What is a female fox called?

It is called a vixen

A female fox is called a vixen. (This term is sometimes used to refer to an attractive young woman who exhibits flirtatious behavior.)

A female fox is called a vixen. Male foxes are called reynards; and baby foxes are pups or kits. Groups of kits are called litters.
a vixen
A female fox is called a vixen.
A vixen.