They are not mules. They are hybrids. Frowned upon by
those who appreciate pure bloodlines, and are against
creating new mutations. Mainly because the lines are muddied
and color combinations not as striking on the norm.
However, it's happened in natural as well as controlled
environments for many years. Nobody has proven that these
combinations are not able to produce their own offspring.
Masked and Fischers have been put together by many.
What do you plan to do with the babies? Will you continue to
allow them to colonize and breed with the rest?