Once the birds have been successfully attracted to stay and nest, it becomes the responsibility of those who offered their backyards as temporary nesting places to make sure that the birds are safe in the area. Predators, hazards and threats come in many forms. Potential harm can come from various animals, other birds, insects and even from the structures found around the nesting area. It is important that the nesting birds are given the needed protection and “assistance”, at least up to the time that their young are ready.
Nesting birds, fledglings and birds roosting for the night are very vulnerable to cats. Since bell collars from cats offer the birds only a small amount of protection, it is a good idea to nail a sheet of metal guard or cone to a tree to deter less agile felines. The safest birdhouses are those that are mounted on poles equipped with predator guards. However, the best way to protect the birds from cat predation is by eliminating free-roaming cats by keeping them indoors. The same goes with pet dogs.
A predator guard is a device placed on the pole that keeps cats and other animals such as raccoons and snakes from climbing the pole. It can easily be fashioned at home although there are a lot of choices that are commercially available. An extra guard consisting of a thick piece of wood placed over the entrance provides some protection from the reaching arms of predators. Pole-mounted houses will require an extra flange made of wood or metal attached to the bottom that will accept the pole. The flange and the predator guards should be suitably sized for the poles to be effective. The proper box depth, roof and entrance hole design will help minimize predator access.
Squirrels, raccoons, opossums and snakes can be a serious menace to birdhouses and the birds themselves. An enlarged nest hole can be the work of squirrels that make a meal of the eggs and young once inside the box. Raccoons and opossums will stick their arms inside nest boxes to try to pull out the adult bird, the young and the eggs. Adding a predator guard is usually the solution. Birdhouses can be protected from snakes by putting Vaseline or hot pepper mixture on the metal pole.
Nesting birds can also be threatened by their own kind. House Sparrows and Starlings, two species introduced from Europe are considered pest species as they tend to bully or kill cavity-nesting birds. The nests of these species can be destroyed since they are not protected by law. House Wrens may sometimes interfere with the nesting success of other birds by puncturing their eggs. However, these birds are considered part of the natural system thus no intervention is recommended. Various bird problems may call for several tactics to be effective but the first step is always to identify the bird and what is attracting it. From there, the necessary steps can be taken.
Insects may lay their eggs in birdhouses. Birdhouses should be regularly inspected for signs of gypsy moths, blow flies, wasps, ants, gnats and bees. Gypsy moths can be avoided by refraining from placing boxes in oak trees which they favor. A thin coat of bar soap on the inside of the roof keeps bees and wasps from attaching their nests to the birdhouse. There are some recommended insecticides that can be used especially after the nesting season. Caution should be exercised in the use of lawn-care chemicals that may be harmful to the birds.
One existing problem for birds with regards to modern structures is the use of insulated and reflective glass as they cannot distinguish between the real sky and a reflection of the sky in a window. This failure to know the difference usually results to window collisions. Millions of birds fly full tilt into windows and are seriously injured or killed especially during migration, breeding season and in winter. This can be minimized by breaking up the reflection on the outside of the window with a window screen, flash tape and bird netting. The presence of the birds may require more work but it would be a very small price to pay for the joy of seeing them.