House (English) Sparrows photo by Deanne Fortnam
I am a long time bird advocate. I have been building birdhouses or nest boxes, as we call them, for over 25 years now. There have been many different styles, sizes and materials used for building nest boxes over the years but it all comes down to what is best for the bird using that particular nest box. This of course depends on the species of bird and that species’ behavior. The materials you use for building the nest box may also depend on what you can afford or what you have available. The main thing you must always keep in mind is what is best for the bird.
For most of my birdhouse building career, I have used cedar or redwood boards. These are very durable products when put together properly with exterior grade screws instead of nails. I have nest boxes that are 26 years old and only need an occasional repair to the entrance. The repair problem is usually caused by a predator or another species of bird attempting to enlarge the entrance to the birdhouse to gain access for themselves.
This is the first year I will be testing nest boxes made from materials other than wood. I have made a couple of birdhouses out of PVC pipe this year to see how my Western Bluebirds and Oak Titmouse residents like them. These nest boxes are made with PVC pipe, with a wooden floor and roof. If you have House Sparrows in your area, you might try the PVC boxes as the sparrows seem reluctant to use them. I know some folks who have had good results with them so I will give it a shot.
I have also been introduced to a nest box made from TREX, the artificial decking material and aluminum diamond plate. I don’t know if I will try this design or not. If I am able to use scrap pieces of TREX, I may test these boxes. They may be useful in public places like parks because of their durability.
Now let’s talk about the most important aspect of building nest boxes and birdhouses, monitoring. It is critical that nest boxes be monitored. If you have one birdhouse or you have several hundred nest boxes, they must be monitored to make sure the occupants have a safe place to breed and raise their young. We want to be providing a home for bluebirds and other beneficial birds not setting up a breeding ground for House Sparrows and European Starlings.
European Starling photo by Deanne Fortnam
House Sparrows are probably the most important cause of Bluebird decline other than loss of natural nesting cavities. House Sparrows not only destroy songbird eggs, they kill the adult and the young birds by attacking them in the nest box and scalping the birds with their hooked beaks. Then to add further insult, they often build their nest over the bodies of their victims.
If you can’t find a safe place away from House Sparrows for your nest boxes or undertake a sparrow control program, you are probably causing more harm than good. You can run a year round House Sparrow trapping program to help your resident song bird population. There are traps available for this purpose and specific nest box designs to help rid your area of House Sparrows.
Since House Sparrows don’t migrate, you may be able to keep them away by trapping and destroying the House Sparrows in your area. The birds you trap can be given to local bird rehabilitation centers to feed to injured raptors. House Sparrow nests must be removed and destroyed immediately when found. You must also destroy the eggs and young. Never let a House Sparrow fledge from one of your nest boxes.
This may sound radical to some but House Sparrows and European Starlings are the only bird species affecting bluebirds not protected by law. The European Starling is a very aggressive bird that will drive away all your other cavity nesting birds. The easiest way to rid yourself of Starlings is to make your birdhouses to precise specifications. Make your bluebird nest box entrance holes no larger than 1 9/16” and keep them that size with good portal protectors.
For more information on these non-native, nuisance species, go here: North American Bluebird Society