The Swamp Sparrow is similar in size and habitat to the Song and Lincoln's Sparrows but has rusty wings and lacks extensive dark streaks across the breast. Other sparrows with rusty crowns are paler underneath lacking buffy flanks, rusty wings or blurry streaks on the flanks. Juvenile Swamp Sparrows are very similar to juvenile Lincoln's and Song Sparrows.
Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.