Donna, are you worried about the wrens showing interest in this nestbox again? That's a ligit concern! I'm not sure what to tell you. Maybe Blue Belle will check in here and give you her suggestions.
Tammy

Donna, I'm not exactly sure about the sequence of events in your boxes, so I'll have to ask some questions. Have the dees finished in the "dee" box? Which box is better sited for blues? (Really no matter the answer to that question since they don't always choose the better located ones.) Are both of these boxes suitable for blues but one had a reducer?

The thing is, since the HOWR have been in both boxes the very best thing to do is relocate both if possible and face them in a new direction. A 90 degree turn should do the trick. Doing that might hide the holes from the HOWR for a long enough time. The current thinking is to install guards on the day of the first egg. BUT, that might be too late in this case. I think it's hard for them to accept a guard during nest building because it is harder to get under a guard with nest material and without eggs they are not as attached to a box. This might be what you will have to do, but you will have to make that call. If you do install a guard during construction, I would advise a modified guard that is without sides and shorter than what I normally use to make it easier for the female. A female who is inexperienced with guards would have a tougher time than one who is. If she accepts the small guard, then when she lays the first egg you can graduate her to a guard that covers the entire front of the box and part of the sides. That design is very effective in deterring wrens and is the kind I used successfully on my blue and TUTI boxes this year.

I hope this is some help. Cathy has tons of experience with HOWR and is having success against hers. When she checks in, she will likely have more advice.

Thanks Tammy and Blue Belle, I guess I didn't really explain things real well. I call it a chickadee house as it was supposed to be for the dees, it had a 1 1/4 hole but the woodpeckers enlarged it to 1 1/2 this winter. Chickadees had built a nest in it but were being harassed by HOSP so we put a reducer on it of 1 1/8 but the Dees were already run off before we got it on. A wren removed the chickadee nest and was adding sticks that I took out every other day. The Blues were showing interest in the box so I removed the reducer just to keep them in the yard and hoping they would find the one remaining empty bluebird box in the yard. Which they did find and I had thought they chose. Totally forgot to put the reducer back on the chickadee box and then realized the Blues changed their mind and chose the chickadee box. They have started a nest too. A wren was fighting with them for the box but is now gone, hopefully for good. I guess my question is no longer a question anymore since the Blues have started a nest now. I will try turning the box though like you suggested. This box is closer to the trees than the Bluebird box is though so the wrens could find it even with turning the hole.

Thanks for your advice!

Donna

Donna Blue Bell gives good advice. We've been having troubles with the HOWRs for sure. Is it possible to move this box more out and away from wren habitat? I've moved them short distances at a time with no problems. Maybe another box would help to keep the wren busy until the blues get the nest finished with an egg and then add the guard. Keep us posted.
Cathy