I am pretty new at this myself, but have a 2nd brood with the 5th egg laid today. Last year was my 1st year, and I lost five babies to a cat or coon because I didn't know not to have the nesting box on a cedar post. It didn't have a baffle on it. So sad. Anyway ...

I think your babies are in jeopardy if your nesting boxes are attached to a fence. Others on this forum will tell you that too. Do you have them protected with a stove pipe baffle or conduit? Do you have a sparrow spooker and wren guard on the houses? I had all of that in place this year, and successfully fledged five babies. Hoping that my 2nd brood will be as successful, as there are wrens in the area and the wren guard isn't a guarantee.

Not sure about the heat, but it could be a wren took that egg. House wrens are nasty birds. Hopefully, Donna will respond to your questions. Welcome to blue birding and GOOD LUCK with your 2nd nesting.

Thanks for the info. No I don't have a baffle, conduit, sparrow spooker, or wren guard. I am new at this and didn't know I needed any other this. My first brood did great without any of that. I had 5 eggs, all 5 hatched and fledged. Only fatality was one that landed on the ground and my mother in law didn't look before letting out my dog. So sad but I have not noticed any wrens around the nest nor do we have cats in the neighborhood. The only other bird that I have seen bother the bluebirds is the Mockingbirds. Could they have taken the egg?

I learned about needing the baffle the hard way. A cat or raccoon got all five of my babies last summer. I was soooo depressed about it. From that point on, I was on Sialis.com reading and learning a LOT.

Anyway, if you read the Sialis site you will learn much more about bluebirding. I have used that site and this Forum for information. Best of luck to you!

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

Okay I will read up on the baffles and conduits. I have never seen any sparrows or wrens near the nest box. The only bird I have seen near it is the mockingbirds. These nest boxes we bought at walmart but they said the were specifically for Eastern Bluebirds so I assume they are the right hole size but I can measure.
Every thing I read and everyone I have talked to about the heat has said that momma bird wouldn't need to incubate much but she has been on them a LOT more than the first brood. Why would that be if it is so hot?
I have never seen or heard of Raccoons in our neighborhood and this happened mid-day so it wouldn't have been that that took the egg.
Today Momma is not on the nest. She and the male are hanging out on the fences near by where they can watch the nest just like yesterday. She did go in last night though.
Should I put up some type of heat shield now? or wait to see if they hatch? Today is day 16. UGH.. I was so excited about them coming back a second time. Now I am just plain worried and feel helpless.
one more question - if I go out and put up the baffles and they birds are dive bombing me (lol). Will that scare them away?

You can even move the nestbox from the fence to a conduit pole (very very carefully with eggs in there) and it wouldn't scare the Blues away. Each pair is different on how they react to someone near their nest. My first year I had a pair that divebombed me like crazy but every year since the pairs that show up haven't divebombed at all. My pair this year stay in the trees about 40 feet away and just chatter at me. Good luck, sure hope those eggs hatch for you! Heat sheilds are good for the texas heat but wait and see if they hatch first, if they do then I would for sure add the heat shields.

Donna