I noticed that. I see that happen with rattlesnakes. People up here kill every rattlesnake they see. There will just be another that comes the next day. I found putting bull snakes in that area seems to drive out the rattlesnakes. The bull snakes out compete the rattlesnakes. When the rattlesnakes aren't getting any luck they move on. The neighbors that kill them all, are constantly at it until fall. I just collect the bull snakes and never see rattlesnakes after May. But I can't convince them at all.when you create a vacuum someone will flow in to fill it the time of the year dictates how fast that will happen .