Bushtit parent tends to the chicks

I found this great little nest hanging fairly low in a tree. I can't imagine how much work that must have been for these tiny birds and now after they've built their mansion, the little ones are keeping them quite busy running back and forth bringing in little bugs and taking out waste. The dark eyes tell me this is the harried little father, but I could hear that the chicks were active and both parents were dashing in and out. In fact there may have been more than just two. Bush tits are sometimes observed to be either cooperative breeders with helpers or possibly even polyandrous (females having more than one male mate).