Does a Sitting Bird Still Hum?

Landing

A female hummingbird has claimed sole ownership of our hummingbird feeder. She is a militaristic guardian of her territory, attacking all other hummers. She first drinks deeply from the nectar, then lands on the hook and just sits for long stretches at a time, always watching the skies for intruders to attack.  Some of her "dog fights" are quite vicious, actually slamming into the other bird and locking onto her victim and not letting go until they almost hit the ground.  I think she should run for Congress.

On Guard

Don't even think about approaching me!

Sticking out her tongue... Pthhh!