The effects of acaricide treatment of sheep on red grouseLagopus lagopus scoticatick burdens and productivity in a multi‐host system

Abstract

Ixodes ricinus (Ixodida: Ixodidae) ticks are of economic and pathogenic importance across Europe. Within the uplands of the U.K., management to reduce ticks is undertaken to benefit red grouse Lagopus lagopus scotica (Galliformes: Phasianidae). Management strategies focus on the acaricide treatment of domestic sheep Ovis aries (Artiodactyla: Bovidae), but the effectiveness of this is less certain in the presence of wild hosts, particularly red deer Cervus elaphus (Artiodactyla: Cervidae) and mountain hare Lepus timidus (Lagomorpha: Leporidae). This study examines the effects of sheep management on grouse tick burdens and productivity using sites with a range of wild host densities. Sites at which applications of acaricide were more frequent had lower tick burdens; this relationship was similar on sites with a range of deer densities. However, no direct link was detected between acaricide treatment interval and grouse productivity. Sites with higher deer densities had higher grouse tick burdens and lower productivity [mean ± standard error (SE) young : adult ratio: 1.2 ± 0.2] compared with sites with lower deer densities (mean ± SE young : adult ratio: 1.8 ± 0.1). Sites with higher grouse brood sizes and higher proportions of hens with broods were also those with higher mountain hare abundance indices. This study highlights the importance of the frequent treatment of sheep with acaricide to reduce tick burdens on grouse, even in the presence of wild hosts.

Seven decades of mountain hare counts show severe declines where high‐yield recreational game bird hunting is practised

“…If culling of hares in an attempt to reduce LIV in grouse has driven the severe declines seen since 1999, as seems a parsimonious explanation, then it is important also to recognise that there is no evidence that the culls increase either red grouse densities (Harrison et al., ) or chick survival (Fletcher, ). Indeed, in a recent study of the effect of acaricidal treatment of sheep on red grouse tick burden and breeding productivity, Fletcher and Baines () noted that grouse productivity and local mountain hare abundance were positively rather than inversely correlated. Elsewhere, culling as a means of disease reduction or improvement of economic returns also has a poor track record of success across taxa as diverse as Yellowstone bison Bison bison , European badger Meles meles , and Tasmanian devil Sarcophilus harrisii as well as mountain hare (e.g., Beeton & McCallum, ; Harrison et al., ; Vial & Donnelly, ; White, Wallen, Geremia, Treanor, & Blanton, ).…”

Sheep tickIxodes ricinusmanagement on Welsh hill farms of designated conservation importance: implications for nationally declining birds

“…A comparison of tick infestation rates on sheep and red grouse chicks from this study with other studies in the U.K. in relation to whether acaricide treatment of sheep was 'standard' (typically two applications per year) or had been 'improved' (four applications per year). (Fletcher & Baines, 2018) 2012-13 Improved -(24) 5.8 (0.3-23.2) North York Moors (Newborn & Baines, 2012) 1992-99 Standard -(9) 11.2 (6.4-19.9) 1995-03 Improved -(11) 1.8 (0.1-6.7) North York Moors (Newborn et al, 2014) 2012-13 Standard (2) 5.2 (3.5-6.9) -Improved…”

“…England (Newborn & Baines, 2012;Newborn et al, 2014, Baines & Taylor, 2016Fletcher & Baines, 2018). In the latter regions, improved acaricide management of hill sheep flocks was associated with a significant reduction in tick burdens of both grouse chicks (Newborn & Baines, 2012) and sheep (Newborn et al, 2014), which in turn was associated with higher grouse chick survival, productivity and post-breeding densities (Baines & Taylor, 2016; D. Baines, Unpublished data).…”

“…In northern England, an increased frequency of acaricide applications to domestic sheep has reduced tick parasitization of grouse chicks, leading to higher post‐breeding densities within a simple sheep‐grouse host system (Newborn & Baines, ). In the Scottish uplands, where the system is complicated by wild red deer Cervus elaphus and mountain hare Lepus timidus forming alternative large mammalian hosts, culls of these wild hosts, in conjunction with introducing acaricide‐treated sheep flocks, have also been associated with both increased red grouse breeding success and densities (Fletcher & Baines, ; D. Baines, Unpublished data). Deer, both red and roe Capreolus capreolus , are few in North Wales, whereas mountain hare are absent; thus, the host system is similar to that in northern England.…”

Five ixodid tick species including two morphotypes of Rhipicephalus turanicus on nestlings of Eurasian eagle owl (Bubo bubo) from south-eastern Bulgaria

“…However, not only migratory birds are important tick hosts, as resident species may serve as high-density hosts [ 15 ], especially in the case of bird species feeding or breeding on the ground [ 16 ]. Papers reporting tick parasitism of resident populations are usually targeting one or a few host species, with game birds [ 17 ] and seabirds [ 18 ] being the most common groups studied, but the ecology of bird-specialist ticks is also well documented in passerines [ 19 , 20 ]. Owls (Strigiformes) are rarely studied as tick hosts, due to their scarcity, nocturnal habits or hard-to-access nesting sites [ 21 ].…”