the lighter side of Short-eared Owls

Of 13+ birds present just two seem to be dark birds but they are both the tame ones -- this sort of ratio seems to be what I have observed in big concentrations in past winters with 1 dark to 5-6 light birds -- according to BWP the richer buff birds are females; ageing birds relies on seeing the pattern of t1 which suggests that this pale bird is a first-winter male;
Concentrations of birds occur where food is abundant in winter with birds sometimes holding individual winter territories; in Manitoba an average territory size of 6.3 hectares is quoted in BWP -- at this site there is 130 hectares of stewardship but some of it is very wet so adding the rough ground on drain edges would probably produce a total of 150 hectares of suitable hunting; thus the total of 13 birds seen at one time may well be below the total number present --
What is strange is that the 3 Hen Harriers that were wintering all seem to have disappeared (although one was seen briefly this week) and given the abundance of food this seems odd

As usual the Kestrels were taking several voles from the owls and I suspect that the large number of Carrion Crows and Magpies are raiding the vole larders made by the owls as two I checked had no voles present the day after I watched 6 voles stashed --
Watching birds should always encourage us to think more about our subject