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Wildlife Houses and Feeders Design Tips

Wildlife Houses and Feeders

Size and Location Matters
Each wildlife species has specific requirements for the dimensions and location of a nest cavity. Some of these requirements overlap among species. Bookstores and the Internet contain a myriad of nesting box plans and designs for most cavity-nesting wildlife species. While the outward appearance may vary widely for these structures, the basic function of a nest box is to attract a backyard resident.

The size of the entrance hole is a major factor in determining what species can use the box and what species can be excluded from the box. This has been well documented in the Eastern bluebird. Now bluebird specialists are promoting a box design with a long, narrow slit at top rather than a round opening. These are preferred by bluebirds, but are unattractive to house sparrows.

The size of the internal cavity is arguably more important than the entrance hole diameter. Be aware of typical nest cavity dimension and placement characteristics for your target species. If you purchase or build a nest box, make sure the dimensions and entrance hole are the right size for the species you wish to attract. Recommendations for some common Indiana backyard wildlife species are listed HERE.

Once basic cavity dimensions are met, you need to choose a location based on the requirements of your target species. Review recommended locations in the table above and the resources at the end of the publication. Ask yourself these questions

• Is it at the height the animal feels comfortable?
• Is the cavity protected from predators?
• Does the nest structure get the proper amount of sun or shade to provide comfortable temperatures?
• Is the nest structure near required food, water, and escape cover?

Choosing and placing nest structures that favorably meet these criteria will increase their use. Arrangement can also be important. Purple martins need their boxes clustered into groups. Apartment houses or groups of gourd nests work well for purple martins.

Basic Design Tips
Follow these basic design tips, maintenance suggestions, and predator reduction advice to make your nest structures more useful to your backyard visitors.

Use quality materials that are weather resistant. Exterior grade plywood and lumber are good choices. Cedar and other rot-resistant woods are best. Avoid using treated lumber and metal.

• Avoid painting or staining inside nest boxes. Painting the outside can prolong its life and may be attractive for some species (white for purple martins, for example).
• The roof should be sloped to allow water runoff and should hang over the sides.
• Drill at least four 3/8-inch drainage holes on the floor.
• The roof or one side should open to allow easy access for cleaning.
• Avoid perches. Natural cavities don’t have them and neither should your nest box. Perches also allow European starlings and English house sparrows, non-native invasive species, to harass native cavity-nesters and take over a nest box.
• Near the top of each side, leave gaps or drill 5/8 inch holes (at least 2 per side)
• Erect your nest box well before the average start of the nesting season. Some species will set up their nesting territory 3 to 4 weeks prior to egg laying.

Maintenance
After the nesting season, clean out the old nesting materials. While there are some species that like to build a new nest on top of old nests, most experts agree that cleaning out boxes is the best practice. This will minimize parasite infestations and will make the box less attractive for deer mice which can exclude birds the following spring. If unexpected residents occupy a nest box, you may need to erect additional houses. Nest boxes for year round residents, such as screech owls, gray squirrel, and fox squirrel may be used throughout the winter.

Problem Species
Monitor your nest boxes for use by house sparrows and European starlings. Competition by these species has been a leading factor in the decline of eastern bluebirds. Proper entrance hole diameter will exclude starlings (1.5 inches or less) and house sparrows (1.25 inches or less) from nest boxes. If you find a starling or house sparrow in your nest box, remove the nest and all of its contents so the house is available for your target species. However, this is just a temporary solution since they will simply rebuild their nest, although persistence may produce results. House sparrows have abandoned a site after repeated (3-4 times) destruction of their nests. You may also close the box entrance until the expected arrival time of your target species, although this would not work for year-round residents. Trapping and humanely dispatching starlings and house sparrows is another method of reducing nest box competition.

WARNING! House sparrows and European starlings are exotic species to North America. They are not protected by law and can be legally trapped or killed using safe and approved methods. Most other species are protected by federal and state laws so be sure you properly identify your visitor before taking action. Boxes for some species may be utilized by native species other than your target species. For more information on laws and regulations protecting Indiana wildlife, see Animal Damage Management – Rules and Regulations in Indiana listed in the reference section.

Predation by raccoons and house cats are serious problems in most areas of Indiana. Many nest box designs have predator guards that prevent nest predators from enlarging the entrance hole or from reaching into the box. For additional protection, install structures that prevent predators from climbing to the nest box. Generally, nest boxes on trees are easier targets than those mounted on poles. Using a cone or metal band can inhibit cats and raccoons from ascending trees or poles. When mounting inverted cones or other predator guards locate them high enough on the pole or tree so predators can’t jump over them.

When placing a predator guard on a tree or pole, look around. If a predator can gain access to the nest box from adjacent trees or buildings, you will have to prevent access to all of them or select an appropriate location that is easier to prevent predator access.