I think the mockingbird seeks to intimidate rivals by appearing to be a multitude of birds.
But when you listen to them, it’s hard not to think that they may be singing for the sheer joy of it.
Tom played a video of a kookaburra on his iPod for Kathleen. She was very amused. “Elk sounds” is still her favorite, though.
When we lived in the desert, the mockingbirds used to sit on top of any tall structure and do a crazy, hoppy dance while singing the most extensive variety of songs I’ve ever heard. I videotaped them for 45-minute periods.