When spring rolls around, the air is filled with the sounds of birds singing, chattering and chirping as they return from warmer climates to their northern homes. To help them find places to nest, humans often put out birdhouses, sometimes attaching them to trees to serve as homes for the birds. Although birdhouses fastened to trees will be very solid, they can be an open invitation to such predators and marauders as squirrels and cats unless added protection is provided. If done right, the birds will be safe and the birdhouse will not harm the tree.
Prepare two or three nails for use in attaching the birdhouse by placing a washer over each nail, then slipping a spring over the nail. How many you need depends on the size of the birdhouse.
Check the birdhouse for usable nail holes. If there aren't any, drill two or three starter holes across the top of the backboard. Make sure not to poke through the roof or it will leak.
Hammer in one of the prepared nails through a backboard hole in the birdhouse. Hold the birdhouse firmly against the tree at your chosen height as you do so. The washer and the spring will be in front of the board, not between the tree and the birdhouse. Stop hammering when the spring begins to compress just slightly. This will allow the tree to grow and push the birdhouse outward without damaging either the tree or the birdhouse.
Repeat the above step with all of the nails. It might help to have them angled slightly upward to help keep the birdhouse in place, but if the tension is adequate on the springs it will be solid.
Attach the squirrel guard to the tree below the birdhouse. Follow the instructions with the guard. Be sure it wraps completely around the trunk. Make sure the guard is wide enough to prevent a squirrel or a cat from getting past it and reaching the birdhouse.
Cover the squirrel guard with a layer of petroleum jelly and cayenne pepper. This will cause the surface of the guard to be both slippery and unappealing to predators.
When attaching a birdhouse to the trunk of a tree, select a sturdy tree that can easily hold the weight of the birdhouse. Do not attach more than one birdhouse per tree. Birds choose birdhouses based on a variety of factors, such as the size of the entrance hole, height at which the birdhouse is hung, the overall size of the birdhouse and the general habitat in the area, including vegetation and available food. Research what the birds you would like to attract prefer and place your birdhouse accordingly.
Birdhouses can be very vulnerable to attack by predators. Make sure you have taken all possible measures to protect the birds, as the chicks will be very vulnerable for a long period of time. Do not place the birdhouse in an area of strong summer sun, or the chicks inside it will die. Choose a tree for your birdhouse that is not near other trees or overhangs that could allow predators to cross over and approach the birdhouse from above.