Schools of fish and flocks of birds: Their shape and internal structure by self-organization

Charlotte K. Hemelrijk*, Hanno Hildenbrandt

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

111 Citations (Scopus)
152 Downloads (Pure)

Abstract

Models of self-organization have proved useful in revealing what processes may underlie characteristics of swarms. In this study, we review model-based explanations for aspects of the shape and internal structure of groups of fish and of birds travelling undisturbed (without predator threat). Our models attribute specific collective traits to locomotory properties. Fish slow down to avoid collisions and swim at a constant depth, whereas birds fly at low variability of speed and lose altitude during turning. In both the models of fish and birds, the 'bearing angle' to the nearest neighbour emerges as a side-effect of the 'blind angle' behind individuals and when group size becomes larger, temporary subgroups may increase the complexity of group shape and internal structure. We discuss evidence for model-based predictions and provide a list of new predictions to be tested empirically.

Original languageEnglish
Pages (from-to)726-737
Number of pages12
JournalInterface Focus
Volume2
Issue number6
DOIs
Publication statusPublished - 6-Dec-2012

Keywords

  • self-organization
  • shape of a group
  • flock of birds and school of fish
  • internal structure
  • locomotion
  • collective motion
  • INDIVIDUAL-BASED MODEL
  • TAIL BEAT FREQUENCY
  • 3-DIMENSIONAL STRUCTURE
  • ANIMAL GROUPS
  • EMERGENT PROPERTIES
  • PREDATORS ATTACK
  • STURNUS-VULGARIS
  • DECISION-MAKING
  • STARLING FLOCKS
  • PREY-FLOCK

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