* Differences in genetics: Their DNA is significantly different, preventing successful fertilization.
* Physical incompatibilities: Their reproductive organs are not compatible, making physical mating impossible.
* Behavioral differences: Flying squirrels are nocturnal and arboreal, while regular squirrels are diurnal and live primarily on the ground. These differences make mating unlikely even if they were physically compatible.
Therefore, a flying squirrel cannot mate with a regular squirrel. They are separate species with distinct evolutionary paths.