The Collaborative International Dictionary of English v.0.48:

Tattler \Tat"tler\, n.
   1. One who tattles; an idle talker; one who tells tales.
      --Jer. Taylor.
      [1913 Webster]

   2. (Zool.) Any one of several species of large, long-legged
      sandpipers belonging to the genus Totanus.
      [1913 Webster]

   Note: The common American species are the greater tattler, or
         telltale (Totanus melanoleucus), the smaller tattler,
         or lesser yellowlegs (Totanus flavipes), the solitary
         tattler (Totanus solitarius), and the semipalmated
         tattler, or willet. The first two are called also
         telltale, telltale spine, telltale tattler,
         yellowlegs, yellowshanks, and yelper.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Yellowlegs \Yel"low*legs`\, n. (Zool.)
   Any one of several species of long-legged sandpipers of the
   genus Totanus, in which the legs are bright yellow; --
   called also stone snipe, tattler, telltale,
   yellowshanks; and yellowshins. See Tattler, 2.
   [1913 Webster]

WordNet (r) 3.0 (2006):

yellowlegs
    n 1: either of two North American shorebird with yellow legs