What is "telltale spine"

Tattler \Tat"tler\, n.

1. One who tattles; an idle talker; one who tells tales.
   --Jer. Taylor.

2. (Zo["o]l.) Any one of several species of large, long-legged sandpipers belonging to the genus Totanus.

   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.