Threat posture

For a very small bird waxeyes  have a lot of attitude - if they spent as much time eating as they do asserting themselves - to no obvious good purpose - they'd be a lot less hungry. They stand out on the branches vibrating their wings and trying to look 5x their actual size.

Back blip of Lindis Pass in the snow
https://www.blipfoto.com/entry/2866554519280419571