If you want a bluebird and get a Carolina wren, what can you do? What if you hoped fora chickadee and got a crested flycatcher?You can apply some wildlife management knowledge to put the odds on your side.In the case of squirrels versus the screech owl, the squirrels could take the housefrom the owl if they wanted to. A grey squirrel far outweighs a screech owl. And besides,squirrels sometimes eat nestling birds.Both creatures will use a nest box with a three-inch-diameter hole.To favor a screech owl, have the hole in front. To make it easier for a squirrel toenter, put the hole on the side next to the tree trunk.Mounting a nest box on an isolated tree or a post makes it less appealing to squirrels.They would rather come home by jumping from branch to branch than by running along theground.You can increase the chances of getting your favorite bird by putting up lots of birdhouses. That’s because most cavity-nesting birds are territorial.Once you have a crested flycatcher in residence, it will prevent other crestedflycatchers from moving in nearby. The flycatcher needs to guard a sufficient area to findflying insects for its young.A bluebird has a different feeding strategy. It gets its insects primarily from theground, so it doesn’t compete with the flycatcher.A flycatcher will allow a bluebird to occupy a nearby bird box. A chickadee will allowa tufted titmouse to nest nearby but not another chickadee, and so forth.There are exceptions to the territorial rule. Purple martins and house sparrows, forinstance, remain gregarious during the nesting season.Where you put the next box is important. Some birds prefer a nest box up high in thetree. Others seek a box on a post.The size of the hole can be important. It’s easier to select for small birds than largeones. A large hole admits a wider range of species. A small hole limits the choice to onlysmall birds.A bluebird needs a hole at least one and one-half inches. A tufted titmouse can enter aone-and-a-quarter-inch hole. A chickadee can thrive in a house with aone-and-an-eighth-inch hole.Squirrels may enter a house designed for a small bird. They do this by chewing theirway in. To prevent this, cut the correct-size hole in a tin can lid and nail it over thehole.A birdhouse hole doesn’t have to be round. A triangular hole will do just fine and is alot easier to make. Just cut a 60-degree notch at the top of the board in the front ofyour birdhouse. Put the roof board on, and there’s your hole.Spring is a good time to install nest boxes in your backyard wildlife habitat.For free birdhouses specifications, send a letter to: Jeff Jackson, Forest WildlifeSpecialist, Cooperative Extension Service, 4-404 School of Forest Resources, TheUniversity of Georgia, Athens, GA 30602. “We put up a nest box for squirrels, and a screech owl moved in. How do we run itoff so we can have squirrels?”To me, that seems like a bizarre request. But that’s the question Wes Smith, theUniversity of Georgia Extension Service director in Quitman County, was asked recently.Most wildlife lovers would rather have the owl. Screech owls are far scarcer and muchmore interesting to me than the squirrels.This question is an unusual example of a common problem. If you put up a nest box forbackyard wildlife, how do you get your heart’s desire to move in?