CLOSED: Strange bird on my Bluebird Eggs!

I just came in from checking my bluebird boxes. When I approached one of them, a bird with white stripes on its head peeked from the hole. Thinking a different bird was nesting in the box, I tapped the box to run her out so I could check the nest. It held four bluebird eggs! So, now I am worried that the bird was a visitor to the box. It definitely wasn't a cowbird or a house sparrow. It was the size of a bluebird, but it flew too quickly for me to get a better look.......other than the white stripes on its grayish head.

I hope some of you experts will chime in here. I don't know what to do! Surely, the bluebirds will run off an interloper, but I didn't see either parent around. The box is too far from the house for me to keep an eye on it for very long.

Or maybe I just let Nature takes its course........

I don't know what to think about that.

Could it have been a House Wren; that would be bad news.

There is a type of sparrow that has white stripes on it's head. We had one at our house last night, but I can't think of the name of it right off.

Well, you've got your white crowned sparrow and your white throated sparrows. They are both stripy. I have not heard that they are a predator or nest competitor though.

I'm going to have DH go with me tomorrow to check the box........and eggs. (I'm really worried about those eggs!) If that bird is still in the box, maybe we can identify it. DH said he thought he'd seen a Downy come out of that box last week.

Maybe we just have really friendly birds around here.........

Did you have any success in seeing the bird again Mima?