Avatar Rotation Control [UnityScript]

Hey everyone, I'm working on a school project and we're engineering some flight controls into our main character (a pigeon). I have the guy flying around and making a banking motion with GetAxis("Mouse X") and GetAxis("Mouse Y") and then utilizing the Transform.Rotate on the Z axis to have the pigeon tilt on it's sides.

I'm wondering if there's a method to limit how far the pigeon rotates (like measuring the degrees that it goes). I would love to have it translate it's transform upon hitting a certain degree of rotation and that's what I'm after more than anything.