Antipredator benefits of schooling behaviour in a cyprinodontid fish, the banded killifish (Fundulus diaphanus)

Fish schools are believed to provide antipredator benefits to their members. Two potential antipredator benefits, the dilution and confusion effects, of schooling were investigated in the laboratory using banded killifish (Fundulus diaphanus). Individual risk of being attacked and killed by a fish predator (white perch, Morone americana) declined with increasing killifish school size in a manner closely predicted by the dilution hypothesis. Perch were apparently not confused by schooling killifish since fish in groups of one did not suffer a disproportionately greater predation rate than fish in all larger school sizes. However, killifish straggling from the school were preferentially attacked and more successfully captured compared with school members. Schooling in the banded killifish therefore confers a considerable antipredator benefit to individual group members, at least through a dilution effect, and straying from a school has an associated increased risk of mortality to predation, which selects for schooling behaviour.

[1]  R. C. Miller.  The Significance of the Gregarious Habit , 1922 .

[2]  Osamu Ohguchi,et al.  Prey density and selection against oddity by three-spined sticklebacks , 1981 .

[3]  G. Wilkinson,et al.  PREDATION AND COLONIALITY IN CLIFF SWALLOWS (PE TR 0 CHELID ON PYRRHONO TA ) , 1982 .

[4]  W. Hamilton.  Geometry for the selfish herd. , 1971, Journal of theoretical biology.

[5]  J. Bédard,et al.  Gull Predation and Creching Behaviour in the Common Eider , 1977 .

[6]  P. F. Major,et al.  Predator-prey interactions in two schooling fishes, Caranx ignobilis and Stolephorus purpureus , 1978, Animal Behaviour.

[7]  K. R. Mckaye,et al.  Comments on the breeding biology of Gobiomorus dormitor (Osteichthyes : Eleotridae) and the advantage of schooling behavior to its fry , 1979 .

[8]  T. Pitcher,et al.  Predator-avoidance behaviours of sand-eel schools: why schools seldom split , 1983 .

[9]  W. Foster,et al.  Group transmission of predator avoidance behaviour in a marine insect: The trafalgar effect , 1981, Animal Behaviour.

[10]  G. Potts.  The predatory tactics of Caranx melampygus and the response of its prey , 1983 .

[11]  W. Foster,et al.  Evidence for the dilution effect in the selfish herd from fish predation on a marine insect , 1981, Nature.

[12]  L. Brower,et al.  Mortality of the Monarch Butterfly (Danaus plexippus L.): Avian Predation at Five Overwintering Sites in Mexico , 1979, Science.

[13]  P. Duncan,et al.  The effect of group size in horses on the rate of attacks by blood-sucking flies , 1979, Animal Behaviour.