The Collaborative International Dictionary of English v.0.48:

Merl \Merl\, Merle \Merle\, n. [F. merle, L. merula, merulus.
   Cf. Ousel.] (Zool.)
   The European blackbird. See Blackbird. --Drayton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

merle
    n 1: common black European thrush [syn: blackbird, merl,
         merle, ouzel, ousel, European blackbird, Turdus
         merula]