Current address: Division of Environmental and Evolutionary Biology, University of Glasgow G12 8QQ, UK.
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The shape of red grouse cycles
Article first published online: 16 JUN 2004
DOI: 10.1111/j.0021-8790.2004.00853.x
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How to Cite
Shaw, D. J., Haydon, D. T., Cattadori, I. M., Hudson, P. J. and Thirgood, S. J. (2004), The shape of red grouse cycles. Journal of Animal Ecology, 73: 767–776. doi: 10.1111/j.0021-8790.2004.00853.x
Publication History
- Issue published online: 16 JUN 2004
- Article first published online: 16 JUN 2004
- Received 4 August 2003; accepted 14 January 2004
- Abstract
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Keywords:
- asymmetry;
- cycle shape;
- Lagopus lagopus scoticus;
- red grouse;
- time reversibility;
- time-series analysis
Summary
- 1We examined 223 time-series of red grouse (Lagopus lagopus scoticus) numbers compiled from shooting bag-records from grouse moors located across England, Scotland and Wales for evidence of non-time-reversibility, asymmetry in cycle shape and non-linearity.
- 2We found 44% of time-series to be non-time-reversible. Over 80% of time-series spent more time increasing than decreasing (but only 32% did so significantly).
- 3Non-linearity was detected in 44% of time-series examined, and these non-linear time-series were 1·7 times more likely to be non-time-reversible compared to the linear time-series.
- 4The occurrence of non-linear and non-time-reversible series was not related to location, number of days with rain, temperature, moor area or population growth rate. The predominance of symmetrical peaks increased with easting but was not related to number of days with rain, temperature, northing or moor area.
- 5There were no significant relationships between time-reversibility or non-linearity status and either tendency to cycle or cycle periodicity. However, populations that cycled with longer periods exhibited slower rates of increase and more equal lengths of time increasing and decreasing in numbers.
- 6Our results provide little evidence that grouse cycles observed in different parts of the species range in the United Kingdom arise from fundamentally different processes.