Ah, there is indeed a word, 'oiselle' which originally referred to a female bird, but it is very rarely used in this sense today. You'll find it referring to a silly and naive girl. Not very common , though as people tend to be a bit more blunt today.
Another word is somtimes used with the same meaning and referrence to birds: une bécasse.
And finally, you also have 'une oie blanche' which describes a sexually naive and inexperienced bécasse.