Common Buzzard?

I guess this is just a Common Buzzard and the dark secondaries may be a result of covert moult? it is an adult that has been on this territory for at least two years and I have always jokingly said the Swainson's Hawk is up again -- just how different are pale morph Swainson's from this bird though? saw a lot in Alberta this year but as usual failed to grill them properly en route to something else! terrible pics in heat haze at great height