Purple martins -- birds who eat their weight and more in insects -- are some of the most beneficial songbirds in the United States. Their diet consists almost entirely of small
flying insects.
 
These graceful fliers reduce insect pests in gardens at an incredible rate: a pair of purple martins and their young will consume 15 pounds of insects in a summer.

Unfortunately, their numbers are in decline.

Purple martins overwinter in the tropical rainforests of Central and South America. As the rainforests continue to diminish through extensive logging operations, purple martin populations nesting in the United States have also declined. Providing suitable nesting sites in South Carolina can delay, and possibly reverse, this decline in the purple martin population.

Purple martins are migratory birds, arriving in South Carolina to claim nesting sites as early as mid-February.

"The earliest date I have recorded my first arrivals was on February 9," said David Bradshaw, Clemson Extension horticulturist, "but purple martins continue to arrive throughout March and April."

Members of the swallow family, purple martins catch their food on the wing. They are gregarious, preferring to nest in large colonies near human habitation, and they like open areas well away from trees.

"Just in my own experience, purple martin populations have dropped," Bradshaw said. "I once had two colony poles with 48 gourds with between 30 and 40 pairs of martins nesting near my vegetable garden. Now I only have 24 gourds, with four nesting pairs last summer."

He said that with most pairs fledging from four to seven young, there were often more than 200 birds flying around catching insects before they migrated south in late July and August.

Bradshaw enjoys their clear metallic and musical songs in daylight hours throughout the nesting season. An additional benefit of having purple martins is that they are vigilant sentries who guard against hawks and crows, chasing them from the vicinity of
the colony.

Purple martins drink while on the wing, skimming over lakes to scoop up water. Therefore, the colony will enjoy a greater chance of success if it is placed within a quarter of a mile of a lake or pond.

"I have even seen colonies attached to boat docks," Bradshaw said. "The birds seem undisturbed by frequent boating activity."

To make purple martin houses, or condominiums, you can use "birdhouse" or "purple martin" gourds and galvanized pipe. The following instructions include refinements Bradshaw has made on his own colonies over the 40 years he has enjoyed attracting
purple martins. For summer 2001, he is making a similar martin condominium for the Heirloom Garden at the S. C. Botanical Garden in Clemson.

To prepare gourds for hanging, cut a two and one-quarter inch hole about one and one-half inches above the floor of each gourd, using a hole saw attachment on a hand-held electric drill. This can be done manually with a sharp pocketknife.

Remove all seeds and papery husks from the interior, and drill several one-quarter inch drainage holes in the bottom of each gourd. Drill two small holes near the top of the neck, about an inch apart, so you can insert a metal shower curtain hook. Now the new birdhouse is ready to be sanded free of flaking skin and mold before painting.

The base pole and upright for the condo tree are made of two to two and one-half inch galvanized pipe. The base pole is five feet long; the upright 15 to 20 feet long. Lighter materials like aluminum can be used.

"I drill holes through the upright, insert two crossbars and weld them into place for stability," Bradshaw said.

The crossbars are one and one-quarter inch galvanized pipe or conduit. After they are welded in place, drill holes on either side for one-eighth inch I-bolts and firmly attach the bolts with nuts and lock washers.

Set the base pole about three feet deep in the ground, anchored with concrete. Drill a hole through the top and bottom of the base pole and corresponding holes in the bottom of the upright, and bolt the two poles together. This design makes cleaning simple: just remove the top bolt and hinge down the upright.

"Then I slide a metal shower curtain hook through the two holes in the neck of each gourd to clip it to the I-bolts securely." Bradshaw said. "The hooks can then be snapped off in minutes for cleaning and winter storage in a dry place."

He said each spring he reattaches the gourds and applies a new coat of exterior oil-based paint. He uses paint that is white or tinted a light adobe gourd-color brown. When stored and painted annually, gourds may last five to six years.

Bradshaw said you can usually find people selling gourds this time of year at flea markets or advertising them in a Market Bulletin.

If you want to grow your own birdhouse gourds, they can be grown in almost any soil in full sunlight, but they respond well to added organic matter and moderate water. Plant seeds in early summer, after the soil is warm. Gourds grow rampantly with vines
20-30 feet long.

They readily trellis up chain link fences without help or attention. When gourds are mature and dry, they are naturally hollow and lightweight.

"The purple martin gourd seeds offered through S.C. Foundation Seed are the result of 40 years I've spent selecting gourds that make good birdhouses," Bradshaw said. "They don't crack much, so I've never had one of these fall down with a nest in it. Also, their necks are short, just right for the shower curtain hooks."

Seeds for purple martin gourds are available through S.C. Foundation Seed. Call (864) 656-2520, fax (864) 656-1320 or E-mail seedw@clemson.edu. View the catalogue and order form on the web at www.clemson.edu/seed .

CONTACT: Dr. David Bradshaw, Clemson Extension horticulturist, (864) 656-4949