Yeah I checked back on them this morning and there's some kind of white sticky goo they're very into! Despite the really cold and wet weather. I still need to find out the tree species. It's a garden plant my parents put in decades ago.

More video! This is like 6 hours later than the first one

Entomology folks, wasp people, what is up with these yellow jackets? They've been clustered here and feeding (?) for at least the last couple hours. This is the Bay area.