D., J. Krause, R. James, G. D. Ruxton, and N. R. Franks. 2002. Collective memory and spatial sorting in animal groups. Journal of Theoretical Biology 218: 1-11. • Caraco, T., S. Martindale, and H. R. Pulliam. 1980. Flocking: advantages and disadvantages. Nature 285: 400-401.