Songbird Essentials PMCA Excluder Ultimate Gourd Round The PMCA Purple Martin Conservation Association Excluder Gourd helps safeguard the purple martin from European starlings. Two patented entrance holes U.S. Patent number 6513454 and the crescent exclude the European starling from nesting. Closure cap allows for nest inspections. Install the porch 5/8 inch distance from the bottom of the entrance hole to discourage starlings from trying to get inside. External owl and hawk guards may be purchased as an accessory item. The new Excluder Gourd is the first manufactured product to offer pre-punched excluder entrances. In Use Dimensions of the Gourd 10.50L x 10.50W x 12.00H. This item ships from a separate warehouse and may require extra time for delivery.