How did Adam know the animals were male and female?

According to the biblical account in the book of Genesis, when God created the animals, He created them "according to their kinds" (Genesis 1:24-25). It is possible that Adam observed the distinctive physical characteristics of the animals, such as their reproductive organs or behaviors, and recognized that they belonged to different sexes. Additionally, it is also possible that God revealed this knowledge to Adam as a part of his role as the steward and caretaker of creation. Therefore, Adam was able to recognize the animals as male and female.