By Mark S. Sasser, Wildlife Biologist, Division of Wildlife and Freshwater Fisheries
Gourds are a sure sign that fall is here and now is a good time to purchase and prepare gourd birdhouses for the upcoming spring. A Gourd is still one of the best and most economical birdhouses you can find. Prices generally run from $1 to $2 each when purchased from a grower, harvested straight from the field.
Some growers and suppliers sell gourds pre-drilled and entrance holes pre-cut, but expect to pay $4 to $5, maybe more, for each prepared gourd. If you purchase gourd houses painted and decorated, like the ones you see at local flea markets, expect to pay even more. With a few small tools, it is a relatively easy task to make your own gourd birdhouse. Simply cut the proper entrance hole, drill a few drain holes in the bottom, drill a hole at the top and run a wire through the hole, and it is ready to hang.
While traditionally used for attracting purple martins to your home, gourds can attract other cavity-nesting birds. You can enhance the opportunity for attracting certain bird species simply by the size of the gourd, the size selected for the entrance hole, and the location and height above the ground. Another important factor that will greatly affect the type of bird attracted to the gourd will be placement associated with availability of habitat. For example, a group of gourds with a 2-inch entrance hole placed in a field or opening will likely attract purple martins, whereas a single gourd with a 2-inch hole placed in a wooded area is more likely to attract a red-headed woodpecker.
Select the size gourd from the grower that best suits your needs. Large gourds are the best for purple martins, while smaller gourds work better for bluebirds or wrens. If the gourd has not been harvested long enough to be seasoned, dry it by placing in a sunny area and turn it every few days until you can hear the seeds rattling when you shake it. Once it is completely dry, you are ready to begin preparation.
To prepare a gourd for a birdhouse, begin by marking a proper sized entrance hole. Be sure the bottom of the entrance hole is not too low to the bottom. This will prevent fledglings from falling out of the gourd before it is time for them to leave the nest. Cut out the hole with a keyhole saw, jig saw, or use a hole saw bit with your drill. I prefer a hole saw bit because it is quick and makes a smooth, uniform hole. Bore several ¼-inch holes in the bottom for adequate drainage. Clean out the dried seeds and drill a ¼-inch hole through the top, attach a wire hanger and the birdhouse is ready for hanging. A gourd birdhouse will usually last two years, but for added protection and longevity, varnish or paint with a light-colored paint to prevent overheating.
Research has shown that gourds are superior homes over commercial houses for some species for a variety of reasons. Weather is a major cause of mortality in many bird species, especially purple martins. Natural gourds offer better insulation against heat and cold than aluminum or plastic housing. My personal observation is that martins always prefer natural gourds over any other type of commercial houses. When given the choice, they will always nest first in a natural gourd before using an aluminum house or plastic gourd.
Studies using sophisticated temperature probes have shown that martin nests in natural gourds stayed cooler in hot weather and warmer in cool weather. These same tests have consistently shown higher occupancy rates (100 percent) of natural gourds over conventional houses (67 percent). Often heating up to higher temperatures, which can affect hatching and nesting success rates, aluminum houses and plastic gourds do not possess these same insulation qualities for the nestlings as natural gourds. Natural gourds also provide a larger, deeper nesting compartment for martins than the typical 6-inch by 6-inch compartment houses available from birdhouse suppliers. These deeper nesting cavities offer better protection against predators and reduce egg losses. All of this adds up to martins having their highest reproductive success in gourds.
All of the birds listed below are cavity nesters and will use gourds if positioned and hung properly.
Diameter of Hole
Height above Ground
1" - 1-1/4"
2” – 2-1/2”