the species is difficult indeed, certainly 'our' subspecies. The pic is taken in the east of Belgium where both short-toed and eurasian breed. Short-toed is a common breeder all over Belgium, Eurasian (macrodactyla) only breeds the east and the south. the nominate of Eurasian is a rarity in Belgium (mostly near the coast). The macrodactyla subspecies of Eurasian is in this context more difficult to recognise. I have noticed before that the coloration on the wing coverts is in some way variable, in my opinion (things that are also easier to see in the field) short-toed should have greyer underparts contrasting with the whitish throat, more brownish wash on the rear flanks, less contrast between outer and inner web of tertials, less rufous upper tail,... so i'm pretty sure this is a Eurasian. I'm happy to send other pics of the bird if needed.