The Pine Siskin can be identified by its yellow patches in the wings and tail. When these are not visible, as on a perched bird, it can look like a sparrow. It is smaller than sparrows and lacks a pale supercilium.
Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.