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.
Number of song recordings with (A) rattles, (B) buzzes, and (C) trills in paired mainland and island species (black bars), also showing the total number of recordings per species (black plus white bars). Mean latitude for each species pair is indicated below the horizontal axis (southern latitudes as negative values).
