I recently had a similar issue with a goose. I'd try to take them out when she's away and candle them, just to be sure, then take it from there. You'll find other posts here on how to candle if you don't know how. They'll just eventually rot and "explode", and get stink and grossness all over and on momma. Plus, it's kinda hard on the females to sit for extremely long times. They don't get out and about too much to eat, etc.. They can be so dedicated, can't they?

Lisa and Cathy, Thanks for your encouragement. This year, the nest box is where I don't have but a few steps to run down should I have to :) Plus, I've had my knee replaced since last summer so I'm doing steps MUCH better. But the bottom line is THERE WILL BE NO HOUSE WRENS! I put a sign up where they can see it so I expect it'll work...I WISH! So far so good. I have two babies who are growing fast. And they are tough kids so there's nothing could stop them!! Bluebird blessings, Linda...

Very odd things happening with my houses this year. I had bluebirds in one house that laid 5 eggs. For the most part I try to stay away so they don't get spooked. In this case the next time I checked there was one fledgling that I saw but he didn't seem ready to fly away yet. But when I checked 2 days later there were no babies or eggs. The nest was empty. This box was protected with the mesh on the opening. I'm hoping time just flew by and the brood hatched and fledged in my absence! Will the parents start a new brood in the same nest or should I clean the box out for them to start over? I had another box that had activity, 5 eggs layed and a week later no eggs or babies. I fear they were killed since it was an old house from last year and it did not have the protective metal mesh at the opening. I have a nest nearby with the mesh protection. I kept checking and there was no activity or eggs. Then suddenly there was one egg!! I assumed the mom would lay more. I checked for 2 days, still only one egg. The third day the egg hatched with a tiny bald with a little fuzz baby bird. I kept watching from a distance and I did not see the male or female going into the house. I skipped looking inside the box today. I wanted to stay totally away. Tomorrow I will check again. I hope the little guy is okay.... Is it unusual for a female to lay only one egg? I'm thinking that perhaps the pair that were in the other box moved to this box when a predator got their other eggs..... Thus only one last egg to lay??? The box with the one egg is about 20 feet from the empty box. Perhaps this is part of that brood? Can the mom or dad move an egg or did she just lay it in a different box?? I have another box about 100 feet from that one protected with the mesh that some sparrows have taken over. They have built a nest and hang out in front of it on the mesh opening and on top of it but no eggs for well over a month. Perhaps they are the culprits that got the 5 bluebird eggs. Very strange that they built a nest and aren't using it. I know they will build several, one as a decoy or to give the female a choice, but I don't see that they've done that unless they are planning to take over the bluebird box. I will be keeping a watch on that....

What mlkbskt said is correct. A nestbox should never be mounted on a fence/tree or post of any kind unless it can be baffled. Conduit works best for mounting nestboxes on and stovepipe baffles are cheap and easy to put up. Nestboxes should also be put up at least 15 feet away from any trees. With just one egg gone I would think either House wren (are they in Texas?) or House Sparrow. The House Sparrow will usually just go in and smash the eggs and or kill babies and adults that may be in the box, however it could have gotten interrupted by the Bluebirds too. That is why a sparrow spooker is very important to put up after the first egg is laid. Sparrow spookers are easily accepted by Bluebirds. Wren guards are a little trickier though but do help if wrens are in the area. It is best to put them up during egg laying though to make sure they are accepted. The whiter end and ring on the egg is normal, I have seen it before too. A mockingbird would not be able to get into the nestbox so it would not have taken the egg. Is the hole on your nestbox the 1 1/2 inches that is standard for the Bluebird nestboxes? It shouldn't be larger to prevent Starlings or Red Bellied Woodpeckers from reaching in and grabbing eggs or babies. As far as the heat, I know it can kill nestlings if it gets too hot but not sure about affecting hatching, normally the Momma just wouldn't need to incubate as much. Day 15 is not out of the norm, I have heard of eggs going up to 20 days and still hatching. So the eggs can still be good, but if something got one chances are it could come back and get the rest. Raccoons love to reach into nestboxes and pull out babies/eggs and incubating female but they usually do it at night so the momma would be gone/eaten and probably all the eggs if it were a raccoon. Raccoons are everywhere even if you don't see them, they are there! I would keep a close eye on the Blues and see what they are doing. Are they still going to the box or not? Usually they will not give up on the nest if an egg is taken like that, so the nesting should still be ok and also they can sit on eggs a long time before they give up on them. Good luck, hopefully you can get this nestbox safe and can have a successful second nesting. Don't let the first nesting fool you since it was successful, an improperly mounted nestbox is a failure just waiting to happen. Read up at sialis like you said you were, there is tons of great info on there! Donna