I bought my first red tail boa yesterday. He/she is very young, and I've always heard that you should not use cedar or pine for boa substrates. The substrate that was sold to me with the snake is from Zilla, called 'bark blend'. Upon further looking today, the back of the package says "100% douglas fir bark." Correct me if I'm wrong, but isn't douglas fir a type of pine? Or is it ok to use the bark and not the actual shavings?