This video from the USA says about itself:
Male Ruby-crowned Kinglet Snacks On Suet In West Texas – Dec. 9, 2019
A male Ruby-crowned Kinglet stops by the feeders in West Texas for an early morning snack. Smaller than a warbler or chickadee, these tiny passerines are known for constantly flicking their wings as they flit through the bushes. Males hide a ruby crown that gets flashed when they’re excited. Can you see the ruby feathers hidden on this bird’s crown as he pecks away in front of the camera?