The best protection from snakes that we have found, and we sure do have them here in Texas, is cats. I am lucky enough to have all four of the venomous breeds, copperhead, water moccasins, rattlers and coral right in my back yard. We tried dogs first, but they were also interested in the chickens, our cats make friends with the chics, or at least play with them without injury. The cats will go after anything that wanders up into the yard or garden area. Never lost a cat yet, although we have seen what we believe were snake bite on their heads, swelled up area that went away in a few days. One draw back is that sometimes they like to bring us presents, mostly disarmed from movement to the door, the kitchen, our bed.
I will be keeping a closer eye on the flock myself until I feel like the situation can be explained better. The kids do most of the work, but sometimes overlook things. I will let you know if we find evidence of what happened. Thanks again to all that helped.