I live in NW Arkansas and have purple martin colony consisting of 7-12 compartment aluminum houses. Last year I had 73 nesting pairs, and raised over 300 young. I have had problems with owls attacking the martins for the 12 years we have lived here. I have installed owl guards on all the houses. It keeps them from getting the young out of the nest, but I still had owls sitting on top of the houses that would grab the adults when they came out of the nest early in the morning. I have tried everything including lighting up the area, turning on a radio all night, but nothing worked. I saw your ad in the Nature Society News, and ordered 4 of the Nite Guards as suggested for owl. I put them up the same day I received them and after figuring out the best height for my colony (I did reposition the height 3 times)… I’ve been using my Nite Guards to protect my purple martins by mounting them 8-12 inches above the purple martin house. The results have been tremendous! They definitely work! Now I am able to get some sleep at night. Thanks so much for a fine product.