Also you CAN only feed them once a month and yes they'll survive but its not healthy. There are members on here who have lost snakes for months on end and there's no certainity of when and what they ate so it is possible but it's not what is the best for the snake. If they are really 4' long and over 2 years old then you'd be best feeding them once every two weeks, but get a weight on them if you can because they may be underweight at the moment and you may want to feed them sooner than once every two weeks for a while until they get a little bigger again. If you can get a weight on them then search "the munson plan" and it will give you an idea of what to feed them at their current weight.