"Keep off! This is my turf!" The True Song is given by males to declare territory. Neighboring males are stressed by the song -- their heart rates increase and they stay away. At the same time that the song warns away other males, it entices females near.
Peek and Tut
"Heads up!" Given by males and females, especially during the nesting season, this is a low-grade alarm call. It means potential predators have been spotted. Listen for 2-3 sharp "peek!" calls alternating with softer "tut" calls.
