From: Ken Kostka, PMCA, Edinboro, PA
Date: 3/2/00
   
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Great Horned Owls (GHO’s) are a major night-time predator of both house-nesting and gourd-nesting Purple Martins. When raiding gourds, GHO’s will hover in front of the gourd, grab the entrance hole with one foot, reach in with the other, and attempt to extract martins or their young. Sometimes they just beat their wings against the gourd and snatch the terrified martins as they are scared out and attempt to escape. Since GHO’s are nocturnal and secretive, most people aren’t even aware that they’re in the area. GHO's often leave little or no evidence of their raids, so unless a landlord is doing 5-7 day nest checks (or prowling around their property in the middle of the night, like me), he/she won't even be aware that owl predation is occurring. The PMCA encourages all landlords with active colony sites to equip their houses or gourd racks with owl guards. If installing guards for the first time, wait until the young have hatched. Install the guards early on a fair-weather day after the young are 2-3 days old. The martins’ urge to feed their young is very powerful and they will soon overcome their suspicion of the guards and enter. Important: Prepare & rehearse the installation of the guards beforehand so that you can attach them fairly quickly once the time arrives. After the first season, the guards can be left on permanently since the martins will have become accustomed to them. Photo captions: Photo #1: Frontal view of gaurd. Notice how guard rods are about 4-6 inches apart at the level of the entrance hole. Photo #2: Frontal side view Photo #3: Side view. The distance between the ends of the guard rods and the entrance hole is 7-8 inches, plenty of room for a martin to fly up under the guard. Photo #4: Metal dowels are attached to rack arms using hose clamps. Click here for another article in the Forum Archives with photos of gourd owl guards Ken Kostka, PMCA |
