Behavioral Ecology and Sociobiology

, Volume 22, Issue 2, pp 91–94 | Cite as

Avian flocking reduces starvation risk: an experimental demonstration

  • Jan Ekman
  • Mikael Hake


Theory suggests that variance in individual food intake is lower during group foraging. Consequently, group foraging can at times reduce starvation risk. In aviary experiments using green-finches we demonstrate how intake variability decreases during group foraging because individuals use feeding by flock mates as a cue to locate food (local enhancement). Flocking preferences of greenfinches responded to variance in energy gain as predicted by theoretical models for foragers attempting to reduce starvation risk. While energy budget was positive the greenfinches were risk averse and foraged socially. Their preference shifted towards more risk prone solitary foraging when kept on a negative energy budget. We conclude that time or energy net gains are not necessary for foraging groups to form, but reductions in starvation risk may be sufficient.


Food Intake Theoretical Model Experimental Demonstration Energy Budget Negative Energy 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. Andersson M, Götmark F, Wiklund C (1981) Food information in the Black-headed gull, Larus ridibundus. Behav Ecol Sociobiol 9:199–202Google Scholar
  2. Baker MC, Belcher CS, Deutsch LC, Sherman GY, Thompson DB (1981) Foraging success in junco flocks and the effect of social hierarchy. Anim Behav 29:137–142Google Scholar
  3. Caraco T (1980) On foraging time allocation in a stochastic environment. Ecology 61:119–128Google Scholar
  4. Caraco T (1981) Risk sensitivity and foraging groups. Ecology 62:527–531Google Scholar
  5. Clark C, Mangel M (1984) Foraging and flocking strategies: information in an uncertain environment. Am Nat 123:626–641Google Scholar
  6. Clark C, Mangel M (1986) The evolutionary advantages of group foraging. Theor Pop Biol 30:45–75Google Scholar
  7. Ekman J, Rosander B (1987) Flock size of the social forager: when there is a flocking cost. Theor Pop Biol 31:167–177Google Scholar
  8. Houston A, McNamara J (1982) A sequential approach to risktaking. Anim Behav 30:1260–1261Google Scholar
  9. Houston A, McNamara J (1985) The choice of two prey types that minimises the probability of starvation. Behav Ecol Sociobiol 17:135–141Google Scholar
  10. Houston A, McNamara J (1986) Evaluating the selection pressure on foraging decisions. In: Campan R, Zayan R (eds) Relevance of models and theories in ethology. Privat, I.E.C. Toulouse, pp 61–75Google Scholar
  11. Krebs JR, MacRoberts MH, Cullen JM (1972) Flocking and feeding in the great tit Parus major — an experimental study. Ibis 114:507–530Google Scholar
  12. Krebs JR, Stephens DW, Southerland WJ (1983) Perspectives in optimal foraging. In: Brush AH, Clark GA Jr (Eds) Perspectives in Ornithology. Cambridge, pp 165–221Google Scholar
  13. McNamara J, Houston A (1986) The common currency for behavioural decisions. Am Nat 127:358–378Google Scholar
  14. Pulliam HR (1973) On the advantage of flocking. J theor Biol 38:419–422Google Scholar
  15. Pulliam HR, Millikan GC (1982) Social organization in the non-reproductive season. In: Farner DS, King JR, Parkes KC, (Eds) Avian Biology Vol. VI. Academic Press, New York, pp 169–197Google Scholar
  16. Pyke GH, Pulliam HR, Charnov EL (1977) Optimal foraging: a selective review of theory and tests. Q Rev Biol 52:137–154Google Scholar
  17. Real L, Caraco T (1986) Risk and foraging in stochastic environments. Ann Rev Ecol Syst 17:371–390Google Scholar
  18. Reinertsen RE, Haftorn S (1983) Nocturnal hypothermia and metabolism in the willow tit Parus montanus at 63° N. J Comp Physiol 51:109–118Google Scholar
  19. Schoener T (1971) Theory of feeding strategies. Ann Rev Ecol Syst 2:369–404Google Scholar
  20. Snyderman M (1983) Optimal prey selection: the effect of food deprivation. Behav Anal Lett 3:359–369Google Scholar
  21. Stephens DW (1981) The logic of risk-sensitive foraging preferences. Anim Behav 29:628–629Google Scholar
  22. Stephens DW, Charnov EL (1982) Optimal foraging: some simple stochastic models. Behav Ecol Sociobiol 10:251–263Google Scholar
  23. Thorpe WH (1963) Learning and instinct in animals. Methuen, LondonGoogle Scholar

Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • Jan Ekman
    • 1
  • Mikael Hake
    • 1
  1. 1.Department of ZoologyUniversity of GothenburgGothenburgSweden

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