Proto-cooperation: group hunting sailfish improve hunting success by alternating attacks on grouping prey.
We present evidence of a novel form of group hunting. Individual sailfish (Istiophorus platypterus) alternate attacks with other group members on their schooling prey (Sardinella aurita). While only 24% 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 only beneficial if the cost of attacking is high, and only then when waiting times are short. Our findings provide evidence that cooperative benefits can be realized 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.
Department of Mathematics, Uppsala University, 75106, Uppsala, Sweden james.herbert.read@gmail.com.|Department of Zoology, Stockholm University, 10691, Stockholm, Sweden.
James E
0000-0003-0243-4518
JE
Herbert-Read
Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin, Germany.|Faculty of Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany.|Department of Ecology and Evolutionary Biology, Princeton University, Princeton 08544, NJ, USA.
Pawel
P
Romanczuk
Department of Electrical Engineering and Computer Science, Lübeck University of Applied Sciences, 23562 Lübeck, Germany.
Stefan
S
Krause
Department of Mathematics, Uppsala University, 75106, Uppsala, Sweden.|Department of Biology, Lafayette College, Easton 18042, PA, USA.
Daniel
D
Strömbom
Département de la Licence Sciences et Technologies, Université Pierre et Marie Curie, 75005 Paris, France.
Pierre
P
Couillaud
IAMC-CNR, Istituto per l'Ambiente Marino Costiero, Consiglio Nazionale delle Ricerche, Località Sa Mardini, 09170 Torregrande, Oristano, Italy.
Paolo
0000-0003-3182-2579
P
Domenici
Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin, Germany.|Center for Adaptive Rationality, Max Planck Institute for Human Development, 14195 Berlin, Germany.
Ralf H J M
RH
Kurvers
IAMC-CNR, Istituto per l'Ambiente Marino Costiero, Consiglio Nazionale delle Ricerche, Località Sa Mardini, 09170 Torregrande, Oristano, Italy.
Stefano
S
Marras
Marine Biological Section, University of Copenhagen, Helsingor 3000, Denmark.
John F
JF
Steffensen
School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales 2006, Australia.|School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia.
Alexander D M
AD
Wilson
Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, Berlin, Germany.|Faculty of Life Sciences, Humboldt-Universität zu Berlin, 10115 Berlin, Germany.
Jens
0000-0002-1289-2857
J
Krause
D000818:Animals; D003299:Cooperative Behavior; D005399:Fishes; D010473:Perciformes / Q000502:physiology*; D011235:Predatory Behavior
Istiophorus platypterus; cooperation; group hunting; proto-cooperation; sailfish