Audubon's warbler vs Audubon warbler

Audubon's warbler and Audubon warbler both are nouns.

Word	Noun	Adjective	Verb	Adverb
Audubon's warbler	Yes	No	No	No
Audubon warbler	Yes	No	No	No

As nouns, Audubon's warbler and Audubon warbler are synonyms defined as:

Audubon's warbler and Audubon warbler: common warbler of western North America

Other synonyms of Audubon's warbler include Dendroica auduboni.

Audubon's warbler (noun)	Audubon warbler (noun)
common warbler of western North America	common warbler of western North America