Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

The effect of aggressiveness on the population dynamics of a territorial bird


A central issue in ecology lies in identifying the importance of resources, natural enemies and behaviour in the regulation of animal populations. Much of the debate on this subject has focused on animals that show cyclic fluctuations in abundance1,2,3,4,5,6,7. However, there is still disagreement about the role of extrinsic (food, parasites or predators) and intrinsic (behaviour) factors in causing cycles2,8,9,10. Recent studies have examined the impact of natural enemies1,3,4,7, although spatial patterns resulting from restricted dispersal or recruitment are increasingly recognized as having the potential to influence unstable population dynamics5,6,11,12,13. We tested the hypothesis that population cycles in a territorial bird, red grouse Lagopus lagopus scoticus, are caused by delayed density-dependent changes in the aggressiveness and spacing behaviour of males. Here we show that increasing aggressiveness experimentally for a short period in autumn reduced recruitment and subsequent breeding density by 50%, and changed population trajectories from increasing to declining. Intrinsic processes can therefore have fundamental effects on population dynamics.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Changes in grouse numbers on the control (open circles) and testosterone (filled circles) experimental areas of each population.
Figure 2

Similar content being viewed by others


  1. Krebs, C. J. et al. Impact of food and predation on the snowshoe hare cycle. Science 269, 1112–1115 (1995)

    Article  ADS  CAS  Google Scholar 

  2. Stenseth, N. C., Bjornstad, O. N. & Falck, W. Is spacing behaviour coupled with predation causing the microtine density cycle? A synthesis of current process-oriented and pattern-oriented studies. Proc. R. Soc. Lond. B 263, 1423–1435 (1996)

    Article  ADS  CAS  Google Scholar 

  3. Hudson, P. J., Dobson, A. P. & Newborn, D. Prevention of population cycles by parasite removal. Science 282, 2256–2258 (1998)

    Article  ADS  CAS  Google Scholar 

  4. Turchin, P., Taylor, A. D. & Reeve, J. D. Dynamical role of predators in population cycles of a forest insect: An experimental test. Science 285, 1068–1071 (1999)

    Article  CAS  Google Scholar 

  5. Grenfell, B. T., Bjornstad, O. N. & Kappey, J. Travelling waves and spatial hierarchies in measles epidemics. Nature 414, 716–723 (2001)

    Article  ADS  CAS  Google Scholar 

  6. Moss, R. & Watson, A. Population cycles in birds of the grouse family (Tetraonidae). Adv. Ecol. Res. 32, 53–111 (2001)

    Article  Google Scholar 

  7. Korpimaki, E., Norrdahl, K., Klemola, T., Pettersen, T. & Stenseth, N. C. Dynamic effects of predators on cyclic voles: Field experimentation and model extrapolation. Proc. R. Soc. Lond. B 269, 991–997 (2002)

    Article  Google Scholar 

  8. Ostfeld, R. S., Canham, C. D. & Pugh, S. R. Intrinsic density-dependent regulation of vole populations. Nature 366, 259–261 (1993)

    Article  ADS  CAS  Google Scholar 

  9. Berryman, A. A. in Population Cycles: The Case for Trophic Interactions (ed. Berryman, A. A.) 3–28 (Oxford Univ. Press, Oxford, UK, 2002)

    Google Scholar 

  10. Lambin, X., Krebs, C. J., Moss, R. & Yoccoz, N. G. in Population Cycles: The Case for Trophic Interactions (ed. Berryman, A. A.) 155–176 (Oxford Univ. Press, Oxford, UK, 2002)

    Google Scholar 

  11. Lambin, X. & Yoccoz, N. G. The impact of population kin-structure on nestling survival in Townsend's voles, Microtus townsendii. J. Anim. Ecol. 67, 1–16 (1998)

    Article  Google Scholar 

  12. Bjornstad, O. N. & Grenfell, B. T. Noisy clockwork: Time series analysis of population fluctuations in animals. Science 293, 638–643 (2001)

    Article  CAS  Google Scholar 

  13. Blasius, B., Huppert, A. & Stone, L. Complex dynamics and phase synchronization in spatially extended ecological systems. Nature 399, 354–359 (1999)

