Falcons can be a real issue especially during spring and early summer when they are nesting. I'm speaking about here in the US and primarily Peregrine Falcons and Prairie Falcons. They generally nest on the side of cliffs (Peregrines also on high rises in the bigger cities). They will aggressively dive bomb other larger birds that come anywhere near their nests, so you may want to be cautious when flying in those areas. They are about the size of a crow or a little larger and are very capable of taking ducks on the wing so a MP should be no issue for them if they feel threatened. Merlins are a smaller falcon but I have observed them on several occasions dive bombing crows just for the sake of harassment so they could present a minor problem, but again they are much smaller and I don't think they could do much damage to a MP since they don't go into the high speed stoops as the Prairies and Peregrines do. Golden Eagles could pose a real threat also. My experience with raptors stems from being a Master Falconer for 28 years.