Bluebird nest with just one egg, strange adult behavior

We've had one bluebird couple using our nest box for the past couple of months. They built the nest almost as soon as we put the box up, and since then we've watched their activity daily, but have never seen any babies. Papa comes and sits on our deck and back door handle, and lately, has starting flying to our big kitchen window and and looking in, brushing along it like he's trying to get in. Two nights ago, we watched them keep going to their house and popping in and back out, over and over, so the next morning, we opened the box to take a look. There's just one egg, no babies. How do we know if the egg is good, could they be trying to tell us to get that egg out of there so they can start over? When do you know to remove an old nest? If an egg is not good, how do they rid themselves of it??? Please help, I don't want these cuties to move to another location (with smarter landlords)!!!!

I am no expert on Bluebirds but I am wondering if a predator is stealing the eggs. Seems like this could account for the odd behavior. Have you checked the Sialis sight? It is a wealth of information, here is a link http://sialis.org/ . Wish I could be more help, hopefully someone with more knowledge will come along. Good luck with your Bluebirds.

I'm not sure I can answer your questions, but I will offer some random thoughts and some guesses.

It's hard to say for certain that the egg is good or not without knowing a lot more, including how long it's been in there. I monitor the nestbox at least once a day, starting when she is building the nest. More than once a day if I see suspicious activity. It is important to note the time each egg is laid so you can know how many eggs there are, when incubation begins and accurately predict if and when the eggs will hatch. There could be numerous reasons why she only laid one. But if she is only going to stop at one, she should have started to incubate it. The thing is, if she did try to incubate it, without success, she would eventually give up after about a month. From the time line you describe, any of this is possible.

I think I would check it every day for several more days and if she doesn't lay again, and doesn't seem to be staying on the nest for prolonged periods of time, I'd remove the nest and egg and hope she will build again.

I don't think she is asking you to remove the egg. Even if she is a new female, she could easily build a new nest on top of an old nest or push an old egg down into the nesting material.

The male's interest in your window possibly means he is seeing his own reflection. The males are very territorial during the mating season and often buzz or attack windows, car mirrors or windshields, even water in a mudpuddle.

This message was edited May 20, 2008 2:15 PM

Thanks Dellrose! I didn't think to check the Sialis site, it IS good, isn't it? But who needs it with 2dCousinDave? I love reading your postings Dave, and looking at your photos, you ARE the Master!!! I had told my husband that you advocate looking in the nesting boxes often, and he didn't think that a good idea (not that he knows much about birds really), but I'm going to tell him what you've just suggested, and I'll keep a closer eye on things from now on. The only predators I've seen have been mockingbirds, and they seem more of a nuisance than a predator problem. I do tend to attribute human tendencies to animal behaviors (I LIKE to think my bluebirds are trying to communicate with me!) but I think you're right about the little guy seeing his reflection! Thanks much for your info Dave!!!

I think I'm gonna have to check my bluebird box out too. Until recently, I saw the parents going in and out of the box but yesterday I noticed no activity. I've been expecting the eggs to hatch any day now so was expecting increased activity instead of decreased. I call myself keeping an eye on it, for snakes especially, but there is no one home during the day so anything could have happened. I wasn't sure about checking on the nest either but I think I may get a closer look at it this evening after work.
I'll let ya'll know what i find out

Hi Thea, I agree about Dave and his knowledge of Bluebirds! I have learned more about BB's on his threads than any other single source! We also had similar circumstances with our BB Mama's as far as another female running one off. In my case a seemingly younger one ran off one that had a nest of 6 eggs. I checked the nestbox regularly but never saw the first Mama again! Then the new one started to build a new nest over the one with 6 eggs and I finally had to take the original nest out and put the new one back in. When I took out the original nest there was only 5 eggs and it is still a mystery to me what happened to the 6th egg.

To make a short story long the new Mama layed 5 eggs and hatched out 4 of them. I waited about 3 days and went to remove the 5th egg if it hadn't hatched and when I did all 4 hatchlings were dead. I have no idea what happened to them...the only thing I can figure out is we had a cold snap after having pleasant temps and they just got too cold or something happened to the parents. However...while all this was going on I noticed a pair of BB's checking out another nestbox and they eventually built a nest and as of today there are 4 eggs. I do not know if it is the same pair or not. My nestbox is baffled and I have the Sparrow spooker up so we will see how it goes. I am hopeful that one day we will have baby Bluebirds.

I hope I didn't hijack your thread...I just wanted to share my experience. To me it is a lesson that with birds...you never know what will happen. Best of luck with yours.

Rose and Thea

Did you see the table on Sialis as to problems/clues?

http://sialis.org/predatorid.htm

Hi Mrs Ed. Yes I check the Sialis site quite often and the only thing I can imagine is the cold night we had w/o warning. Another explanation could possibly be farmers spraying their crops. I saw no signs of any type of parasites and I have yet to see a House Wren. That doesn't mean they aren't around though. The nestbox they are in now is the closest to the house and I can see it clearly from my front window..so far so good! Thank you for the link!

Rose, that's not hijacking, it's all good info!!!! I didn't know one nest might be built on top of another, especially when there are eggs in the first nest! And what happened to the sixth egg, isn't that strange!!! Mrs. Ed's informative Sialis link (with an awful lot of scary stuff I also hadn't considered) points out that if something happens to the first female, her successor has some seemingly unkind ways of dealing with her step-eggs. Wow. It all makes me wonder if I have a strong enough stomach for being a bluebird host!

Yep! It's a big job. I honestly don't think I could do it. Certainly not more than one house.

I know it goes on with more than bluebirds though, as I've seen dead babies all over here. A blue jay in the middle of the yard last year. What was up with that? No nests or anything around.

yick

I'm with you Mrs. Ed, don't think I have the stomach for it.

Not to mention, I'm pretty lazy! :D

I might have mentioned before that I had Chickadees nesting in a box, Yesterday I saw a different bird going in and carrying out what looked like shell pieces. I took a look through the binoculars and they appeared to be House Wrens (ugh!!!). Today I went out and just stood near the house and sure enough one came down to read me riot act and their definitely House Wrens.
No more bird houses for me. :-(

Forgot to mention that these are the first House Wrens I've ever seen in my yard.

LOL, certainly no excitement over this new bird.

This message was edited May 21, 2008 2:10 PM

awww, that's too bad. darn it.