An Etymological Dictionary of the German Language/Annotated/wittern
wittern, verb, ‘to scent, spy out,’ from Middle High German witeren, ‘to scent something’; compare the equivalent Old Icelandic viðra; connected with Wind. “E. to wind, and French vent, ‘scent,’ show that it was possible for the sportsman's phrase to attain this meaning (which is literally ‘to track by the aid of scent’).”