Snakes will often devastate colonies robbing the nests of eggs, young and even adults. Most of this occurs at night. Ken Kostka and Kent Justus pointed this out at:
If you have time give it a quick read and you’ll be convinced that sooner is better than later.
Chuck Abare is always trying to make things better for the purple martins so if you would like to protect your colony from the possible attack of a snake, you may wish to install one of his snake guards. This will be a good project our satellite colony at the Holiday Beach Community Site.