My pond is filled by rainwater. I live in the deep south of La. The bird theory makes sense around here. We have open ditches, crawfish ponds, swamps, canals in all directions and a huge Egret and herring population that being said Mr. Lusk would know better than i would.
Pretty sure the catfish that i didnt stock are CC. The sunfish are a decent size ( ill take pics soon) so i dont mind having them but i thought, like you said BG would spawn more often and they are also fun to catch.
Honestly im not so much trying to build a balanced pond but more of a CC pond with a few other species. My pond isnt large so im sure there is only so much that i can do.
I enjoy chatting with like minded pond owners so thanks for the responses!