Breeding Milk Snakes

The successful breeding of milk snakes is a culmination of all we have covered so far plus some. Breeding procedures for most subspecies of milk snakes can be described as almost a "recipe". The following procedures are the steps of this recipe.

In the middle of October stop feeding adult breeders but maintain normal temperatures until November first.  If you live in a temperate zone, beginning in November, turn off all lights and heat sources to lower the ambient room temperature to 50F-55F.    In warmer climates a different approach could be used to get the desired 50F-55F room temperature.  Some of the methods used may include air conditioners, fans on timers that allow cool night air to blow in, and finally the use of thermostatically controlled coolers used to maintain wines at the appropriate temperatures. The latter, though expensive, will allow one to cool snakes within closely controlled parameters at any time of the year.  Because of the warm weather and high background temperatures of an area such as Southern California, it can sometimes take several weeks for the temperatures to drop to the desired level.  This can cause problems with some of the montane subspecies, but does not seem to adversely affect the breeding of most milk snakes.  During this cooling period, keep the reptile room closed and try to keep temperature fluctuations to a minimum to avoid respiratory problems.  Usually there should be no more than a ten degree variance over a two week period of time.  Herpetoculturists refer to this cooling procedure as hibernation, although is is considered to call it "brumation", based on the most recent research.  Most reptiles don't hibernate in the true sense because, even though their metabolism has slowed considerably, they can perform various levels of activity such as drinking and moving about.

However, the word brumation elicits associations that do not really fit from a herpetocultural point of view.  Indeed, brumation has not been widely adopted by the herpetocultural community and will probably not be.  It is a word that looks and sounds wrong.  The closest word to it in most people's memory is ruminate (not "brume", meaning winter from which it was derived).  Brumate and brumation in terms of popular use simply do not work.  It would make much more sense to expand the definitions of hibernation and hibernate to include the following:

hibernation: 1. a popular term used by herpetoculturists in reference to the winter cooling of amphibians and reptiles in captivity usually associated with reduced activity and fasting. 2. the process of being subject to reduced winter temperatures and the associated reduced activity and fasting (used with amphibians and reptiles in the reference of herpetoculture).
to hibernate: 1. a popular term used by herpetoculturists in reference to establishing environmental conditions and exposing amphibians and reptiles to environmental conditions leading to hibernation. 2. a herpetocultural term meaning to undergo the process of hibernation with reference to amphibians and reptiles in captivity.

The above is a position that has been developed and adopted by both the author and the publisher. The terms hibernation and hibernate will be used in the rest of the test in reference to the above definitions.

Standard maintenance procedures during this cooling period consist of changing the water once a week, regularly cleaning up any defecations, checking for sheds and shedding problems, and recording anything of note.

On March 1, turn the heat/lights back on and provide temperature gradients that offer higher temperature areas, but have a background temperature of 80F.  Within one week start feeding and begin introducing and keeping pairs together at least one day per week for mating.  Most of the milk snakes will shed at least once, some twice, after hibernation.  A female ready to breed shortly after her first or second post hibernation shed has a scent which is often highly arousing to males ready to breed.    Some of the subspecies routinely breed early in the season, some quite a bit later.   Some individuals will breed at different times than is considered "normal" for the subspecies, so watch each snake carefully, even if you don't expect anything at that time.  Sometimes you can feel or see developing ovarian follicles in a snake.  To feel for these follicles let the snake crawl between your forefinger and thumb.  Starting about mid-body, gently push your thumb up on the ventral surface until the ventral surface is pushed up into the ribcage.  As she crawls (if you try to slide your hand she may tighten up her muscles and you won't be able to feel the follicles) over your thumb you may feel a succession of round "bumps" evenly spaced.  They sometimes feel like those old "Pop Beads" jewelry.  If these hard follicles are present you can safely suspect she is ready to breed, has just bred, or will be ready to do so very soon.  A follicle is the part of the ovary where eggs develop.  It breaks open and releases the egg to be fertilized at a later point in time.  Be sure to have a male with her at this time.

