This nest box was designed specifically for chickadees: note the small entrance.

MORE AND MORE PEOPLE ARE LOOKING AT BIRDHOUSES as more than garden accessories. They’re becoming a key part of backyard bird operations. And more savvy retailers are devoting valuable floor space to bird-related housing to better serve both their customers and birds.

Birdhouses, a.k.a. nest boxes, have become much more specialized and function-oriented than the little structures we hammered together when we were kids. There now are houses specifically designed for bluebirds, purple martins and chickadees, as well as other species. They range from the whimsical and lovely to the straightforwardly functional. Some are ceramic, others come coated with birdseed. Some even have roofs fashioned from license plates.

Not all bird species nest in houses – only about 10 percent of backyard birds do and these have some pretty particular requirements (see sidebar). Retailers can perform a real service to customers by stocking birdhouses that are built to last, designed for a particular species and able to stand up to weather extremes.

Avoid houses that are cheaply constructed, with sharp edges or protruding nails. These can harm birds.