I spied some Dark-eyed Juncos and a Cardinal couple going to town on some seeds under a tree. And it looks like a White-breasted Nuthatch was there too, flexing and trying to get the cardinal to back off. I thought it was a junco too, but the head is too dark (with just a hint of white on the sides) and the wings are too patterned.
It’s neat, though, I’ve never seen this behaviour in little songbirds. But I guess you want to protect your turf no matter your size.