Extrinsic factors influencing the population dynamics of red grouse. Lagopus lagopus scoticus
1995
Hudson, P.J. | Dobson, A.P.
Our long term population studies of Red Grouse have concentraded on the relative importance of different natural enemies throughout the geographic range of this subspecies. The parasitic nematode Trichostrongylus tenius reduces the survival and breeding production of Red Grouse and these effects are sufficient to generate long-term cycles in grouse abundance. Predator populations on moorlands, especcially red foxes in Scotland, have increased over the past 30 years. Parasites tend to cause morbidity and increase the vulnerability of grouse predators. Mathematical models demonstrate that the removal of heavily infected grouse individuals by a small number of predators may allow the size of the red grouse population to increase because the predators effectively reduce the regulatory role of the parasites. However, moderate and high levels of predation result in suppression of the Red Grouse population through predation
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