Letter | Published:

Parasites and climate synchronize red grouse populations


There is circumstantial evidence that correlated climatic conditions can drive animal populations into synchronous fluctuations in abundance1,2,3,4,5. However, it is unclear whether climate directly affects the survival and fecundity of individuals, or indirectly, by influencing food and natural enemies. Here we propose that climate affects trophic interactions and could be an important mechanism for synchronizing spatially distributed populations. We show that in specific years the size of red grouse populations in northern England either increases or decreases in synchrony. In these years, widespread and correlated climatic conditions during May and July affect populations regionally and influence the density-dependent transmission of the gastrointestinal nematode Trichostrongylus tenuis, a parasite that reduces grouse fecundity6. This in turn forces grouse populations into synchrony. We conclude that specific climatic events may lead to outbreaks of infectious diseases or pests that may cause dramatic, synchronized changes in the abundance of their hosts.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Cattadori, I. M., Merler, S. & Hudson, P. J. Searching for mechanisms of synchrony in spatially structured gamebird populations. J. Anim. Ecol. 69, 620–638 (2000)

  2. 2

    Grenfell, B. T. et al. Noise and determinism in synchronized sheep dynamics. Nature 394, 674–677 (1998)

  3. 3

    Post, E. & Forchammer, M. C. Synchronization of animal population dynamics by large-scale climate. Nature 420, 168–171 (2002)

  4. 4

    Ranta, E., Kaitala, V., Lindström, J. & Lindén, H. Synchrony in population dynamics. Proc. R. Soc. Lond. B 262, 113–118 (1995)

  5. 5

    Stenseth, N. C. et al. Common dynamic structure of Canada lynx populations within three climatic regions. Science 285, 1071–1073 (1999)

  6. 6

    Hudson, P. J., Dobson, A. P. & Newborn, D. Population cycles and parasitism. Science 286, 2425a (1999)

  7. 7

    Bjørnstad, O. N., Peltonen, M., Liebhold, A. M. & Baltensweiler, W. Waves of larch budmoth outbreaks in the European Alps. Science 298, 1020–1023 (2002)

  8. 8

    Ranta, E., Kaitala, V., Lindström, J. & Helle, A. The Moran effect and synchrony in population dynamics. Oikos 78, 136–142 (1997)

  9. 9

    Moran, P. A. P. The statistical analysis of the Canadian lynx cycle. II. Synchronization and meteorology. Austr. J. Zool. 1, 291–298 (1953)

  10. 10

    Greenman, J. V. & Benton, T. G. The impact of stochasticity on the behaviour of nonlinear population models: synchrony and the Moran effect. Oikos 93, 343–351 (2001)

  11. 11

    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)

  12. 12

    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)

  13. 13

    Cattadori, I. M., Haydon, D. T., Thirgood, S. J. & Hudson, P. J. Are indirect measures of abundance a useful index of population density? The case of red grouse harvesting. Oikos 100, 439–446 (2003)

  14. 14

    Haydon, D. T., Shaw, D. J., Cattadori, I. M., Hudson, P. J. & Thirgood, S. J. Analysing noisy time series: describing regional variation in the cyclic dynamics of red grouse. Proc. R. Soc. Lond. B 269, 1609–1617 (2002)

  15. 15

    Hudson, P. J. Grouse in Space and Time (The Game Conservancy Trust, Fordingbridge, 1992)

  16. 16

    Buonaccorsi, J. P., Elkinton, J. S., Evans, S. R. & Liebhold, A. M. Measuring and testing for spatial synchrony. Ecology 82, 1668–1679 (2001)

  17. 17

    Haydon, D. T., Greenwood, P. E., Stenseth, N. C. & Saitoh, T. Spatio-temporal dynamics of the grey-sided vole in Hokkaido: identifying coupling using state-based Markov-chain modelling. Proc. R. Soc. Lond. B 270, 435–445 (2003)

  18. 18

    Hudson, P. J. The effect of a parasitic nematode on the breeding production of red grouse. J. Anim. Ecol. 55, 85–94 (1986)

  19. 19

    Anderson, R. C. Nematode Parasites of Vertebrates. Their Development and Transmission 2nd edn (CABI, Wallingford, 2000)

  20. 20

    Lee, D. L. The Biology of Nematodes (Taylor and Francis, London, 2002)

  21. 21

    Marquardt, W. C., Demaree, R. S. & Grieve, R. B. Parasitology and Vector Biology (Harcourt Academic, San Diego, 2000)

  22. 22

    Slagsvold, T. Production of young by the Willow Grouse Lagopus lagopus (L.) in Norway in relation to temperature. Norw. J. Zool. 23, 269–275 (1975)

  23. 23

    Mougeot, F., Redpath, S. M., Leckie, F. & Hudson, P. J. The effect of aggressiveness on the population dynamics of a territorial bird. Nature 421, 737–739 (2003)

  24. 24

    Watson, A., Moss, R. & Parr, R. Effect of food enrichment on numbers and spacing behaviour of red grouse. J. Anim. Ecol. 53, 663–678 (1984)

  25. 25

    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)

  26. 26

    Shipley, B. Cause and Correlation in Biology (Cambridge Univ. Press, Cambridge, 2000)

  27. 27

    Pugesek, B. H., Tomer, A. & von Eye, A. Structural Equation Modeling (Cambridge Univ. Press, Cambridge, 2003)

  28. 28

    Hudson, P. J., Dobson, A. P. & Newborn, D. in Population Cycles (ed. Berryman, A.) 109–129 (Oxford Univ. Press, Oxford, 2003)

  29. 29

    Hudson, P. J. & Dobson, A. P. in Infectious Diseases in Natural Populations (eds Grenfell, B. T. & Dobson, A. P.) 144–176 (Cambridge Univ. Press, Cambridge, 1995)

Download references


I.M.C. thanks D. Shaw for statistical advice. We are also grateful to D. Newborn of the Game Conservancy Trust, The Earl Peel and moor owners in northern England who allowed us to aggregate the database. O. Bjørnstad, E. Post and D. Johnson provided comments on an earlier version. I.M.C. was funded by a Marie Curie fellowship.

Author information

Correspondence to Isabella M. Cattadori.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Supplementary information

Supplementary Information

Includes: supplementary text, supplementary tables 1-3, supplementary reference. (DOC 142 kb)

Rights and permissions

Reprints and Permissions

About this article

Further reading

Figure 1: Locations of the 91 red grouse populations that provided annual harvesting records between 1839 and 1994.
Figure 2: Spatio-temporal patterns of synchrony between populations within each of the five regions.
Figure 3: Simplified path diagram with parameterized path coefficients of simulated interactions between climate, parasites and red grouse.


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.