Bluebirds require specific conditions

As I was walking around my garden the other day, I noticed a bright blue object sitting on a branch in one of my pear trees. It was a male bluebird.

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This is not an unusual site around my house because we have a bluebird box for them to nest in. It sits on a post at the corner of my garden and can be seen from our dinner table. For many years we have watched baby bluebirds being fed by their parents. A lot of those years, we have watched bluebirds raise three or four broods.

Besides allowing us to watch the birds raise their young, the bluebirds provide a benefit to my garden by helping keep insects out. I have watched bluebirds enter one of my tomato cages and emerge with an insect.

How do you get bluebirds to start nesting in your backyard?

The first thing you need to know is the feeding and nesting habits of bluebirds.

Bluebirds like open spaces. Because they feed on insects, this gives them a chance to catch flying, crawling or hopping insects. The open space gives them a chance to see the insects and a large area to catch them.

Bluebirds are cavity nesters. They nest in holes in living or dead trees. So if you want to have bluebirds nest in your yard, you have to put up nesting boxes.

Bluebirds will nest in a wide variety of holes, but the holes must be 11/2 inches wide. If the holes are smaller, the birds can't get in, and if the holes are larger, other birds such as starlings or English sparrows will nest in the boxes. The boxes need a sloping roof so water will run off.

Also, there should be a gap between the roof and the side walls for ventilation and light. Research has shown that if you let in a little more light, the bluebirds will continue to nest in the box but other species, such as sparrows, won't.

The Georgia Department of Natural Resources says studies show some bluebirds like a nest with a slot opening across the front instead of a hole. So if you are having trouble getting bluebirds to nest in your box, you might change to a slot opening.

There are other reasons a bluebird might not use the box you put up. One could be the location.

Bluebirds like nests to be on the border of woods and open spaces. If the box is too far from the open area, they might not nest in it.

Also, bluebirds are very territorial. Don't place nesting boxes less than 100 yards from another nesting box.

About 12 years ago, I went to a lady's yard to look at a tree that was having problems. When I got out of the truck, I noticed there were bluebirds everywhere. The lady showed me her bluebird boxes. She had a fence beside her house that had a bluebird box on what seemed like every post. There were about 15 boxes in a row on this fence.

That's not the end of the story. These boxes were two-story nests, and every nest was full. She had 30 pairs of nesting bluebirds. That was the first and last time I saw anything like that. I have placed boxes 20 yards apart and can only get one pair to nest at that distance.

Another factor that can hinder bluebird nesting is how high the boxes are. It is recommended that boxes be 4 to 15 feet from the ground. I have the most success when the boxes are 6 to 7 feet up. The boxes should be cleaned out each year, and the lower the boxes are, the easier they are to clean.

I have heard people say the opening needs to point in this direction or that direction, but research shows it doesn't matter which way the opening faces. But the opening does need to face a shrub or tree. There needs to be a shrub or tree within 20 to 100 feet of the nest. This aids the young birds when they fledge. They are not the best fliers and need a resting spot. This will keep them off the ground and out of the reach of predators, such as cats and dogs.

When you put up a box, you need to mount it on a metal pipe. This will help keep predators out. Snakes, raccoons and other predators can climb up wooden posts. If you are using a wooden post, put a predator guard around it.

I have my bluebird boxes on a wooden post, and a few years ago I looked out and saw the head of a rat snake sticking out of the box. Now I have metal flashing around the post so the snakes can't get into the nest.

If you would like plans for bluebird nests, you can get them from my office or on the Georgia Department of Natural Resources' Web site.

Columbia County Extension Agent Charles Phillips can be reached at (706) 868-3413 or by e-mail at charlesp@uga.edu. The Extension Web site is www.ugaextension.com/columbia.