Gourds, the dried, hard-shelled fruits of certain vine plants, serve as natural shelters for various bird species. Their sturdy structure and hollow interior make them suitable nesting and roosting sites. Humans have long used gourds to attract avian residents.
The Premier Gourd Nesting Bird
The Purple Martin (Progne subis) is the most prominent avian user of gourds. In eastern North America, these swallows depend on human-provided housing, including gourds, for nesting. This reliance dates back centuries, with Native Americans first hanging hollowed gourds to attract them.
Purple Martins are colonial nesters, preferring to breed in groups. Gourds offer individual compartments within a colony setup. Gourds should have a diameter of 8 to 13 inches, providing ample space for a clutch of 4 to 6 young.
Entrance holes for Purple Martins are typically round, measuring 2 to 2.5 inches in diameter, with 2 1/8 inches being a common size. This opening should be positioned 1 to 1.5 inches above the gourd’s floor. Several 5/16-inch drainage holes at the bottom and ventilation holes or added vents near the top prevent overheating and wet nests. Larger compartments also offer enhanced protection from predators.
Other Avian Gourd Users
While Purple Martins are the primary species associated with gourds, other birds may occasionally use them if modified. Smaller cavity-nesting birds such as wrens, bluebirds, chickadees, and some swallow species might consider a gourd. The specific dimensions of the entrance hole and the size of the gourd must match the requirements of the desired species. For instance, wrens might use a gourd with a 1-inch entrance hole, while bluebirds and tree swallows prefer a 1 1/2-inch opening.
Gourds are generally less preferred by these other species than by Purple Martins. Manage potential occupancy by undesirable species like House Sparrows and European Starlings. These aggressive non-native birds often compete for nesting sites and can pose a threat to native species if not properly deterred.
Creating a Gourd Habitat
Preparing gourds for bird housing involves several steps. Natural gourds need thorough drying and curing, a process that can take 3 to 6 months. After drying, the outer skin and mold should be removed by soaking and scrubbing, often followed by a bleach solution to sanitize.
Once clean and dry, gourds should be painted with light colors, such as white, to reflect sunlight and prevent the interior from overheating, particularly for Purple Martins. Drill three to five 1/4-inch drainage holes at the bottom to prevent water accumulation. Ventilation holes or added vents, possibly near the top, help regulate internal temperature and humidity.
Mounting gourds correctly is important for attracting birds. Hang them at a height of 10 to 20 feet in an open area, away from tall trees or structures, to allow birds easy access for colonial nesters like Purple Martins. Spacing between gourds is important for species that nest in colonies. Regular maintenance, including annual cleaning of old nests and ensuring proper drainage, helps ensure a healthy environment for nesting birds.