Complex sentence: Clefairy are difficult to spot, due to the fact it can only be found in certain areas, infrequently, however, they seem to be much more common on the night of a full moon.
Split into simpler sentences: Clefairy are difficult to spot, due to the fact that they can only be found in certain areas, infrequently. However, they seem to be much more common on the night of a full moon.