Encyclopedia of Animal Cognition and Behavior

Living Edition
| Editors: Jennifer Vonk, Todd Shackelford


  • Jennifer ColbourneEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-47829-6_621-1



Fear and/or intolerance of strangers, often expressed as aggression or aversion.


Dislike for strangers is pervasive throughout the natural world. The introduction of a strange individual often provokes the strongest aggressive responses in animals; a phenomenon termed the “xenophobic principle” by E. O. Wilson in 1975. Strangers can be a threat to one’s territory, resources, status, or mates, and consequently there is selective pressure against tolerating unknown individuals, as the costs vastly outweigh the benefits (Wilson 1975).

The result is that animals may threaten, harass, or even attack strangers. Animals may go great lengths to avoid areas where strangers may encounter each other; at territory borders, “buffer zones” of increased prey/plant density may be created by such avoidance (Mech 1994). Borders may also be patrolled and marked to ward off intruders, or calls used to advertise the occupation of a...

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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.York UniversityTorontoCanada

Section editors and affiliations

  • Suzanne MacDonald
    • 1
  1. 1.York UniversityTorontoCanada