Always hang birdhouses in a tree-friendly way.
If you perused a list of the world’s endangered animals, you’d find that habitat destruction is one of (if not the) most important causes leading to their collective plight. While you can’t do much to protect the Amazon Rainforest or the Great Barrier Reef all by yourself, you can make a little dent in the worldwide habitat problem, and it isn’t really hard to do, either.
Let’s talk about birds. Many birds, including beloved species like eastern bluebirds and white-breasted nuthatches, are cavity nesters. Throughout the history of these species, tree hollows and abandoned woodpecker nests were plentiful, and they easily found suitable nesting locations. However, many forests have vanished, and the bluebirds and nuthatches of the world are struggling to find suitable nesting sites.
Here’s where you come in: You can mount bird houses on the trees in your yard to help give the birds a helping hand.
Pick Your Bird; Pick Your Tree
Start by selecting a good target species (or handful of species) that lives in your area and nests in cavities. Then, consult a chart like this one to determine the proper size house for your target species. Each species tends to prefer houses placed at different heights or in different orientations, so be sure to research this as well.
Now, equipped with an appropriately sized bird house and an understanding of what the birds are looking for, you can set out to decide upon the best tree. Select a tree with a 4- to 12-inch d.b.h. (diameter at breast height), and plenty of low branches that will allow the birds to perch near the house. Avoid placing bird houses on trees with completely bare trunks or, at the opposite end of the spectrum, trees with an impenetrable thicket of low branches.
You can choose almost any tree species you like to support the bird house, but pines and other sap-spewing species will lead to sticky fingers, so hardwoods are your best bet. Some species tend to look for nesting spaces in specific species; house sparrows for example, like to nest in elms. Trees that produce a quality food for the birds, such as cherries, hollies and oaks, are among the best possible choices.
Fasteners and Fabric
Now that you have your bird house in hand and a tree in your sights, it is time to attach the two together. Most people accomplish this task with things like nails or screws. This will surely keep the bird house firmly attached to the tree, but it is also likely to harm the tree in the process.
When you drive a nail or screw through the bark of a tree, you expose the delicate phloem, cambium and xylem to fungi, bacteria, viruses and bugs. While your tree may be able to compartmentalize the wound and fight off invaders, it is an unnecessary risk to take. Accordingly, you should avoid hanging your bird house with nails or screws.
The best way to hang a bird feeder without harming the tree is through the use of straps. Flat nylon webbing (like this) is a great option, but you can improvise and use just about any kind of cordage or strong fabric if need be. You can glue or sew Velcro to the webbing, which will let you strap the birdhouse directly to the tree without having to use any invasive fasteners. Alternatively, you can purchase nylon webbing straps that have buckles or other fasteners already attached.
Mount and Monitor
Place the birdhouse on the tree and tighten the straps until the house is sturdy enough for use. The issue of strap tightness is not a well-defined science: You must be sure that the home will not drop to the ground with a tiny avian family inside, but you should avoid attaching it to the trunk any tighter than is necessary to reduce the chances of injuring the tree.
But mounting the birdhouse is not the end of the job – you must monitor it and periodically loosen the straps to account for the tree’s growth. If you leave the straps too tight for too long, you’ll girdle the tree, which is likely to result in its eventual death. A good rule of thumb is to remove and re-mount the bird house every year. You can even use this time to clean out the bird house, leaving it fresh for next season’s inhabitants.
While bird houses are a great way to give Mother Nature a helping hand, bird houses aren’t the only way to make a positive impact in the lives of your local birds. Simply maintaining a vibrant colony of trees gives the sparrows, titmice and cardinals in your neighborhood some of the resources they need. But to do this, you have to keep your trees healthy.