Saw couple snakes in my yard over the weekend (non-venomous (rat and garter). They had eaten and yes I could tell. I leave them alone because when the neighbor gets his arse around to mowing his yard, we end up with rodents. My current yard guy is snake friendly and instructs his guys to move them and not mow them. He feels the same way. As far as anything getting to the couple humming bird feeders we have, DH just paints mixture of Vaseline, oil and iodine on the post so critters can't crawl up. It is also a deterrent to those 2 legged critters who feel it's ok to confiscate what doesn't belong to them and they can't climb the pole or just don't like the feel of the Vaseline mixture. When they leave, they often have this greasy, oily red mess between their legs. The smaller critters don't like the smell so they stay away.