Squirrels will kill adult birds at feeders also. When I lived around them I had squirrel baffles on the poles and all my feeders had grids. My platform feeder had a 1" grid over it also to keep out the starlings and cowbirds that bully the song birds. Keeping the feeders and birdhouses quite far from fences and trees helps also. Squirrels can jump really far. I have a friend who calls them flying rats. I also had a clear dome over one niger feeder. It's a lot of paraphernalia but I felt like I had to protect them if I was going to lure birds to the feeders. Here we have trouble with hawks that sit on the fence and wait for the quail and small birds to get distracted. There's kind of a downside to feeders and bird baths I guess. Birdhouses are easier to protect. Sounds like you have a good plan for the houses. So nice that you are looking out for the babies.

Holcombee: What kind of wren? I'm guessing maybe Carolina? I doubt she would fix it, but I have no real reason to say that. It just seems to me from observation that birds are more fixated on feeding the babies than anything. I don't know how she'd be able to fix the next from the top with the babies in it. I also wonder if she would notice that the bottom of the nest was in need of repair and/or have the sense to do anything about it. Having said all of that it is merely speculation. If the babies do fall out, the parents will still attempt to care for them if they are healthy, but they are likely to become the prey of another bird or cat or night predator. I guess if you do decide to shore up the nest somehow, you should make a solid plan and have a helper ready to hand things to you or run for something you may need. The parents are likely to be somewhat upset, and you want to be able to work as quickly as possible. I have used a deep bucket in which to carefully place the babies (I pick up the whole nest and babies by scooping it up with two hands). I cover the bucket with a towel so that the babies do not become prey or get overheated by the sun. Then I have fashioned nests out of similar materials making sure to try to work the materials into a cup by putting my thumbs into the middle. I just try to get it as close to the old nest in shape and materials as possible. Once I have the new nest in place, I then replace the babies carefully. In the cases that I have done this, they have always been in a nest box, so it is easier to be sure the babies will stay put afterward. The real danger here is if the babies are of an age that they could jump ship and you cause them to fledge prematurely out of fear. Can you tell about how close they are to fledging? Are the eyes open, do they permanent feathers yet? If they are close to fledging, I'd leave nature to her work. This is not an ideal solution, and I'd only use it if absolutely necessary. I think if you are able to add anything under the nest, that would be the best thing. This is one of the reasons that there is such mortality rates in songbirds under one year. Good luck and keep us posted.

We have a house finch nest in our wreath one brood already hatched and fledged, then they were right back at it again. I see a lot of people who don’t notice a disturbance in the nest when the babies go missing. One thing it might be is crows, we had 4 babies and an unhatched egg and a crow came and took all but 2. It tried to come back, but I think we scared it off. We have video of it going to the nest on our doorbell cam. Crows are smart and like to observe, they will watch mama and papa going to the nest and also people checking on it as well. If you are checking on a nest be very aware of your surroundings

I have to say those chicks need better nesting material under them. Clean straw or shredded newspaper would work if you can't buy nesting material at the pet store. You need to keep an eye on the youngest chick since the two older ones are going to get most of the food from the parents due to their size. Hopefully you have on hand some feeding syringes, or even a small spoon, so that you can handfeed the youngest chick as needed. If his crop always looks empty, give him some handfeeding formula or he may end up starving. If you're not comfortable handfeeding, you can move the oldest chick to a warm area for about an hour so that the youngest chicks get a little more food from the parents. So far their coloring and skin look really good, but I worry with the size difference. I stress using nesting material of some sort since you can see in the pics that the chicks aren't able to keep their feet under their bodies and they also look cold. Nesting material helps hold heat and will prevent leg splay.