Copulation times also vary greatly with the subspecies of milk snake.  Some are "quickies" averaging 10 minutes, some go well over two hours.  In many, the male will bite the head or neck of the female.  Most milk snakes will accept multiple "lovers", so it doesn't hurt to introduce a second male and try again.  You don't want to miss providing good sperm to a receptive female that has developed follicles, or you may end up with infertile eggs (slugs).  Unless you need the male elsewhere, leave him with "his" females.  The more matings over a period of time, the better your chances for a good clutch of eggs.

Try to leave the "male of record" with "his" females, or at least have him visit them for a day or two each week.  There are theories that suggest the first matings may simulate follicle development, and later matings or retained sperm actually fertilize the eggs.  Sperm can be retained by a female milk snake which she can use to fertilize her eggs even one year later.  However, there seems to be a relationship whereby the longer the period of time between copulation and egg laying, the greater the percentage of infertile eggs that will occur.  Preferably, there should be a fresh "batch" of sperm available for each new group of follicles to be fertilized.

When the female is visibly swelled with eggs (the rear third of her body becomes quite distended) and becomes opaque, record it (see Records) and remove all cage mates.    Prepare and introduce an "egg laying box" which can be any type of container that is large enough to comfortably hold the female, but small enough for her to feel confined and secure.  The egg laying box should have an access hole large enough for her to easily slip through.  It should also be about half filled with loosely packed damp (not dripping) sphagnum moss.  As a rule, female milk snakes will select this specially designed container as the egg laying site.  I have never had a milk snake choose the water bowl over the egg laying box for egg laying, but just in case, you may want to remove the water bowl, or lower the water level to 1/8"-1/4" depth, just enough for a drink, to play it safe.  Some breeders choose to remove the snake from her cage and place her in a special cage or 5 gallon bucket partially filled with damp moss and sealed by a secure lid (with holes for air exchange). After her "pre-egg laying" shed (see Feeding for the recommended food regimen during this time), record the date then wait 6-10 days (varies with the subspecies) for the eggs to be laid.  If you use an opaque plastic food storage container, you will be able to see the eggs through the container and won't have to keep disturbing the snake.

Once the eggs are laid, check the female for retained eggs.  If all appears well (she appears healthy and still has good body weight) then offer her several smaller food items.  Within three days, put the male back in with her and try for a second or third clutch of eggs.  It is preferable during this time to avoid feeding a female a large food item because when a male starts chasing her around to breed with her, she may regurgitate.  If the same volume of food is consumed during this time but in smaller portions (i.e., several fuzzy or just-weaned mice instead of larger mice), she will normally hold her food down.  When double clutching or triple clutching a female, it is a good idea to try to use the same snake who fathered the first clutch so that there will be no doubt about which snake fathered subsequent clutches.  Because of retained sperm and delayed fertilization there could be questions as to which snake actually fathered a particular clutch.

This procedure of collecting the eggs and feeding can go on as long as the females are willing and able to produce eggs.  Most subspecies of milk snakes will produce two clutches of eggs in a season.  One type of milk snake, the Pueblan milk snake, routinely produces three clutches in one season.  By late summer (Aug.-Sept.), female milk snakes have usually stopped producing eggs.  It then becomes important to feed them enough so that they regain their prime weight prior to hibernation.  Again, your records and the general condition and appearance of the snake will help you determine if you meet this goal.  Don't overlook the males at this time.  It is easy to miss a seasonal weight loss in the males as we don't pay as much attention to them.  This brings us to mid- October where we start the cycle again!

You may not have to hibernate all milk snakes; a slight winter cooling will work with some.  The above methods have been used successfully with milk snakes that are found from Texas to Central America.

The average female milk snake will stop producing viable eggs at about 10 years of age.    If it is important for you to produce a consistent number of babies each year, you need to take this age factor into consideration in your long term planning.   When your female is 6-7 years old you should hold back or buy a baby female to grow up as her replacement.  Males will perform slightly longer than females, but 10 years is a good general rule with them as well.  You should also hold back or buy male babies so there will always be young "studs" capable of servicing several females.

