mammal vs female mammal

mammal and female mammal both are nouns.

Word	Noun	Adjective	Verb	Adverb
mammal	Yes	No	No	No
female mammal	Yes	No	No	No

As nouns, female mammal is a hyponym of mammal; that is, female mammal is a word with a more specific, narrower meaning than mammal:

mammal: any warm-blooded vertebrate having the skin more or less covered with hair; young are born alive except for the small subclass of monotremes and nourished with milk
female mammal: animals that nourish their young with milk

mammal (noun)	female mammal (noun)
any warm-blooded vertebrate having the skin more or less covered with hair; young are born alive except for the small subclass of monotremes and nourished with milk	animals that nourish their young with milk