Purple martins and humans have benefited from each other for centuries. This beloved species of songbird prefers to nest in cavities found in cliff facings, trees and manufactured habitats that provide the perfect conditions for breeding, shelter from the elements and protection from predators. Purple martins feed on a variety of flying insects, catching their prey during flight. During the cold winter months, they migrate to tropical climates, and they return in the early spring to mate and form their families. Making a gourd birdhouse can help them.
Choose a gourd that is at least 7 inches in diameter. The Zucca, kettle and Chinese bottle varieties are good choices for use in making gourd birdhouses. Ornamental (hard) gourds often are available at farmer's markets and retailers, and you can grow your own.
Dry the gourd thoroughly. If you grow your own gourds, allow them to harden off while still attached to the vine for best results. Gourds are ready for harvest when the vines and leaves die off and the outer skins are solidified. When cutting gourds from vines, leave at least 2 inches of stem on the gourds.
Ventilate the gourd. Place it in a well-ventilated area, preferably outside. Air flow is essential for properly dried gourds, and the outside elements will not harm gourds as they continue to dry. Lagenaria gourds can take three to six months to dry, while the Cucurbita varieties cure within two to four weeks. When the outer skin hardens and the seeds rattle inside, a gourd is dry and ready to be cut and hollowed.
Clean the gourd with a weak solution of bleach and water, using 1 part bleach to 4 parts water. Use a scrub brush to remove clumps of dirt.
Roughen the surface of the gourd with sandpaper to allow for better adhesion of paint.
Brush a coating of water sealer on the gourd and allow it to dry completely.
Brush on one or two coats of a white or very light-colored pastel acrylic or high-gloss enamel paint and allow the paint to dry thoroughly.
Make a hanger for the martin house. Drill a 1/4-inch hole through the stem to use for hanging the gourd birdhouse. Insert wire through the hole, and then determine how much will be needed to hang the birdhouse. Snip off the wire and twist its ends together.
Drill four or five holes In the bottom of the gourd for ventilation. Use the 3/8-inch bit to make the holes.
Saw the entrance hole. After marking the midpoint of the bulbous portion of the gourd, use a hole saw to cut a 3-inch entrance hole, placing the center of the entrance hole over the midpoint mark.
Clean out seeds and pith from inside the gourd with a serrated knife.
Cut a 4 1/2-inch hole at the top of the gourd's bulbous portion on the opposite side of the entrance hole. This access hole will be used to monitor martins and for cleaning.
Insert a pre-manufactured access cylinder into the access hole and line the perimeter of the hole with adhesive caulking to attach the cylinder to the gourd.