Commentary for Genesis 8:18

ויצא נח, the fact that the Torah, in this verse, separates the females from the males, may hint that the females were afraid to leave the ark until after the males had left and assured themselves and them that it was possible again to live outside the ark.

ויצא נח ובניו, “Noach and his sons left the ark, etc.” Some commentators claim that although marital relations between the sexes had been permitted again, the manner in which the Torah writes the males exiting from the ark as if in a group is revealing. On the other hand, the Talmud in Sanhedrin 108 states that there were three creatures which violated the prohibition of sexual relations during their stay in the ark: the dog, the raven and Noach’s son Cham. All of them were punished for their misconduct. The dog is tied by a chain or leash to its owner. The raven is forced to spit after indulging in mating, and Cham’s skin, or that of his offspring, turned black.