bird vs birder

bird and birder both are nouns.

Word	Noun	Adjective	Verb	Adverb
bird	Yes	No	Yes	No
birder	Yes	No	No	No

bird (noun)	birder (noun)
warm-blooded egg-laying vertebrates characterized by feathers and forelimbs modified as wings	a person who identifies and studies birds in their natural habitats
badminton equipment consisting of a ball of cork or rubber with a crown of feathers
a cry or noise made to express displeasure or contempt
the flesh of a bird or fowl (wild or domestic) used as food
informal terms for a (young) woman

bird (verb)	birder (verb)
watch and study birds in their natural habitat