    Article  ADS  CAS  Google Scholar 

  14. Mountford, M. C., Watson, A., Moss, R. & Parr, R. in Red Grouse Population Processes (eds Lance, A. N. & Lawton, J. H.) 78–83 (British Ecological Society, Ascot, UK, 1990)

    Google Scholar 

  15. Watson, A., Moss, R., Parr, R., Mountford, M. D. & Rothery, P. Kin landownership, differential aggression between kin and non-kin, and population fluctuations in red grouse. J. Anim. Ecol. 63, 39–50 (1994)

    Article  Google Scholar 

  16. Moss, R., Watson, A. & Parr, R. Experimental prevention of a population cycle in red grouse. Ecology 77, 1512–1530 (1996)

    Article  Google Scholar 

  17. Moss, R., Parr, R. & Lambin, X. Effects of testosterone on breeding density, breeding success and survival of red grouse. Proc. R. Soc. Lond. B 258, 175–180 (1994)

    Article  ADS  Google Scholar 

  18. Charnov, E. L. & Finnerty, J. P. Vole population cycles: A case for kin selection. Oecologia 45, 1–2 (1980)

    Article  ADS  CAS  Google Scholar 

  19. Matthiopoulos, J., Moss, R. & Lambin, X. The kin-facilitation hypothesis for red grouse population cycles: Territory sharing between relatives. Ecol. Model. 127, 53–63 (2000)

    Article  Google Scholar 

  20. Hudson, P. J., Newborn, D. & Robertson, P. J. Seasonal and geographical patterns of mortality in red grouse populations. Wildl. Biol. 2, 79–88 (1997)

    Article  Google Scholar 

  21. Hudson, P. J. et al. Trophic interactions and population growth rates: describing patterns and identifying mechanisms. Phil. Trans. R. Soc. Lond. B 357, 1259–1271 (2002)

    Article  Google Scholar 

  22. Thirgood, S. J., Redpath, S. M., Rothery, P. & Aebischer, N. J. Raptor predation and population limitation in red grouse. J. Anim. Ecol. 69, 504–516 (2000)

    Article  Google Scholar 

  23. Dobson, A. P. & Hudson, P. J. Regulation and stability of a free-living host-parasite system—Trichostrongylus tenuis in red grouse. II. Population models. J. Anim. Ecol. 61, 487–498 (1992)

    Article  Google Scholar 

  24. Hudson, P. J., Newborn, D. & Dobson, A. P. Regulation and stability of a free-living host-parasite system—Trichostrongylus tenuis in red grouse. I. Monitoring and parasite reduction experiments. J. Anim. Ecol. 61, 477–486 (1992)

    Article  Google Scholar 

  25. Hudson, P. J., Dobson, A. P. & Newborn, D. in Ecology and Genetics Of Host–Parasite Interactions (eds Rollisson, D. & Andersson, R. M.) 77–89 (Academic, London, UK, 1985)

    Google Scholar 

  26. Fox, A. & Hudson, P. J. Parasites reduce territorial behaviour in red grouse (Lagopus lagopus scoticus). Ecol. Lett. 4, 139–143 (2001)

    Article  Google Scholar 

  27. Folstad, I. & Karter, A. J. Parasites, bright males, and the immunocompetence handicap. Am. Nat. 139, 603–622 (1992)

    Article  Google Scholar 

Download references


We thank the British army, English Nature, and the Dalhousie and Dunecht estates for allowing us access to their moors. We particularly thank T. P. J. Helps, C. McCarthy, J. Adamson, D. Calder and A. Dykes for their help in organizing the fieldwork. We also thank R. Cox, N. Green, D. Luccini and J. Irvine for their help with the fieldwork. D. Elston helped with the statistical analyses. S. Albon, M. Harris, X. Lambin, M. Marquiss, R. Moss and R. Van Der Wal made helpful comments on previous drafts of the manuscript. This work was funded by the Natural Environment Research Council.

Author information

Authors and Affiliations


Corresponding author

Correspondence to F. Mougeot.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Mougeot, F., Redpath, S., Leckie, F. et al. The effect of aggressiveness on the population dynamics of a territorial bird. Nature 421, 737–739 (2003).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing