Source : Webster's Revised Unabridged Dictionary (1913)

Yelper \Yelp"er\, n.
   An animal that yelps, or makes a yelping noise. Specifically:
   (Zo["o]l.)
   (a) The avocet; -- so called from its sharp, shrill cry.
       [Prov. Eng.]
   (b) The tattler. [Local, U. S.]