Placing free birdhouse plans pdf or roosting boxes may also be used to help maintain populations of particular species in an area. Nest boxes should be made from untreated wood with an overhanging, sloped roof, a recessed floor, drainage and ventilation holes, a way to access the interior for monitoring and cleaning, and have no outside perches which could assist predators.
Boxes may either have an entrance hole or be open-fronted. Some nest boxes can be highly decorated and complex, sometimes mimicking human houses or other structures. Constructing birdhouses can often require a plethora of tools, for more concise craftsmanship. The diameter of the opening in a nest-box has a very strong influence on the species of birds that will use the box. Many small birds select boxes with a hole only just large enough for an adult bird to pass through.
This may be an adaptation to prevent other birds from raiding it. In European countries, an opening of 2. The size of the nest box also affects the bird species likely to use the box. Seasonally removing old nest material and parasites is important if they are to be successfully re-used. The material used in the construction may also be significant. Birds nesting in woodcrete sites had earlier clutches, a shorter incubation period, and more reproductive success, perhaps because the synthetic nests were warmer than their wooden counterparts.