Part of the "survival of the fittest" theory involves being able to raise your young successfully. If these birds weren't particularly good next builders, then their young will die and they won't be passing along their inadequate genetic material. If they learn from this mistake and figure out how to raise their young by bolstering their nest and building it further away from cat predators, then they'll be smart enough to reproduce.

Darwin in a nutshell.

I'm going to put some purple martin houses out in the yard this year, in preparation for next spring. They do a wonderful job of eating mosquitoes. (I plan to have a house, not gourds. My neighbor has a couple of them going and has offered to advise me when I'm ready to put it up.

SRS