?? on my new meican pine snake and bullsnake

[Skiploder]

All colubrids will rattle their tails as its a defensive behavior that most grow out of once older. If not mistaken they are not rear fanged at all, as rear fanged are considered semi venomous snakes and pines are not. They do have teeth just their not large, but will draw blood.

Pine snakes can be very aggressive when younger but with time and settle in period they can get better over time.

Hmmm. I have many, many colubrids and most of them rattle their tails as adults.

There is no such thing as semi venomous. You either are or you aren't. Pits aren't. Most species of colubrids, whether rear fanged or not - are.