Snake Egg Incubation
Dr. Jenni Bass
Once she begins to lay, all eggs should be produced within 24 hours. If the eggs stick together, do not try to separate them. Remove the eggs to the incubator, taking care not to rotate them. Reptile eggs lack the rope-like structures called chalazae, which anchor the yolk of a bird egg and turning the egg may cause the embryo to be crushed by the yolk.
The membranes within the egg and surrounding the embryo and the blood vessels may also be more susceptible to the shearing forces that result from egg turning once incubation has begun. Most breeders will make a light pencil mark on top of the egg to assist in its orientation. This is also a way to identify each egg, for purposes of record keeping.
Bury the egg halfway into the moistened substrate. If you are incubating multiple clutches, identify the plastic container holding the eggs. Place a thermometer at the level of the eggs. If more than one species is to be incubated, they should be in individual incubators if possible to minimize the risk of disease transmission and allow for refinement of incubator parameters.
The eggs may take on a mottled or "chalky" appearance, but there should be no darkening or collapse of the shell or fuzzy mold growth. Viable eggs are firm, slightly pliable, dry and white. The presence of mold usually indicates fetal death, while a collapsing shell indicates dehydration. If you observe dehydration, assess the moisture content of the substrate, and add more water if necessary. Consider also whether or not the ventilation might be excessive, which often leads to dehydration.
After 2 to 3 weeks (earlier with experience) candling can be used to assess whether or not the egg is fertile and alive. Candling involves holding the egg, with its orientation unchanged, over a bright light source in a darkened room. It is helpful to focus light on the egg by holding the light source under a sheet of cardboard, for example, with a hole cut in it, which is slightly smaller than the egg. You may be able to see a dark area, representing the fetus, and an organized web of blood vessels.
Experience is required to become proficient at candling. Eggs develop, or in the case of infertile eggs, decompose, in different ways, so it will not necessarily be obvious which are viable and which are not. In addition, reptile egg development rates are notoriously unpredictable, and handling the egg may well jeopardize its health. Unless performed by an experienced breeder or veterinarian, candling should not be undertaken more than once every three to four weeks.
Candling is a fascinating learning process, but the risks must be weighed against the potential for harm. And unless you are certain that the egg is non-viable (hard, dry and the yolk rattles) it should go back into the incubator, just in case. If you are sure of egg death or non-viability, remove the egg in question, as it may become a source of bacterial contamination, infecting other eggs.
Sometimes snake eggs will stick together after they have been laid. Do not separate such eggs, but monitor them especially closely at hatching, as the young snake may break through (pip) into the attached egg. If a viable egg is attached to a non-viable egg, do not separate them. Check the eggs daily, several times daily when close to hatching. Most of the eggs in a given clutch will hatch within 24 to 48 hours of one another. The snake pips with his egg tooth (caruncle), which is located at the level of his nostrils and will be lost after hatching. Usually the snake will pip at the top of the egg, and he may stay in the egg for 48 to 72 hours after pipping, in order to absorb the remainder of his yolk sac.
There are no clear rules as to when to assist, but a snake that has not pipped within 48 hours of his clutch mates should likely have his shell slit for him. This carries some risk and must be done with care. A snake that is too weak to pip will die without assistance, but slitting the shell may damage the hatchling or the membranes and yolk which sustain him. One cannot be certain that the snake is simply not yet ready to emerge; as a guide, the last egg should pip within 48 hours of the first. Seek the help of an experienced breeder or veterinarian if necessary. Leave the snakes in the incubator until they have vacated their shells entirely. Newly hatched kingsnakes should housed separately as soon as possible, as they often show cannibalistic behavior.