Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Sonograms of experimental playback sounds: (a) a long aerial alarm call (‘trill’), and (b) a short ground alarm call (‘buzz’). The short aerial alarm call and long ground alarm-call playbacks are not illustrated, but differed only in duration and not element type (§2). Spectrograms were created using a filter bandwidth of 699.4 Hz, frame length of 256 points, and the grid resolution set to 21.53 Hz and 1.45 ms.
