Sounds like your missing the elevator for your bluebird house, just kidding. From what I can tell yes you could have babies in the box by now. I think on my second batch they had built the nest one day and laid an egg the next morning.
You might want to check out this link on the sialis site Bluebird Timetable to be sure though.

As far as getting another bluebird house down the road I'ld try getting one where the roof opens up, I've made several where you can open the sides, but I've never been happy about not being able to get a good camera view of the birds for taking pictures, The only thing about the roof opening up design is you have to have a longer ladder to look into the house, but well worth it. Of course you can use mirrors too.
Keith

suzanne, you could have noticed the nestbuilding in the beginning of July as there is lots of coming and going at that time. Then during egg laying and incubation you don't see as much activity. Nestbuilding can take 1-4+ days, just depends on the female. They lay one egg per day and when the last egg is laid incubation starts. Incubation takes approx 12-14 days or so. So you probably do have babies in the box now, they stay in there generally 16-19 days before they fledge. I would think in your area if you just got them nestbuilding in July they either had a failed first nesting or had to find a new nestbox for their second nesting. Why do you think they rebuilt over their first nest? They will do this though if you don't monitor to clean the old nest out and they start a second nesting.

I think you should look at different nestboxes on the sialis site and see which you prefer. I have both top and front opening boxes around our house, at the park where I monitor nestboxes they are side opening. If you have blowflies in your area side or front opening boxes are better as you can check for the larva whereas in a top opening box it is much harder. I lost two baby blues last year to blowflies when they were in a top opening box, I had to do a nestchange to save the remaining baby. This year we put up five Gilwood nestboxes, they are front opening and supposedly bluebirds love them. Well ours were all taken by swallows, the blues took a nabs style top opening box. Luckily this year we didn't have the blowfly infestation like we did last year. Oh and I have taken and seen some great photos from sideopening boxes too.

Donna

Here is a link that might be useful: nestboxes

Thanks for your answers.

dzyg - I never knew how important keeping track of nesting, laying and fledging Bluebirds was until I found this forum. I always knew they needed help with housing,etc.

So, I am going go by August 1st as having them hatched. I don't know or think they built a nest over an old nest but what I want to know is will the definitely not come back to a box to nest again if there is an existing nest? What did they do in the olden days when we weren't putting up nest boxes and destroying their habitat? Just curious. SO much to learn.

I know I have the wrong type of boxes ( another learning experience) even though they were marketed as such. I feel very queasy about the thought of looking into a box with eggs, or baby birds as I don't want to interrupt them and scare them a way. Since I have the wrong type of box I have no choice but to wait and see.

When the birds have flown the box I will clean it out but I also want to try to move it a little closer to where I can easily view it from my porch. I deliberately put them farther away because everything I read said to do that. Not to bother them, etc. Everyone here says just the opposite.

The great news is that I DO have Bluebirds and they seem to be humming along well so far. The box is active with mom and dad morning and evening when I am around to watch.

I will check into the new boxes.

What area are you in ? I have never heard of blow fly and I can tell you I live in the bug mecca of the entire universe here in SW NH.

...what I want to know is will they definitely not come back to a box to nest again if there is an existing nest?
When birds nest in tree cavities, they will build a new nest over an old one. Eventually the cavity would fill up. But they will always build a new nest, as it's part of the process. For several reasons we think it best to clean out the nestbox after each brood. The most important reason is that as the nestbox fills up, the young are higher up and closer to the entrance hole, where they are more vulnerable to predators (like a cat or raccoon reaching in) or starlings (even if they cannot get their body in, they can grab nestlings as they reach up to be fed, grab them and toss them out). Here is an excerpt from Bet's web site:
"After babies have fledged, clean out old nesting material to encourage another brood. Also, detritus in old nests can attract fire ants, and the nests are sometimes infested with mites or blow fly larvae. I brush out the box, scrape it with a putty knife, and then spray it with a pre-mixed dilute solution of Chlorox (10%), open up the box and let it dry for a day, and then close the door. Do NOT breathe in dust/dried fecal matter (stay upwind, consider wearing a dust mask). Put nests in a baggie, and dispose of them in the trash to avoid attracting predators."
BlueBars

