Yes I noticed the color too. I have seen several coachwhips, both in the wild and in zoos, and they have been either all black or all red. I have not seen one like this that is half and half.
The outcome is the snake kept going along the fenceline trying to find a way out. Eventually the bird gave up and left it alone. I think the snake found a hole near the fence to retreat into.
I rarely go in the aviary, but many years ago I was in here and also saw a coachwhip.
