An Etymological Dictionary of the German Language/Annotated/Sperling
Sperling, masculine, ‘sparrow,’ from the equivalent Middle High German spęrlinc (g), a diminutive of Middle High German spar, Old High German sparo, masculine, ‘sparrow’ (compare English starling, allied to Modern High German Staar), which represents the common Teutonic name of the bird. Compare Gothic sparwa, Old Icelandic spęrr, Anglo-Saxon spearwa, English sparrow (in Dutch mosch, musch; for the Low German term see Lüning). Of this stem sparw-, which is based on the root spor, ‘to sprawl’ (see Sporn), Spatz seems to be a pet form; note also Franconian Sperk, ‘sparrow’ (in Suabian and Bavarian the usual term is Spatz). Compare Sperber.