Proto-cooperation: Group hunting sailfish improve hunting success by alternating attacks on grouping prey (2016)
Authors
Abstract
We present evidence of a novel form of group hunting. Group hunting sailfish (Istiophorus platypterus) alternate attacks on their schooling prey (Sardinella aurita). While only 23% of attacks result in prey capture, multiple prey are injured in 95% of attacks, resulting in an increase of injured fish in the school with the number of attacks. How quickly prey are captured is positively correlated with the level of injury of the school, suggesting that hunters can benefit from other conspecifics' attacks on the prey. To explore this, we built a mathematical model capturing the dynamics of the hunt. We show that group hunting provides major efficiency gains (prey caught per unit time) for individuals in groups of up to 70 members. We also demonstrate that a free riding strategy, where some individuals wait until the prey are sufficiently injured before attacking, is unlikely to be beneficial. This form of group hunting provides evidence that cooperative benefits can be realised through the facilitative effects of individuals' hunting actions without spatial coordination of attacks. Such 'proto-cooperation' may be the pre-cursor to more complex group-hunting strategies.
Bibliographic entry
Herbert-Read, J. E., Romanczuk, P., Krause, S., Strömbom, D., Couillaud, P., Domenici, P., Kurvers, R. H. J. M., Marras, S., Steffensen, J. F., Wilson, A. D. M., & Krause, J. (2016). Proto-cooperation: Group hunting sailfish improve hunting success by alternating attacks on grouping prey. Proceedings of the Royal Society of London: B, Biological Sciences, 283:20161671. doi:10.1098/rspb.2016.1671 (Full text)