we have had a LOT of snakes this year, I have found 6 large black snakes in my coops eating my broody hens clutches. I love snakes and love to have beneficial ones hanging around. Snakes may be beneficial, but if they are gobbling up your livestock, you are well within your rights to remove them just as you would any other preditor.
These snakes WILL eat your eggs and very young chicks, you need to decide about how you want to remove them. I would suggest removing them because even if you don't mind loosing an egg or two, these preditors terrify your older chickens. The snakes that are too large for the chickens to kill and eat -- especially the ones that take over a nest and proceed to eat all of the eggs -- these snakes will seriously stress a broody hen or even a small group of chickens. I found this to be true particularly when she is alone in a box. The snakes big enough to eat eggs and young chicks are typically not snakes that your normal docile hens will attack, especially if the hens are confined in a small area and cannot get to what they feel is a safe distance.
I relocated mine, if you do that, you have to take them a good ways off, just the other side of the field isn't far enough. Put them in a sack and take them at least 5 miles away. Otherwise they will be back tomorrow. I always prefer to relocate rather than kill a beneficial snake, but if you are not sure if its poisonous use extreme caution.
One person mentioned snake proofing your coops. I would love to hear how they successfully did that. Sulfer, tin foil, even greasing the raised coop legs and sealing off every hole except for the chicken wire still has not worked for me. I did find one fat eggs-in-the-belly shaped snake curled up in the corner of a coop one morning. The hen was as far from it as she could get, panting, wide eyed, and wheezing. I think that snake got in while skinny, and could not fit back out. He moved to a swampy area miles from here! We are not all in a position where we can successfully snake proof...
I have even placed "bait" eggs and watched for snakes as for a while I had a new one or two every day.
happy to talk privately about this if anyone is interested in continuing the conversation outside the forum.
Someone asked about cross breeding snakes . . . no, venomous species cannot breed with non venomous ones. Certain species can cross, but it seldom occurs in the wild, and only amongst species that are VERY closely related.
Most snakes tend to be specialized eaters, meaning egg eating snakes eat eggs, mammal eating snakes eat mammals, and so on. Certain snakes, such as certain hog noses, will die if they eat anything other than what they were designed to eat. King snakes evolved to eat reptiles. In captivity they can be trained/forced to eat mice, but eggs and chicks are perfectly safe as far as possible menu items for a wild king snake.