The Collaborative International Dictionary of English v.0.48:

Red-tailed \Red"-tailed`\ (-t?ld`), a.
   Having a red tail.
   [1913 Webster]

   Red-tailed hawk (Zool.), a large North American hawk
      (Buteo borealis). When adult its tail is chestnut red.
      Called also hen hawck, and red-tailed buzzard.
      [1913 Webster]