shaft louse vs bird louse

shaft louse and bird louse both are nouns.

Word	Noun	Adjective	Verb	Adverb
shaft louse	Yes	No	No	No
bird louse	Yes	No	No	No

As nouns, bird louse is a hypernym of shaft louse; that is, bird louse is a word with a broader meaning than shaft louse:

shaft louse: a louse parasitic on poultry
bird louse: wingless insect with mouth parts adapted for biting; mostly parasitic on birds

Other hypernyms of shaft louse include biting louse, louse.

shaft louse (noun)	bird louse (noun)
a louse parasitic on poultry	wingless insect with mouth parts adapted for biting; mostly parasitic on birds