Well, after many years of trying, and the last seven educating myself, I finally have a pair nesting this year. I have been blessed with not only a nesting SY pair, but also, an unmated SY male. Both these SY males are very aggressive. They will not tolerate any other type of bird, with the exception of making peace with my Bluebirds, to spend any time on "their" rack. I have seen them attack, and take to the ground in bitter battle, Mockingbirds, an Eastern Kingbird, as well as attack Mourning Doves, Great Crested Flycatchers, English House Sparrows, House Finch, and at least one starling. Last year, I tried an experiment that seemed to show immediate results. I put up 18 UNPAINTED natural gourds. Every visitor I had last year only paid attention to these gourds. They totally ignored all my white gourds, both natural and plastic. By the end of the season, the unpainted gourds had turned a chalky white color on the outside surface, so I decided to paint them. I cleaned a piece of gourd, and carried it to Lowe's. I came up with a match of Valspar American Traditions Exterior 100% Acrylic Gloss House and Trim paint. The color was Majestic Oak. This year I put up 36 of these painted gourds. I had 22 on one rack that holds 24 gourds. The other two gourds on that rack were a Troyer Horizontal Plastic Gourd. The rest of the Oak color gourds were scattered among my 3 other gourd racks. Again, this year, most all of the attention was paid to the brown gourds. Some attention was paid to a few white natural and a Troyer Horizontal. The pair that nested chose an Oak colored gourd.