Birds put an incredible amount of effort into constructing nests or excavating nest cavities, but will adding nesting material to birdhouses help encourage birds to take a break and use a convenient house, or will it make the houses less attractive to prospective tenants?
Birds use a wide variety of nesting material, from grasses, mosses, and twigs to animal fur, bits of string, mosses, mud, spider silk, and more. Some birds will even use more unique materials such as strips of plastic bags, snakeskin, or aluminum foil. Despite the variety of materials different birds may use, however, they can be picky about exactly what they choose to construct their nests with and how different materials are interwoven. Adding nesting material to birdhouses is not usually a good idea, and the birds that want to use the house may simply remove any well-meaning additions before they begin nest construction. In the end, this makes more work for the birds and makes a birdhouse with included nesting material less attractive overall.
While most birds are picky and will simply remove or rearrange any added nesting material, birds that do not build elaborate nests may appreciate a thin layer of coarse sawdust or small wood chips added to a birdhouse or bird nesting box. Birds that would naturally chip out a nesting cavity, such as woodpeckers, are not put off by sawdust or wood chips in the birdhouse, and the nesting material can help insulate and cushion any resulting eggs. Owls are also amenable to this nesting material because they are used to reusing old woodpecker nesting cavities. If a birdhouse is specifically meant for owls or woodpeckers, a layer of sawdust or fine wood chips up to one inch thick can be added to the house, but be sure the material is coarse enough that it cannot cause breathing difficulties or a smothering hazard for young hatchlings.
Because most birds do not appreciate nesting material added to birdhouses, birders need to find other ways to attract birds with nesting material without making the actual nesting sites less promising. Options include:
- A small puddle nearby for mud and gravel
- A convenient pile of pine needles, small twigs, and grass clippings
- A mesh suet cage or net filled with cotton fibers, short bits of string, or fur
Many wild bird stores and online retailers offer nesting materials in balls, cages, or other attractive packets that can be hung out for birds to pick from. Hanging or setting these and other nesting materials near promising nesting sites, including birdhouses, can encourage birds to build their nests nearby. Birders can then watch the birds claim nesting material to learn where nests are located for fun viewing, even if the birdhouse isn't a favorite location.
While the soft fluff from a dryer may seem to be perfect to keep young birds warm and safe, it is not recommended as a nesting material. The chemicals in clothing dyes and laundry detergents can be toxic to birds, and the lint itself can crumble and collapse when it gets wet or as growing birds exert stress on the nest. A broken nest offers little protection for birds, and hatchlings can tumble out of a weak nest prematurely, exposing them to injury, cold, and threats from predators.
Regardless of whether or not you have added nesting material to birdhouses, the houses should be cleaned out after every brood of young birds has left the nest and before a new brood is begun if birds reuse the house in the same season. Old nesting material can be contaminated with feces, mites, discarded food, eggshells, insects, mold, and other hazards that can be dangerous for the next set of hatchlings and brooding adults, and it is best to discard all the material carefully. New sawdust or wood chips can be added to woodpecker houses after the house is cleaned. If new eggs have already been laid, however, it is illegal to disrupt or disturb them and it is best to leave the nest intact.
Added to the appropriate bird nest boxes, nesting material can be helpful to cushion eggs and encourage birds to continue raising their families in your yard, but care must always be taken to offer only appropriate nesting material in appropriate ways, and to keep birdhouses cleaned out after each brood to safeguard the next generation.