King snakes in the wild eat a variety of prey, from rodents to birds, amphibians to lizards and even, frequently, other snakes! In fact, they will eat each other if kept together so these snakes must be kept alone in their cages. Pre-killed mice or baby rats are usually the main food fed and always make sure that the size of prey does not exceed the width of the snake (excluding the head). Adults may only need to be fed once a week but juveniles will need to be fed at least twice a week.
Most healthy reptiles shed regularly, usually every 4-6 weeks, and this may coincide with greater or lesser appetite. Many reptiles will loose their appetite during this period and this is normal. Some will simply reduce their food intake while others will stop eating altogether until after they have completed the shed. Unless they still refuse to eat several days after a shed is complete, there is no need to panic.
Check the environment – maintaining the thermal gradient is very important as reptiles are “cold-blooded” and cannot generate their own body heat, so they have to rely on external temperatures to regulate their internal temperature and manage their metabolism. In the wild, they have the choice of moving into an area with the temperature they need (eg. sun or shade), changing locations and adjusting temperature as necessary. In captivity, therefore, they need to be provided with an artificial thermal gradient. This is particularly important to ensure the maintenance of certain key processes such as digestion of food. Make sure also that the reptile has the right humidity levels and adequate places to hide – lack of secure places to hide can place a reptile under stress.
Sometimes, if both the physical and social environment are satisfactory and there still seems to be a problem, it is worth looking beyond the enclosure, to the area it is situated in. For example, it is in a very noisy room with serious disturbance from children and other pets, which might be regarded as predators? (eg. cats and dogs). Has there been a major disruption of the reptile’s normal schedules and lighting, temperature or humidity levels, due to events like moving house, going on holiday or long-term visitors?
Ultimately, if you have considered all environmental factors and the king snake is no in the process of shedding, then it is not normal for a king snake to stop eating. Loss of appetite and refusal to eat is a behavioural change that could be indicative of stress or illness so the best thing is to take your reptile to the vet for a thorough examination.