wader vs wading bird

wader and wading bird both are nouns.

Word	Noun	Adjective	Verb	Adverb
wader	Yes	No	No	No
wading bird	Yes	No	No	No

As nouns, wader and wading bird are synonyms defined as:

wader and wading bird: any of many long-legged birds that wade in water in search of food

wader (noun)	wading bird (noun)
any of many long-legged birds that wade in water in search of food	any of many long-legged birds that wade in water in search of food