Mom has been spying on the wrens who built their nest in one of our window boxes. She sent me these pictures, and the following:

The five babies were heaped up like puppies, all asleep, and all yellow beak. I saw both parents feeding the babies yesterday -- peanut butter, I think. Doesn't seem like good baby food to me, but it would have lots of protein!

The wrens (which mate for life) brood the eggs for about two weeks. Then they feed their young til they fledge in about two weeks. In another month they're on their own (assuming they survive -- 20% is a good rate, the bird folks say), and the next spring, they're ready to set up their own families.