An Etymological Dictionary of the German Language/wittern
wittern, vb., ‘to scent, spy out,’ from MidHG. witeren, ‘to scent something’; comp. the equiv. OIc. viðra; connected with Wind. “E. to wind, and Fr. vent, ‘scent,’ show that it was possible for the sportsman's phrase to attain this meaning (which is lit. ‘to track by the aid of scent’).”