This is a simple open fronted bird nesting box for small to medium sized birds such as song thrushes, (European) robins, wrens and flycatchers. I was going to publish an Instructable to make a box for hole-nesting birds, but Cheapchuck has done such a good job HERE, I'm going to make a few of his.
Some birds which were once common are declining with the loss of habitat and changes in climate, and gardens are a valuable refuge. Wild birds are very entertaining to watch and any effort to attract them to the garden and help them to breed is well worthwhile.
You also have the added benefits of free pest control. Birds, especially during the breeding season, will hunt down and eat many garden pests. It has to be better to encourage a natural balance of wildlife in your garden than to upset the eco-system by spraying with pesticides.
Step 1: Tools and Materials
I used a piece of rough pressure treated timber which had been at the back of my shed for many years. If you are buying new, use plain timber. It won't last as long as treated timber, but recently treated wood can harm the birds you're trying to help. Building the box took me a bit over an hour and that included designing it, so with a bit of effort, you could make a few in an afternoon.
Step 2: Measuring and Cutting
If you're using different width or thickness timber you will need to adjust the measurements. If you cut the side pieces first it's pretty easy to work out what you need to change by holding the sides against the back-piece and measuring the required lid-width and length. The lid length will be the width plus twice the thickness. The length of the base will be the width minus twice the thickness.
I've given measurements in Imperial and metric units, although nothing needs to be exact as anything you make is going to give the bird a palatial home much more secure than some of the places you find them nesting.
Step 3: Putting It Together
First, attach one of the sides to the back-piece, and then fit the base. Turn the box over as you're doing this, so you're always hammering into the piece against the workbench. Then put on the front of the box, not forgetting the bead of glue on the edges.
Now more glue, and carefully line up the other side and press down. The protruding nails will keep it aligned. Hammer the pins home. You'll need to put a few more panel pins through the front and back-piece into the base.
Step 4: Finishing
Work a bead of glue into the crack where the lid meets the back-plate to keep rain out. Also rub some glue into the end-grain at the top, sides and bottom with your finger to stop water being absorbed so easily.
Drill a couple of holes, top and bottom of the back-plate so you can attach the box to a tree branch. If you don't have a drill, cut two pairs of notches at the sides level with where the holes would be
There are wildlife-safe wood preservatives available and you can treat the outside with one of these if you wish, but never use normal preservatives such as creosote. Never treat the inside.
It would be safe to paint the outside, but I much prefer the natural look and even new wood will quickly weather,
Step 5: Location, Location, Location.
Where you put the box will determine how successful it is.
Different birds have different preferences, but in general it should be :-
At least 8 foot off the ground to keep safe from predators.
Not too near a food source, or other place where birds gather.
Semi-shaded, and definitely not in full sunlight.
Partially hidden by foliage, but with a clear flight-path to it.
If you live in town and don't have a suitable tree, put a box under the overhang of the house. Town birds need even more help as they have a very limited natural habitat.
For more information on birds and bird-watching, check out the RSPB website or the American Birding Association.
For an introduction to maintaining your garden and encouraging wildlife without using pesticides and weedkillers, look at this section of the BBC website or this site if you're in the US.
*** UPDATE ***
We've now got a family of wrens living in the box, which makes it all worthwhile.