Sounds like you really have some challenges. You have my sympathies! A tiny poked hole is more likely a house wren's thin sharp beak, sometimes taking them some distance away, or simply tossing them out. The house sparrow will toss the eggs out, but their finch-like beak would not as likely make a tiny poke hole. And the HOSP is more likely to stick around, harass, or even take over the cavity. "Do BB's destroy their own eggs" ... No "the nest possibly could have been flooded?" ... are there leaks that could be fixed? "Are the HOSP really sneaky" ... yes, but HOWR are sneakier ... "and resistant to the Sparrow Spooker?" ... yes, and house wrens will not be deterred by a sparrow spooker. House Wrens are even sneakier, faster and silent, leaving no evidence behind, only destroying eggs or young. You might hear them singing, but might never, ever see them! There are some links to sound files of house wren song and chatter on Bet's web pages, so you can learn to hear the unwelcome sounds of house wrens. Visit Bet's web page for more info. And by the way, the Carolina Wren is a very different bird, welcome almost anywhere; not a threat to other birds. BlueBars Here is a link that might be useful: http://www.sialis.org/index.html

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.

That smaller egg is definitely a Cowbird egg. I got in a HEAP of trouble a few weeks back when I was trying to get some advice on this subject (see the reg. birding forum under "Cowbird Egg in Finch Nest - probably on about pg. 3 by now, for the fracas...), so tread very carefully. I - how shall I say - "took care of" the egg in question. Only you can choose what to do with your interloper egg, but be ready to get flamed by most of the GW birding world for your "illegal, unethical, criminal, (et al)" behavior if you mention it here.

My guess is they are cowbird eggs. Very gently remove the brown speckled eggs (as not to crack the bb eggs) they will hatch before the bluebird eggs do and will eventually take over the nest box and the baby blues probably will not survive. I get them in the poor chipping sparrows nest and the cowbird babies are bigger than the nest. The chipping sparrow eggs are thrown out of the nest by the baby cowbirds. Karen