Reprinted from: Purple Martin Update 7(2): 10-12
James R. Hill, III
Purple Martin Conservation Association
Properly prepared gourds make excellent nesting quarters for many species of native birds. One drawback to gourds, however, is that compartment access is limited to what can be seen through the entrance hole. Nest access is desirable for monitoring, cleaning, and replacing nests for parasite control. Landlords who use gourds should try the following "remodeling" projects.
How to Put Access Doors on Gourds
Photo #1: The threaded necks and lids of plastic jars make excellent access doors. A jar with a 4-inch opening is recommended. Many brands will work; we have used Anchor Hocking Klear Stor® 1/2-gallon round plastic container (No. 20014), and Rubbermaid's® Servin'Saver 3-quart, plastic jar (No. 3101). A jar with a slightly rounded shoulder is ideal; jars with straight necks and sides would not work as well. To find an inexpensive source of jars, check WalMart, K-Mart, or the PMCA has them in 6-packs.
Use scissors to cut the top portion off the jug an inch below the neck flange, as shown by the black dotted line in photo #1. Start the scissor cut by first puncturing the jar with a razor blade knife. With the lids still screwed onto the necks (so no paint gets on the threads), spray the inside and outside with quick-drying black enamel paint. Apply two coats to make the neck/lid assembly completely opaque.
Photos #2 & 3: Take a cured gourd and drill an entrance hole using a 2&1/8" hole saw. Center the hole on the equator of each gourd. You want the entrance hole to point straight out, not up or down. To find the location for the access door, take a cut-off jar neck and place it on the upper right side of the gourd (for right-handers), or left side (for lefties). It should be placed slightly above the level of the entrance hole, pointing up, as shown in the photo. Mark the center for drilling, and drill the access hole with a 4" hole saw. Use a consistent location for the access door on every gourd. Scrape the seeds and dried guts from the gourd, then wire brush and sand the exterior. An electric palm sander works best. (The gourd on the left of photo #3 is unsanded, the gourd on the right, sanded). Drill seven 5/16" drain holes in the bottom of each gourd, and a set of hanging holes through the neck. Soak each natural gourd in a copper sulfate bath for 10-15 minutes (1 pound of CuSu dissolved in 5 gallons of water) to preserve it. If you can't locate copper sulfate at a farm supply or garden store, Thompson's Waterseal can be applied to the interior bowl of the gourd. Do this before attaching access doors and canopies.
Photo #4: Center the jug's neck over the 4-inch hole and use three or four 3/8" long, #8 sheet metal screws to secure the neck to the gourd. Drill or poke pilot holes first. Space the screws evenly around the plastic neck, 1/4" in from the neck's outer edge; be careful not to tighten the screws so much you warp the jug's neck, or the lid will no longer screw on. Any gaps left between the gourd and the jar neck will be filled with caulking, so don't try to eliminate gaps with more screws.
Photo #5: Use only 100% silicone caulking. We recommend DAP 100% silicone caulking (or its equivalent), the kind that is white, paintable, and cleans up with water. Apply a 1/2" thick bead around the edge of the jar neck, where it meets the gourd. Use more caulking where there are large gaps. Smooth the caulking with a brush, but do not brush it out too thin. Be sure to cover the screw heads. The photo shows an access door with the caulking brushed smooth around most of the neck.
Photo #6: After the caulking has dried for 24 hours, hold the gourd up to a bright light and look through the entrance hole. If you see any light leaking in around the access door, apply a final coat of black spray paint, as shown in the photo.
How to Put Canopies on Gourds
Another way to improve gourds is to add a canopy above the entrance hole. Canopies lessen the amount of rain that will get in a gourd, reducing egg and nestling chilling. Canopies also provide an additional perching area for the martins. And some people believe that gourd canopies may increase protection from owl predation.
Landlords can cut, file, and bend canopies from a sturdy stock of sheet metal, or they can
order them from the PMCA's Martin Market Place catalog
. Dimensions recommended are 6-7" long, by 2" wide. Taper off the outer quarter of the canopy at both ends with tin snips, and file any rough areas along the edges. Bend the canopies to the desired curvature, by shaping them over a V-8 can, or other round surface.
Canopies can be attached to any gourd, natural or plastic, with just a thick bead of 100% silicone caulking. Make sure that the gourds are free of dirt, mold, and surface flakes. For natural gourds, lightly sand the areas above the entrance holes where the canopies will be attached. If you are mounting canopies on gourds that are already painted, you will want to roughen-up the surface, first, so the caulking will grip tighter.
Photo #7: Position the canopy above the entrance hole of the gourd about 1&1/2" to 2," as shown in the accompanying photos, so that martins perched in the entrance holes have plenty of head room. Once you have the canopy in position above the hole, trace its outline with a pencil or felt-tipped marker. Don't worry if there are small gaps between the canopy and the gourd - this is normal due to the irregularities in the surface of gourds. The caulking will take care of gaps.
Photo #8: Set the canopy aside and apply a 1/2" diameter bead of caulking on top of the entire length of the pencil mark.
Photo #9: Press the canopy into the caulking bead as far as it will go, along its entire length.
Photo #10: Use a 1-inch brush to smooth the caulk around the upperside of the canopy and a 3/4-inch brush for the underside. Allow the caulking around gourd access doors and canopies to dry for at least 24 hours before proceeding.
Photo #11: We recommend that you paint natural gourds, access doors, and the canopies white. Start by applying a coat of Oil Base Primer to the outside of the gourd, the entire canopy, and the access door, but be careful no paint gets into the threads of the neck and lid. (Use Exterior Latex Primer for plastic gourds). After it dries, apply one to three coats of white Elastomeric Coating, which is weatherproof and of insulative value. (Update 7(1) has an article on painting gourds and houses with Elastomeric Coating. Send a self-addressed stamped envelope for a copy of the article if you don't have that issue). If paint is used instead of Elastomeric Coating, use a good grade exterior latex semi-gloss enamel house paint, and latex primer. If the canopies are made of aluminum, they will not rust if left unpainted, but painting is recommended. If you attach these canopies to plastic gourds, painting is optional, but we would recommend it to protect the caulking seal. As shown in this photo, we paint the canopies and access door edges with contrasting trim colors.
Photo #12: PMCA summer intern, Scott Melego, has lowered a gourd rack and is counting the eggs in this martin gourd, modified with an access door and rain canopy. Through these removable lids, landlords are able to count leaf-buried eggs, accurately count nestlings, remove nestlings for banding, remove blowfly-infested (or wet) nesting material (and replace it with clean, wood shavings), and easily clean out gourds at the season's end. Landlords should never leave nests in gourds between seasons, or leave them hung outside during the winter, as both will greatly shorten the life of the gourd. A properly-preserved gourd that is kept painted, cleaned out between seasons, and stored inside over the winter, can last for over 30 years. Some of the PMCA's gourds have been in use for close to fifteen years.
James R. Hill, III, is Executive Director of the PMCA.
Copyright 1996 by Purple Martin Conservation Association. All Rights Reserved.
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