Peekaboo

There was a small group of these tiny birds flitting about in the tree for a short time. Unfortunately, they didn't stay still for very long, making them hard to find and focus on, and they had a tendency to stay high in the tree, so only a view from underneath was possible. Ah well, such is life. I'm not sure what bird this is, so any wise owls out there, I'd be grateful for your input. Thank you.