Disease control on grouse moors

TickQ: What veterinary interventions are used on grouse moors?
A: Diseases are controlled in livestock (most often sheep) and in red grouse on moors. In both animals the parasites controlled are internal worms and external blood-sucking ticks. Though the two species share the same tick species, the internal worms they have are different.

Q: Why are ticks a problem?
A: The sheep or deer tick (Ixodes ricinus) found on sheep also feed on red grouse and other moorland birds, to whom they can pass a virus called the louping-ill virus (LIV). LIV disease can cause up to 80% mortality in red grouse chicks.

Q: What is done about this?
A: The number of ticks that are present in a given area can be reduced by limiting the number of hosts – a very long-term approach – or treating the hosts. Sheep have been treated with anti-tick medication (acaricides) for over 50 years for their own health. To reduce the number of ticks on moorland, generally the sheep need to be dipped once or twice more than usual in the summer. The GWCT has developed and continues to research new methods of tick control. If a large population of deer are providing an additional host and inflating the tick population, deer numbers can be reduced on the moor.

Q: Are these treatments dangerous?
A: No. The medication that is used to reduce ticks on sheep that graze moors is the same as that used on sheep farms across the country.

Q: Do these ticks also affect humans?
A: Yes. Ticks also bite humans, and our dogs, where they can be a vector for the Borrelia parasite that causes Lyme disease. This can be very serious if not diagnosed and treated.

Q: What about other moorland birds?
A: Ticks also feed on other moorland birds. Although it appears that waders such as curlew do not contract LIV, excessive tick burden has been cited as a cause of mortality for curlew chicks. It is known that high numbers of ticks attached around the face can be debilitating for the chicks of moorland birds. In one study 91% of curlew broods contained chicks carrying ticks at an average of 4.5 ticks per chick, and a maximum of 64 ticks on one individual.

Q: What else is administered to the animals on grouse moors?
A: Upland sheep and red grouse suffer from different parasitic worm infections, though the chemicals used to treat them are the same. Sheep are regularly treated throughout the year against a range of gut parasites to prevent loss of condition and poor lambing. In red grouse the most important disease (strongylosis) is caused by the strongyle worm and has a similar effect, reducing survival and breeding performance. Historically, strongylosis has driven grouse population cycles, with crashes in red grouse numbers as a result of this disease every few years. If strongylosis is affecting the birds on a moor, medicated grit can be provided under the supervision of a veterinarian. This controls the parasite, improving the survival and breeding performance of the grouse population.

Grit box
Medicated grit to control strongyle infection is provided in grit trays, which can be closed as
necessary to prevent or allow access when appropriate. Use is prescribed by a veterinarian.

Q: Are all moors distributing this medicated grit all the time?
A: No. Use is regulated and it is only provided when the birds need it, when prescribed by a vet. Typically demonstrating need involves the moor collecting sample worm burden data from grouse to test for worm numbers.

Q: What effects could the grit be having on the environment or other species?
A: The active ingredient that is applied to the grit is called flubendazole, which is an anti-nematode (worming) agent that is given to livestock across the country in far greater quantities than would ever be present on a moor. As a licensed medication, it has passed thorough investigations into the effect on non-target species, as well as the wider environment.

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