Mountain hares, louping‐ill, red grouse and harvesting: complex interactions but few data

First paragraph: Our recent paper examined the impact of a large-scale fieldmanipulation of mountain hare density on the dynamics of ticks, louping-ill andred grouse (Laurenson et al. 2003). We found that hares were an important hostfor ticks and for the transmission of louping-ill, and that tick burdens andlouping-ill seroprevalence in grouse declined when hare densities were reduced,in comparison to a control. In addition, the number of young grouse produced peradult bird increased, but no effect on grouse density was found. Our model ofthe system showed that the dynamical decline in louping-ill can be accounted forthrough the decline of both ticks and the process of non-viraemic transmission.Cope, Iason & Gordon (2004) make two broad sets of observations on this study.First, they comment on the limitations of the controls. Secondly, they makeminor modifications to an existing model of nematode-driven grouse cycles,replicating previously published research (Hudson et al.2002) and use it toconfirm the same finding that louping-ill virus may be expected to dampen grousecycles. Combined, the authors use these observations to argue that a policy ofreducing mountain hare density to keep grouse moors economically viable has notbeen proven and go on to imply that louping-ill may even improve the economicsof grouse harvesting