-All- snakes are carnivores, but not all eat rodents. There is an amazingly wide array of snakes that specialize in eating various things, from eggs to lizards, to fish, to slugs. There are even species that specializes in feeding on snails, and some eat only termite and ant larvae.
You will never find a snake stalking a bowl of baby spinach unless there is something else in it...
That being said, I've often found that posting pictures of snakes feeding nothing more than a gratuitous grasp for attention. Something for blatant shock factor that all too often ends up pushing the stigma that snake owners are irresponsible. Especially on a forum where the snake owners are in the drastic minority. I'm all for using it an educational way, and explaining little things like how you buy your rodents pre-frozen, and so forth, but no one posts a picture of their dog with its face in a food bowl to get people to look, because it just doesn't have the same shock value.
Of course, not saying this is the case here, but there are more tactful ways of covering a topic which could be disturbing to most of the people who will see the thread.