The American Kestrel is North America's smallest falcon, and unlike its larger cousins, this beautiful little bird chooses to nest in cavities (i.e., holes in trees or other objects, such as utility poles and buildings). They will also accept artificial nest boxes placed in suitable habitat, which is open areas such as pastures and hay fields. This Instructable will hopefully help you construct your own safe and secure nest box that will also be easy to clean and maintain. The design is based on plans refined by Dr. John Smallwood and Richard Melvin for use in the difficult environment of Florida, and should be suitable for use everywhere.
This box is also suitable as is for screech owls, and could be scaled appropriately for a variety of other species (wood duck, bluebird, swallows, etc.).
Step 1: Box Plans
Here are the dimensions of the cuts that you will need to make - feel free to reorder them in order to accommodate the quality of your lumber. You'd be wise to make sure important parts, such as the back, front, and top, are cut from board sections lacking cracks or knots.
This Instructable follows the order of steps that I used to construct my boxes, but you are free to mix things up in any way you choose. What seems like a logical and efficient workflow to me might not suit you well, and there are many ways to end up with a functioning nest box.