Selfish HerdStudies have shown that the chances of an individual being eaten during a predator attack decrease as the number of individuals they are surrounded by increases. This idea, named the selfish herd by William Donald Hamilton, is typically used in evolutionary biology courses when explaining grouping behaviors. Hawks and falcons are considered the biggest predators of starlings, so murmurations are often considered to be a continuous movement towards the center of the murmuration in order to be in the most safe position. Because of the great amount of movement done by the starlings, the center of the flock is never able to stabilize, resulting in the murmuration perpetually twisting and turning as a result of the continuous escape motions.
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Many scientists, however, do not believe that murmurations are purely the result of a selfish herd. Though the starlings may be trying to avoid predators, murmurations draw great amounts of attention to the starlings, causing predators to be more successful in finding the starlings than they would be if the starlings did not perform such stunts.
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Information Transfer Within Animal GroupsResearch from the 1970's suggests that starlings that are part of larger groups responded faster to the presence of predators than those in smaller groups. Along with this, research shows that the 'waves' of the murmuration are linked to lessened success in predation by falcons. Since there is no local structure in the waves, the waves are likely to confuse predators, resulting in their lessened success. The idea is that the information concerning the predator is shared throughout the group, allowing for the majority of the population to be more likely to survive. In other forms of collective motion, this information may help allow a group of animals to find a food source or find a good place to sleep for the night. This information transfer, therefore, provides a very basic evolutionary explanation for the origin of different forms of collective motion.
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References
Hamilton, W. (n.d.). Geometry for the selfish herd. Journal of Theoretical Biology, 295-311.
King, A., & Sumpter, D. (n.d.). Murmurations. Current Biology, 22(4), R112-R114. doi:10.1016/j.cub.2011.11.033
King, A., & Sumpter, D. (n.d.). Murmurations. Current Biology, 22(4), R112-R114. doi:10.1016/j.cub.2011.11.033
Multimedia Sources
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Header Image: https://c2.staticflickr.com/6/5171/5429758700_8f8b9b0c21_b.jpg
First Image: http://www.learningedges.com/wp-content/uploads/2015/03/Murmuration-of-Starlings.jpg
Second Image: http://blog.allaboutbirds.org/wp-content/uploads/2013/02/starlings.jpg
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