Something else you may want to try is to put a couple of fake eggs in the nest you want them to use. I bought wooden eggs at the flea market, painted them to match the brown hen eggs. They helped quite a bit. My first experiance with moving hens was they laid their eggs on the tool holder. Which meant the eggs fell through the holes. So I put a cardboard box on the shelf part. They liked that idea, and laid in the cardboard box. So when I moved the box, they looked for it. Then I put the box where I wanted them to lay, and shut them in for a week. Bingo!

I don't think you scared them. It is not yet time for them to start nesting, and I'm sure that is just a practice nest. They don't hang around a lot until they start nesting for real. They may add to it and use it come spring, but they may try out other areas as well. I've had them build two or three different nests before deciding which one they prefer.

First off, let me commend you on wanting to help out our native birds. Nuthatches do not often use nest boxes, but an appropriate sized box with a 1 1/8 inch entrance hole is large enough for chickadees and wrens to nest in, but small enough to exclude house sparrows. Also, keep in mind that perches are not only uneccessary, but can do more harm than good as they make it easier for hungry predators to reach into a nestbox and make a snack out of eggs and nestlings. Oh yeah...a few woodpecker species such as flickers and red-bellies will use large nestboxes. If you put one up and fill the entire interior with wood shavings, you'll entice woodpeckers to "excavate" the cavity while preventing house sparrows from claiming it by blocking the cavity.

Unless it's a big nest, or you see more than one nest in the box, I'd suspect plain old House Mouse rather than a Deermouse. Deermice are country mice, Housemice are urban/suburban. Deermice live in groups of up to 10, so where there is one nest, you will often find another. Cold weather means tiny little herds of deermice are trying to move in where it's warm, which is why I have two cats living in the kitchen/back porch. One is a great mouser, the other is a great goof off, but they keep my kitchen rodent free. Otherwise, if I didn't have the cats, I would use glue traps, but only because: (tender hearted soul that I am) 1) This is a farm, so I have plenty of open land to let them go. 2) I know how to get almost any animal off a glue trap without harming it. (other than an insect -sorry, but I've not had much luck saving spiders or crickets) The secret is cooking oil. Corn oil, cheap-o vegetable oil, if you're feeling really bad about making the vermin suffer, you could use extra virgin olive oil, but really, it doesn't matter. Just slide the glue trap and the struggling varmint onto a cookie sheet or sturdy piece of cardboard to support it while you carry it outside. (In our case, that would be outside and at least a 1/4 mile away from the house, but just outside works if you're in town) When you get to the release site, just set the cookie sheet/cardboard down, and pour corn oil over the rodent. Oil disolves the glue in less than a minute, and your greasy little varmint will have pulled itself off the trap and will be staggering away into the grass. The rat/mouse/chipmunk/baby squirrel will take care of cleaning itself, which is why you use edible oil. Lizards, frogs and toads don't clean themselves, but it won't hurt them either. If you catch a bird, you'll have to carefully wash the oil out of it's feathers with dish soap, like they do for seabirds caught in an oil slick. This is also what I'd suggest you do if you catch a litter of kittens. (which happened to one of my neighbors, who called me in a panic about it)