Black Snake Leaves a Calling Card

We have a small strawberry bed which produces abundant quantities of tasty fruit. Every year we get to enjoy the fruit for about a week. We pick the ripe strawberries in the early evening and have them with dinner each night. They are really better than the store bought fruit. The reason we only get to enjoy them for a week is something discovers them after the first week and strips the plants of both ripe and unripe berries. We suspect a black snake, rabbit or squirrels. This year we found some evidence that it may be the black snake as last night we found a 5 foot snake skin tangled in the strawberry plants. This is the first completely intact skin we've found