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Providing evidence to improve practice

Action: Exclude or control ‘reservoir species’ to reduce parasite burdens Bird Conservation

Key messages

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  • A literature review found no compelling evidence that culling mountain hares Lepus timidus (a carrier of the ticks that carry louping ill virus) increased red grouse Lagopus lagopus scoticus populations.
  • A controlled before-and-after study from the UK did find that there was a significant increase in chick production on grouse moors with hare culling, compared to control sites but no change in population density. A comment on this paper argued that the controls used in it were not adequate.

 

Supporting evidence from individual studies

1 

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.

Reference

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

 

2 

A 2010 literature review (Harrison et al. 2010) found ‘no compelling evidence’ that culling mountain hares Lepus timidus (a carrier of the ticks that carry louping ill virus) increased red grouse Lagopus lagopus scoticus populations. The authors note that there is some evidence for an effect of culling on the prevalence of louping ill virus (e.g. in Laureson et al. 2003) but that evidence for population-level effects is uncertain, partly due to a lack of understanding of the population dynamics of both hares and grouse.

 

Referenced papers

Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2019) Bird Conservation. Pages 141-290 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.