Then ascertain, positively and absolutely, when the last attack of disease occurred; it will be the year after the last successful season.
Then take the moor for a term of years, ending in the seventh year from the date of the disease year.
Those moors that suffer the most in their disease year, like the moor in Strathspey, referred to in Season 1871, will probably afford the heaviest shooting in their good years.
Grouse, of course, have other drawbacks besides disease.
If the moors are on high ground, they are liable to have eggs frosted in late frosts, or young grouse killed by late snowstorms, as occurred in Season 1864 on Glenshee. Again, you may have a lazy, whiskey drinking keeper, who neglects vermin-killing; but, as a rule, once out of the egg, the young bird is safe.
[ Heather Burning and Draining.]
Indiscriminate burning of heather is another great drawback on Sutherland and Caithness moors.
In Caithness, it will take fourteen or more years to grow deep, good heather on the hill moors, and in Sutherland eight or ten.
The upper moors of Caithness, and also of parts of Sutherland, carry very little really good heather; in fact, only on the burn banks or dry knolls does it grow.