Here's what Teasedale-Buckell has to say on the matter:
Capercailzie
This is the finest game bird we have, unless it be considered
that the lately introduced wild turkeys are finer ; both are the
offspring of imported birds, for the turkeys never were British
birds, and the capercailzie after extinction were re-introduced
in the Taymouth Castle district by the then Earl of Breadalbane.
The birds do not grow in Scotland to nearly the size of those
of the Continent, and fine as they are they give but little sport, and are thought to be objectionable in many ways. One of
these is said to be that they eat the leaders of the Scotch pine
and so ruin the trees ; but it is difficult to believe this to be
correct, for the leaders of the pines could hardly be reached from any other branch but its own, and this would prove a very
insecure seat for so heavy a bird. However, capercailzie are
increasing in Scotland, in spite of the determination of many
woodmen to keep them down. That they form a very pretty
addition to a day's bag, and create the excitement that variety
usually affords, is true enough. There is no place equal to some
of the less elevated estates in Perthshire for variety of bag.
There capercailzie, roe deer, brown hares, rabbits, duck, teal,
blackcock, pheasants, grouse, partridges, woodcock, two sorts
of snipe, and wood pigeons, as well as a variety of the scarcer
kinds of duck, may all be killed in one day. But it is difficult
to beat for the majority of these varieties of game in any one
way ; for instance, capercailzie and black game seem to require
special methods of beating covers for them, and then they are
not both likely to take the same course, as the caper can make but little headway up hill and the black game can. Where
capercailzie are numerous they are very interesting to drive and
shoot, for it is not easy to do either properly. But they are
usually too scarce for special days in October, and in August
they give no sport in their half-fledged condition. Seventy of
these birds have been killed in driving in one day near Dunkeld.
The hens lay from 6 to 13 eggs. The full-grown cock-ofthe-
woods weighs from 9 to 1 3 lbs. in Scotland, but is bigger
in Scandinavia. The hen lays late in May, and the birds are
polygamous. Linnaeus gave the scientific name Tetrao urogallus
to the cock-of-the-woods, which is known in Gaelic as Capultcoille. He is Tiwr to the Norwegian, and Tjader to the Swede; Glouhar to the Russian, and Auerhahn to the German. These
birds became extinct in Ireland about 1760 and in Scotland
about 1780, and were not re-introduced successfully until 1837,
although repeated attempts had been made.
From "The Complete English Wing Shot", 1907