Thanks guys, I followed your advice and removed the egg. I made a home-made hole reducer out of a piece of cardboard and taped it inside the box to the front of the box. It's been taped to the hole from all angles. Hoping it will hold up. It is a 1 1/4" or as close as I could get eyeballing it. The chickadees accepted it after a few minutes. Cardboard was the only thing I could think of that is flexible yet sturdy since I have gilbertson boxes. Crossing my fingers for no cowbird attacks. Never had a cowbird egg in 13 years of backyard birding, but now my 1st year at my new house and 1st nest of chickadees ever, I get one.

There is a park, a small field that is regularly mowed, and a sort of a wet-weather slough that runs between four properties (one of which is ours). It's basically what's left when a developer is too lazy to properly landscape when they build a plat on uneven terrain. There may be only one of the females; We've been away for awhile and I've not yet seen her again since we got back. Apparently my female house sparrows have lost their itty-bitty minds and have taken to scattering the seed from the window feeder far and wide, which has finally given the grackles something they can get at. The grackles are making things a little more difficult for everyone else and I wonder if they've driven her off. So I'll not be filling the window feeder any more - then we'll see if Ms. RWBB comes back or no, LOL!

GoldfinchGuy, Great success story. I am happy a brood of yours fledged. Please share your story on bluebird nut cafe. It is a much more popular forum than this one. I come here to help and answer questions but some I cannot answer so I tell them to post their story there. I would love to hear more about your trail and it's results this season. Please join us at the link below http://bluebirdnutcafe.yuku.com/ -Tyler

So far I've only seen cowbird babies here with Red-winged Blackbirds and Baltimore Orioles. The size is similar and there seem to be mixed families so the cowbirds don't appear to have displaced the original babies. The red-wings and cowbirds feed together amicably and the orioles brought both cowbird and oriole fledglings to the jam feeders (although the cowbirds didn't eat the jam). None of the cardinals, blue jays, or grackles have cowbirds associated with them, so they probably rejected them. No crows either, although they're fledging now and the adult cowbirds are probably long gone. I can't imagine a crow putting up with a cowbird chick, anyway. I wonder if the cowbird fledglings identify with the birds that raised them, so that a cowbird female raised by a red-wing would be more likely to lay an egg in a red-wing nest. That should give a higher rate of success and maybe skew the egg-laying process toward species like red-wings and orioles. Claire