Could there be a shortage of food (bugs) - due to lack of rain - that made the babies starve? I did note that a couple of times I saw the mom and pop bluebirds eating suet and sunflower hearts. Seemed odd since I only have seen them do that in wintertime.

What bothers me is the missing babies. I believe they are to big for wrens to remove. I would love to see some pics of the babies and your set up. Baffle, sparrow spooker etc.??? I'm pretty sure you've been on the bluebird forum and know the deal with all that. My blues eat suet all year and even feed it to the babies.
Cathy

My first guess would be a snake entered the birdhouse, ate a couple of babies and stayed there digesting them. It was probably not a large snake because a couple of the babies were enough for it. The parents were unable to feed the remaining babies because the snake was in the birdhouse. I've seen a similar thing happen before, almost full grown babies dead in the birdhouse and a piece of snake skin as evidence of what happened.

BBCathy, I also think that house wrens are not to blame, although there are some around my house. We have no HOSPS here. Here is a pic of the little angels... my setup is a typical square box house with a baffle, box is mounted at about 5 feet to the opening, no spooker. The baffle is not a stovepipe type, though... the top is open. Its a piece of 4" PVC pipe. I have been on the BB forum especially when I first put up a house 5 years ago. I can't believe it could be a snake, although I know it is possible. I know my yard very well, as I am a gardener, but we have stone walls and I suppose a snake could have come out at night. It just seems unlikley to me, but that may explain things. The mom and pa bluebird have been seen a couple of times, but they are not re-nesting here. So sad. I had one nesting of chickadees this spring from that very box. I guess I need to buy the stovepipe baffle. And now I know how important it is.

Here is a link that might be useful: {{!gwi}}

Well I may have to agree with snake although 4" is not really coon or snake proof (should ideally be 8" stove pipe for coons) and it is not snake proof even if it were 8" b/c of the open top. Was it more than 10 feet away from a fence or tree? Squirrels or cats can jump to the box. Most predators would eat them all though and the nest would appear disturbed. The nest looks undisturbed though which suggests snake and if the Mom and Dad were around they certainly had the daylights scared out of them so they would not return to take care of the other two. If it were a coon they probably would have returned for the other two unless they were interrupted. Snake too for that matter. At that age Mom would not have been brooding and Dad would have been able to take care of them alone even if she were killed. All in all I'd have to think snake but we may never ever know the real story. Vist www.sialis.org and see if you can figure it out.
Let us know what you think. Condolences,
Cathy

Cathy, After reading your comments, if I had to choose between a coon and a snake whodunit, I would have to say it could more likely be a snake because if a raccoon tried to climb the pole, it would likely be off kilter... you know, not exactly straight up, anymore. Its a screw-down type of pole assembly which is in the ground pretty good, but its not sitting in concrete. The box is in the middle of my yard with at least 50 feet of grass in all directions. Its still so weird because I have never seen a snake here. I have read the Sialis site time and time again and ... the sings of squirrel predation do not fit my situation, but I do have some of those around... chipmunks, too. I will likely never know what happened. Thank you for your 2 cents. ;(

So sorry to hear about your little Blues. It could be a snake, but from what I understand, they are not a big problem up here in the colder zones.

My Bluebirds had a tough year too, and I know exactly how you feel. Their 2nd brood was raided by a raccoon, so I baffled the snag with sheet metal, and they tried again. The eggs for the 3rd brood were ejected by House wrens just a week ago. The Bluebird pair hasn't been seen since. :(

Sorry for yours as well Terrene Do you have any boxes up? I know they've been in that snag for a couple of years. Now that they've been unsuccessful there they may choose a box where you would have them better protected.
Cathy

Hi bbcathy, yes there have been boxes up both years the Blues nested here. They had never shown any interest in the boxes and preferred to nest in snags. My lot is savannah habitat, and shrubby in the back so it attracts House wrens. There is no surefire way to protect a nest box from House wrens anyway.

Next year I don't know what to do. I will definitely try to do more clearing, and discourage the wrens, however, in case another Bluebird pair shows interest here.