Here is a link that might be useful: http://www.sialis.org/monitoring.htm

nhsuzanne, I am in Central WI. I am attaching a link to some info on blowflies. I think the flies look just like a normal large fly but they lay their eggs in a birds nest and then the larva feed on the baby birds during the nighttime and go down into the nest during the day. They say around 10 larva per baby bird in the nest is ok and won't normally kill the birds but if you get more than that it can. Last year when I did my nest change there had been 3 blues babies and I found over 60 blowfly larva, it was disgusting but since it was a top opening box I never saw any of them until it was too late and we lost two of the babies. The one remaining one was fine after the nestchange and fledged on its own and I got to watch it turn into its adult colors. She was quite the character. This year of three blues nests that I cleaned out one had a few (maybe 5-10) blowfly larva in it, one had absoultely none and one was full of them all the babies fledged fine from all three boxes. These three boxes were all in about a 1/2 - 3/4 mile radius too. You just never know so now I am always leary about top opening boxes. I looked and looked every day in the top opening box by our house that had blues, I hated bothering them every day but I would have hated it worse if they died because I didn't look.

I have some boxes in my yard close to the house (35+ feet away) and some much further away. I take a clipboard with a notebook and have a page for each box that I write notes in when I monitor the houses. It is good to keep notes, that way you can't forget something.

As Bluebars said the Blues will build a new nest over an old one but it is much safer for them to have a clean box each time. I clean mine out the day after or the day of fledging.

There is load of info on the sialis site which is in the link for the blowflies. I have read lots and lots on there. Great info!!

Donna

Here is a link that might be useful: Blowfly info

Bluebars and Donna, thanks for your responses.

I visit sialis.com frequently but new questions about this fun new hobby pop up constantly.

This morning I heard a bluebird singing. Does only the male sing? and if so, does it signify anything important like mating?

I have not seen any fledglings yet but since I can't monitor all the time I may miss them. Plus the rain has been so heavy and the fog and murkiness so thick it's hard to see much at times especially in the evening when I have the opportunity to watch.

Both the male and the female bluebird "sing" but there are many different vocalizations. In the Spring, the male sings loud and clear from a high perch - a MOST beautiful sound - to proclaim his territory and/or attract a mate.
While his mate is in the nestbox incubating eggs, he may sing very quietly and softly from a hidden perch nearby - also beautiful but rarely heard except by his mate. During nestbuilding and incubation, they are rather quiet so as not to attract attention to the nest. (And they don't usually open their beak to sing as some birds do.)
There are danger calls, and calls to locate one another or their young.
There is another high-pitched call we hear mostly in the Fall when they fly overhead; it is thought this call is to keep the flock/family together.
Several years ago in early May, the male of the pair nesting in our backyard disappeared during a freak horrific hailstorm. The female stayed at the top of the highest tree, and she sang, LOUDLY, for the better part of 2 days. I will never forget that sound.
We hear nestlings as they beg for food, of course, and we hear the parents call to them before they deliver food. If you have ever witnessed a fledge, you will likely hear a lot of calling back and forth between the parents and the young as they are coaxed out of the nestbox.
I've also noticed that when I fill the mealworm feeder, the female perches nearby and she makes a little "chip" sound, which I'm sure means "hurry up" LOL.
It would be fun to record some of these sounds, and note the behavior and time of year for reference. But I haven't had much luck with that, thanks to traffic, neighbor noises, wind, dead batteries, time, etc. One early Spring, a male perched on our roof vent pipe to sing. Echoing through the master bath, his singing filled the whole house!
BlueBars

Well I am not sure which one was singing because of the fog and mirk but someone was sitting on a branch nearby singing and it was much more quiet and not as constant as when they were this spring.

All very interesting.

Suzanne, here in New England you can get bluebirds right up till july 30th
that is the cut off date the season ends Aug 1st! The birds will produce eggs
last week of july and be done by labor day with there chicks thats why important
to keep a empty nest box right up till end of July because you can get birds
that late in the season i have seen it many times. Ray