This was a short project I did with my Dad to show that really all you need to help out the environment is around your house.
Stuff you need:
Chain saw
eleven 2in screws
Drill
(Marker is optional)
(a helper is recommended)

Step 1: What to Look For

Find an old woodpile. (My neighbors cleared a forest so there was no trouble for the there.) You want the wood to be dry and roughly a foot to a foot and a half in diameter.

Step 2: Getting Started

Next cut off a two foot section. (Use a chainsaw it is way easier) Make sure you cut the log perpendicular so it can stand up on its own.

Step 3: Making the Sides

The next step is the tricky one. Cutting off the sides of the log. I eyeballed it and took off about two inches for each side.(there should be 4) Also I didn't number the sides so I had to make an educated guess as to which order that they went. (Number the sides so you won't have to) Be sure that you save the middle piece of wood! Its going to be the floor. Also cut off a square foot piece (or however big your birdhouse will be) to be the roof of the birdhouse.

Step 4: Front Door

For this step you'll need to use the drill to make a small circle, about 2inches wide, in what is to be the front on the birdhouse. I used a knot in the wood so it looks natural. I made mine 6 inches from the top of the birdhouse.

Step 5: Assembly

Now assemble the sides loosely. I used 2 screws for each side. Now cut a 6inch piece of the middle of the log. I put the piece on the bottom of the birdhouse and held it intact by using a screw. Next tighten up the screws that had previously been loose. You want it to look as natural as possible.

Step 6: The Roof

For the roof use the square foot piece. Square it up the put a screw in loosely in the back left or right corner. (so you can open and close the birdhouse for cleaning)