Behavioral Ecology and Sociobiology

, Volume 26, Issue 1, pp 57–63 | Cite as

Northern harriers on feeding territories respond more aggressively to neighbors than to floaters

  • Ethan J. Temeles


Territory owners often respond less aggressively towards intruding neighbors than towards intruding floaters, an observation termed “the dear enemy phenomenon.” Comparisons of territory owners' responses to intruding neighbors versus their responses to intruding floaters usually have been made for owners of multi-purpose and/or breeding territories. Here, I describe responses of female northern harriers Circus cyaneus (owners) on winter feeding territories towards three types of intruders (female neighbors, female floaters, and male floaters) and show that the dear enemy phenomenon does not occur. Owners' responses towards neighbors were more intense (mostly flights rather than calls) than responses towards female floaters, which in turn were more intense than responses towards male floaters. The greater intensity of owners' responses towards neighbors compared to owners' responses towards male and female floaters may be related to differences in the threat posed by each of the three intruder types in terms of fighting ability (RHP) and potential losses from intrusion. Hence, whether owners respond more aggressively towards neighbors or floaters, and whether the dear enemy phenomenon is observed, may depend upon the relative magnitude of threat presented by neighbors and floaters to owners in terms of fighting ability and potential losses from intrusion.


Relative Magnitude Great Intensity Potential Loss Breeding Territory Fighting Ability 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Altmann J (1974) Observational study of behaviour: sampling methods. Behaviour 49:227–267PubMedGoogle Scholar
  2. Bildstein KL, Collopy MW (1985) Escorting flight and agonistic interactions in wintering northern harriers. Condor 87:398–401Google Scholar
  3. Brodsky LM, Montgomerie RD (1987) Asymmetrical contests in defense of rock ptarmigan territories. Behav Ecol Sociobiol 21:267–272Google Scholar
  4. Carpenter FL (1987) The study of territoriality: complexities and future directions. Am Zool 27:401–409Google Scholar
  5. Cramp S, Simmons KEL (1980) Handbook of the birds of Europe, the Middle East, and north Africa, vol. II. Oxford Univ Press, OxfordGoogle Scholar
  6. Dixon WJ, Brown MB, Engelman L, Frane JW, Hill MA, Jennrich RI, Toporek JD (1983) BMDP statistical software. Univ California Press, BerkeleyGoogle Scholar
  7. Falls JB (1969) Functions of territorial song in the white-throated sparrow. In: Hinde RA (ed) Bird vocalizations. Cambridge Univ Press, Cambridge, pp 207–232Google Scholar
  8. Fienberg SE (1970) The analysis of multidimensional contingency tables. Ecology 51:419–433PubMedGoogle Scholar
  9. Fisher JB (1954) Evolution and bird sociality. In: Huxley J, Hardy AC, Ford EB (eds) Evolution as a process. George Allen and Unwin, Ltd., London, pp 71–83Google Scholar
  10. Gass CL (1979) Territory regulation, tenure, and migration in rufous hummingbirds. Can J Zool 57:914–923Google Scholar
  11. Getty T (1987) Dear enemies and the prisoner's dilemma: why should territorial neighbors form defensive coalitions? Am Zool 27:327–336Google Scholar
  12. Getty T (1989) Are dear enemies in a war of attrition? Anim Behav 37:337–339Google Scholar
  13. Hansen AJ (1986) Fighting behavior in bald eagles: a test of game theory. Ecology 67:787–797Google Scholar
  14. Jenkins SH (1975) Food selection by beavers: a multidimensional contingency table analysis. Oecologia (Berlin) 21:157–173Google Scholar
  15. Krebs JR (1976) Habituation and song repetoires in the great tit. Behav Ecol Sociobiol 1:215–227Google Scholar
  16. Krebs JR (1982) Territorial defense in the great tit (Parus major): do residents always win? Behav Ecol Sociobiol 11:185–194Google Scholar
  17. Maynard Smith J (1982) Evolution and the theory of games. Cambridge Univ Press, CambridgeGoogle Scholar
  18. Neter J, Wasserman W (1974) Applied linear statistical models. Richard D. Irwin, Inc., HomewoodGoogle Scholar
  19. Parker GA (1974) Assessment strategy and the evolution of fighting behavior. J Theor Biol 47:223–243Google Scholar
  20. Parker GA, Rubenstein DI (1981) Role assessment, reserves strategy, and aquisition of information in asymmetric animal conflicts. Anim Behav 29:221–240Google Scholar
  21. Pennycuick C (1972) Animal flight. Edward Arnold, LondonGoogle Scholar
  22. Riechert SE (1978) Games spiders play: behavioral variability in territorial disputes. Behav Ecol Sociobiol 3:135–162Google Scholar
  23. Siegel S (1956) Nonparametric statistics. McGraw-Hill, New YorkGoogle Scholar
  24. Temeles EJ (1986) Reversed sexual size dimorphism: effect on resource defense and foraging behaviors of nonbreeding northern harriers. Auk 103:70–78MathSciNetzbMATHGoogle Scholar
  25. Temeles EJ (1987) The relative importance of prey availability and intruder pressure in feeding territory size regulation by harriers, Circus cyaneous. Oecologia (Berlin) 74:286–297Google Scholar
  26. Temeles EJ (1989a) The effect of prey consumption on territorial defense by harriers: differential responses to neighbors versus floaters. Behav Ecol Sociobiol 24:239–243Google Scholar
  27. Temeles EJ (1989b) Effect of prey consumption on foraging activity of northern harriers. Auk 106:353–357Google Scholar
  28. Toft CA (1984a) Resource shifts in bee flies (Bombyliidae): interactions among species determine choice of resources. Oikos 43:104–112Google Scholar
  29. Toft CA (1984b) Activity budgets of two species of bee flies (Lordotus: Bombyliidae, Diptera): a comparison of species and sexes. Behav Ecol Sociobiol 14:287–296Google Scholar
  30. Ydenberg RC, Giraldeau LA, Falls JB (1988) Neighbors, strangers, and the asymmetric war of attrition. Anim Behav 36:343–347Google Scholar

Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • Ethan J. Temeles
    • 1
  1. 1.Department of ZoologyUniversity of TennesseeKnoxvilleUSA

Personalised recommendations