I do not require signatures on my packages for that specific reason. I don't want to sound like I don't care about my customers, but you should be home and expecting the delivery. So, if you have not seen the package by 10:30am, check the porch, as it should be there. I do know that they have left some of my boxes on a doorstep before, when the customer was home, but they typically try to put it in the shade, because it says perishable all over the box.
I hope your snake is alright.