Bunting scored his as F# minor, but used natural signs on all of the D's to correct to the proper mode (making it dorian). Niel Gow's (where he notes that it is a reel) is in D minor.

Bunting in general used major or minor scoring modes as the basis for his tunes, then used accidentals to correct to other modes. That's not terribly uncommon, but you have to look at the whole tune, not just the keynote and signature to find out what the mode really is. Note also that the mode is not always a given. Some tunes are found in several modes.