Is it not the St Kildale sheep are quite a famous scientific study population.
I can't remember the exact details now as 25+ yes ago and mind pickled with bevy in those days,
But from memory the sheep have 2 different coat types, 1 tends to be sheep with shorter teeth and the other coat type tends sheep with longer teeth.
They have monitored the population and % of each coat type for decades now.
The % are always changing but broadly speaking tended to follow the same patterns.
When populations low the coat type which favours longer teeth would be highest % , as can handle the longer grass better= is fitter.
But as population increases the coat type for shorter teeth would rise as it could handle the shorter grass conditions better so it was fitter/ producing more young.
Then population would crash throu starvation and it all starts again.
If I mind right was uite a classic cyclic population and with the added bonus of the coat type ideticating tooth size.
And has been self regulating for decades,.
But unless something else has changed ie big increase in deer numbers or possibly even big increase in visitor numbers disturbing sheep on the lower better grazing land and pushing them higher up slopes on to poorer grazinI'
But im sure in the past they were self regulating, if u started to cull them it could render decades of scientific population studies void, or atleast going forward
I'm sure mungo on here could explain it properly, as it isa bit vague now.
But I can remember it being quite interesting all those years ago