An Etymological Dictionary of the German Language/Annotated/Schwalbe
Schwalbe, feminine,‘swallow,’ from the equivalent Middle High German swalwe, Old High German swalawa, feminine; a common Teutonic term; corresponding to the equivalent Dutch zwaluw, Anglo-Saxon swealwe, English swallow, Old Icelandic svala (genitive svǫlu), feminine, ‘swallow.’ No certain explanation can be given of the primary form swalwôn, feminine; perhaps it represents swalgwôn-, pre-Teutonic swalkuân, to which Greek ἀλκύων is also traced.