Even Bluebirds Get the Blues

Image Gallery This lovely little insect-eater can't make a comeback without some human help. SAMUEL L. SKEEN

A scant 50 years ago, the eastern bluebird (Sialia sialis) was common throughout the rural portion of eastern North America. However, as a result of such factors as habitat loss (particularly the loss of nesting sites), the competition of imported species (including the English sparrow and the starling), and pesticide poisoning, this valuable and beautiful member of the thrush family is now so rare that many country folks can't remember when they last saw one. Incidentally, the western bluebird (Sialia mexicana occidentalis) and the mountain bluebird (Sialia currucoides) face similar problems — and the suggestions made in this article apply to all three species.

Fortunately, the situation — while quite serious — is not irreversible. People who live in "bluebird country" can counteract all of the major threats to this species' survival — by not using chemical pesticides and herbicides, by building appropriate nesting boxes, and by monitoring those houses to evict any unwanted avian competitors.

A Bluebird Bungalow

It's not at all difficult to build a shelter that will attract members of the Sialia genus. However, the abode must be specifically designed to accommodate the tenant that you're seeking — and to discourage occupancy by the bird's rivals. The accompanying illustration (see Image Gallery) details the construction of a bluebird nesting box.

I've found that the front of such a house is the most important component of the entire structure. After the "starling proof" 1 1/2-inch-diameter hole is drilled (angle it slightly upward to prevent rain from getting in), the interior of the panel should be grooved — horizontally — with a chisel or saw. These "steps" will give the fledglings a means of leaving the dwelling when they're ready to try their wings.

Once the front piece is finished — and the other main sections have been cut to shape — it's time to begin the actual assembly of the home. I find it easiest to attach the sides of the box to the back first, and then install the bottom — making sure that the sides and back extend a quarter inch below the base piece so that water won't run down the outer walls and collect in the center of the bottom before dripping off, possibly soaking through the floor and wetting the nest in the process. (By the way, if you use wood screws and glue — rather than nails — to assemble your nest box, it will likely have a longer life expectancy.)