Since you have been following this forum I am assuming you have your nestboxes mounted properly on a slick metal pole with a predator baffle and at least 15 feet away from trees/fences etc. Did you have a sparrow spooker? My initial thought would be House wren....they will poke holes in eggs and throw them from the nestbox. How close to trees or bushes are your boxes. If House wrens are in your area boxes placed at least 50 feet from brushy areas work best. It could also have been a House Sparrow but for the most part they would just smash the eggs. Hopefully your box is baffled with a proper baffle (not the cone shaped ones) because if a raccoon could climb up the pole it would eat the incubating female too. Only mentioning this because you said you haven't seen her. I sure hope that wasn't what happened! Is the nest messed up at all or does it look the same just without the eggs?

Hopefully it was just a wren and your female is ok! Are the other nestboxes that you have empty yet? No other birds nesting in them? It is very likely that this pair will renest in one of your other boxes if the female is ok. Hopefully you wont have the same problem. Wren guards as seen on sialis.org do work so if you suspect them and they haven't found the box yet, you could try one if they do renest.

Good luck!
Donna

Thank you Donna, I truly enjoy your feedback, it is obvious you know what you are doing.
Unfortunatly, there are some things I could have done better, like the baffle and the sparrow spooker, wren guard. My placement is adequate I think, one small tree but no bushes or large trees. And I had not seen any aggressive birds trying to enter the nestbox. The female bluebird had been incubating every time I looked, with the male standing guard closeby, so I thought everything seemed ok. And I only had a few days to go....
The nest is still intact, one egg remaining (why did they leave one?), I searched everywhere and could not find a morsel of a shell lying around. The other boxes have chickadee nests, I believe, being built (should I discard them?) I have a total of 4 boxes, one looks like it may be the start of a bluebird nest, the other 2 look like a mossy nest, no eggs.
Once again thank you. Also, what is the best type of sparrow spooker? And are Wren guards handmade?
Trying again!
Rosanne

Oooh, mossy nest = chickadees!

I had a similar experience: Mama laid 3 eggs, and two days later, only 2 were left. Absolutely no sign of struggle, no egg laying around anywhere - it just vanished! No way anything except another bird could have gotten into the nest. So....very strange. And disappointing, because after that Mama abandoned the nest (even though she still hangs around from time to time).

Sounds like your placement is good...but you do need to add a baffle. Normally when eggs simply disappear it is due to wrens. They throw them from the box and other predators like crows pick them up off the ground which is why you cannot find anything left. Have you seen your female again yet? As far as the Dees nest (which are mossy nests) please leave it, they are awesome little birds and I just love them. They are also low bird on the totem pole so often have failed nestings and they only nest once per season. They need all the help they can get. I would recommend adding a 1 1/8 inch hole reducer onto their box once they start laying eggs. It can be hard to tell when they start because until they start incubating (and sometimes after) they cover their eggs with a hairy blanket.

Hopefully that one that looks like a bluebird nest is your pair starting a new nest. I will attach some pics of my sparrow spookers (put up only after the first egg is laid and taken down after fledging.) and my wren guard (put up again after first egg is laid and taken down after the eggs have hatched and the nestlings are at least 7 days old).

Homemade spooker...need to have the mylar come out over the top of the nestbox..most spookers have two dowel in a vshaped coming out over the box....

wren gaurd..this one does not have sides..only shows the front..

this one was on a Dees nest...I slowly added sides to it for stability and to prevent wrens from landing on top and looking over and being able to see the hole...I added the sides in stages though which is why there is so much duct tape....wren guards are normally accepted easier if you do it in stages..

I typically make the wren guard come out further than sialis recommends...I think I have four inches from the nestbox to the edge of it. But then what I do is look from every angle that a wren may be at and make sure that once i am done adding the sides that the hole is not visable from all these sides. One year I had a long side on one side of the box, as long as the front was but the other side had only a short one inch side for stability and nothing else as that side faced our driveway and had no place a wren would be.

Good luck, hope you can get a successful nesting!

Donna

Just wanted to add to make sure you add a raccoon baffle. You can either make one or buy one at your local bird store such as Wild Birds Unlimited. Also, you can buy a sparrow spooker already made if you aren't handy (like me). Go to www.sparrowtraps.net and click on "spookers." Be sure and check out www.sialis.org for all kinds of good information.

Good luck!
Carol

Thank you so much for all the information. Everyone is so helpful! Donna, the pictures were incredible and helped me understand. Still have the male flying around, no female, hopefully soon there will be nest building again!

Glad it all helped! I just want to add being that you are still not seeing a female and you didn't have a baffle, it really could of been a raccoon. Not positive of course since somethibg could have happened to her out of the box too but hopefully you have added a baffle and hopefully your male will find another female.

Good luck!

Donna
Donna

If the female was killed, the male will likely stay in the same territory and start singing to attract a new mate.

One word of caution on the Wren Guard. You want to make it waterproof ,rain on cardboard can turn it into mush where it will hang over the hole & Mom cant get in. I duct tape my cardboard so it cant get wet ,I also put supports (like a stick) to be sure it does not collapse & block the entrance.

great advice, thanks!

another question, should I remove the intact nest from the box and do I relocate the box? Will they build and select in the same area?

I'm rather new to bluebirding, but I suspect people will tell you to move the box if you can. However, it's 50/50 that a wren (same or different) will discover the new box, so it's kind of a gamble whether it's worth the effort to move it.

Yes, remove the intact nest. Check it for blowflies by gently tapping it, and if there are none, put it in a paper bag and staple it shut. You should keep it in case something ever happens to a future nest and you need to replace it. Mama will be a lot happier with a real nest rather than a makeshift one fashioned by you. :)

Oops - forgot to say that it's 50/50 whether they'll rebuild in the same area. Sometimes if a nesting fails they'll move onto a different site. My pair, on the other hand, seem to be quite attached to the box and I suspect they're going to try a second time in the same box. However, even if they move on, they may come back to your site next year.

Yes remove the nest (save it in a ziplock bag in case you ever need to do a nestchange). You can move the box or you can simply make it face a new direction. My sister had a HOSP attack her blue eggs once. She removed the eggs/nest, turned the box and the blues came back and rebuilt and had a successful nesting.

As for the wren guard. I use the heavy cardboard that computer paper boxes are made out of, it has never turned to mush in even heavy rains and lots of rain. Sides make it much more stable and prevent the front from blowing in and out wint the wind. I also screw the piece of carboard that is taped to the roof of the box to the roof of the box because sometimes with duct tape, when it gets wet in will loosen up some. I do use water proof duct tape now but I like the screw in the top for added stability. Good luck!

Donna

Is a nest change exchanging a new nest for an old one that you'd saved? Why would you ever need to do a nest change?

If for some reason a nest gets really wet or if it is full of blowfly larva a nestchange is a good thing. I did it once due to blowfly, found two dead babies on a nest check, cleaned out the old nest which was full of midsized blowfly larva and the remaining nestling went on to fledge, it would have died for sure that next night if I hadn't done the change.

Donna

Ditto to what Donna said.

Thanks Donna.

I saw the female bluebird this morning checking out 2 of the boxes, one box was the one that the wrens attacked , so scared........I had removed the old nest, perhaps I shouldn't have? Will she rebuild?

dsu4neiman....you did the right thing removing the old nest. She would build a new one over the old one anyway and you wouldn't want that. They always build a new nest on a new nesting. Good luck!!

Donna

Mine have been "checking out" the original box for three days since I removed the nest. She will rebuild if she re-chooses the site.