Individual study: Possible reductions in louping ill virus in a red grouse Lagopus lagopus scoticus population following mountain hare Lepus timidus control
Laurenson M.K., Norman R.A., Gilbert L., Reid H.W. & Hudson P.J. (2003) Identifying disease reservoirs in complex systems: mountain hares as reservoirs of ticks and louping‐ill virus, pathogens of red grouse. Journal of Animal Ecology, 72, 177-185
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Exclude or control ‘reservoir species’ to reduce parasite burdens
A controlled before-and-after study in the Scottish Highlands between 1993 and 2001 (Laurenson et al. 2003) found that there was no significant increase in the population density of red grouse Lagopus lagopus scoticus at a site with mountain hare Lepus timidus (a carrier of the ticks that carry louping ill virus) culling, compared to a control site without hare culling (approximately 25 grouse/km2 in 1993 and 100/km2 in 2001 at the experimental site vs. 140/km2 and 275/km2 at the control). However, there was a significant increase in the number of chicks produced/female at the treatment site, compared to the control (approximately 1.2 chicks/female in 1991 and 5 in 2001 at the experimental site vs. 3.5 and 3.0 at the control) and a significant reduction of louping ill virus at the treatment site, compared to a second control site. Hare densities were reduced from 8/km2 in 1993 to 0 in 1998. A comment on this paper in 2004 (Cope et al. 2004) argues that the control sites were not adequate, as they differed in either the pre-existing incidence of louping ill virus or in various environmental conditions.
Cope, D. R., Iason, G. R. & Gordon, I. J. (2004) Disease reservoirs in complex systems: a comment on recent work by Laurenson et al. Journal of Animal Ecology, 73, 807–810