An Etymological Dictionary of the German Language/Sperling
Sperling, m., ‘sparrow,’ from the equiv. MidHG. spęrlinc (g), a dimin. of MidHG. spar, OHG. sparo, m., ‘sparrow’ (comp. E. starling, allied to ModHG. Staar), which represents the common Teut. name of the bird. Comp. Goth. sparwa, OIc. spęrr, AS. spearwa, E. sparrow (in Du. mosch, musch; for the LG. 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 Franc. Sperk, ‘sparrow’ (in Suab. and Bav. the usual term is Spatz). Comp. Sperber.