Natural selection. Is it working?

Apparently not, if you live in my backyard. Every spring, for the last five years, since we built this pergola in the backyard, birds have been trying to build nests in it. The unfortunate thing for them, is that the spaces are way too small for a nest remain. But, every year, birds belonging to what I have to believe are descendents of the same line of birds that lay claim to our little backyard as home, continue to futiley attemp to create a domestic space in a space that is uninhabitable. Every year they attempt to stuff grass and leaves and paper towels that they find in our recylable bins into the niches and crannies of the pergola, only to have the stuff fall on to the ground thirty seconds later. Come June, as a result, our patio is littered with grass clippings, weeds and string that the birds have gathered to craft their nests with, but that end up on the ground instead. I have watched, for whole half hours, this process, until I give up in disgust at the stupidness of the bird. How it can not realize that, no matter how hard he tries, his nest will not stay put, is beyond me. I have even gone out, and behind the birds back cleaned out the niches with a hose, hoping that they will get the message that the space they have choosen is a disaster zone waiting to happen. About as smart as building a house in Lagoona beach, that is just waiting to slide into the ocean at any given moment. But, the birds, they never get the hint. Relentlessly, they return and continue to make nests. Personally, I think it has the earmarkings of the work of an overeager male bird. Some pregnant bird is sitting in a near by bush yelling at its mate to get a move on and make her a decent nest. While I appreciate his desire to please his mate, couldn't he finally understand that there is a more comfortable nest to be made in a tree nearby. You would think that after generations, the stupid gene would be eradicated from this particular family of birds. But, no. Apparently, stupidness never ever seems to be fully be removed from any of the gene pools.