Every so often try to "trade out" or buy babies of known origin from other milk snake breeders so you don't have to interbreed siblings or related stock.  So far, in snake breeding, there are relatively few examples of the "inbreeding syndrome" (but there are some) associated with reduced vigor and genetic problems.    However, the "pros" are setting up the stud books for threatened and endangered species say it is important to have as much "founder stock" (animals traceable to their wild origin) as possible to prevent the problems associated with inbreeding.  This is another good reason for maintaining careful records on the snakes that we keep and breed.

Hatching milk snake eggs is simple.  You need four things.  You need fertile eggs, proper incubation temperature, proper humidity, and proper ventilation.  How you control these factors can be varied.  The proper temperature range for incubating milk snake eggs is 78F-88F with a preferable range of 82F-85F.  If you are on the cooler side it will take longer for your eggs to hatch.  If you incubate the eggs at too low of a temperature, the babies may take an unusually long time to hatch (if they hatch) and will usually be thin, undernourished, and will often fare very poorly.  If you sexed the safe temperatures, you risk deformities (if they hatch) or death.

The eggs are also tolerant of a relatively wide range of humidity.  As long as the incubating medium or substrate is noticeably moist, the eggs should be OK.  You can find all sorts of research about measuring the amount of moisture needed by snake eggs.    The nice thing is that a wide range of humidity levels will work.  If the substrate your eggs are sitting in/on feels moist to you, as long as there isn't any visible liquid in contact with the eggs, it will probably work fine.  Without any moisture, the eggs will dry up and die; with too much, they will either drown (such as when laid in the water bowl) or absorb so much liquid that they rupture.

Proper ventilation is easily controlled as well.  As long as there is some air exchange, the eggs will live.  Avoid placing large clutches of eggs in the bottom of a deep container or jar.  As a result of the respiration of the developing embryos, carbon dioxide, in a container allowing no or little air flow, can build up to where it covers the eggs and the clutch will smother.  A decaying incubating medium can also produce harmful gases.  This is one cause for eggs that go near full term to fail to hatch even though there are fully developed young inside.

Put the eggs on top of 3/4" of moistened vermiculite in the bottom of a plastic container (such as butter or cottage cheese containers).  If the eggs are freshly laid and moist, you can gently pull a few apart so they fit better in the container, but if they are stuck leave them as a clump.  Do not cover the eggs with vermiculite.    Place this container and 5-7 more egg containers inside a plastic storage box (sweater box) with ventilation holes around the middle of the sides.  Add about 1/2 to 3/4 of an inch of water to the bottom of the box with the egg containers.  Put the storage box lid on and incubate at 82F.  Record the date of laying and the number of eggs laid.

This incubating system works very well.  The eggs will remain relatively dry, but water will be evaporating all around them.  The water will also maintain the preferred incubating temperature so that there will be no drastic temperature changes.    Every time the lid or door is opened, fresh air will be allowed in.  To keep a constant temperature there are inexpensive commercial incubators available, or a simple one can be made with an aquarium or polystyrene foam ice chest and an aquarium heater.   Some snake rooms or cages will maintain the proper temperature ranges.   Some gradual temperature changes will not hurt the eggs.

As simple as it sounds, this is the part over which we have the least control.  If you set up the eggs properly and two weeks later the eggs still look good, most of those should hatch.  If they mold, discolor, or start sweating, they were probably destined to die, and there isn't a darned thing we can do about it.

There are times when a clutch of eggs incubates for over two months, then hatches, except for one or two eggs that have died and completely rotted away.  These eggs are usually in the center of the clutch and could not be safely removed.  As a rule, don't be too worried about removing bad eggs during incubation.  If they smell, sweat, discolor, and you can easily pull or separate them, then, by all means, do so.    The incubator will smell better and it will help keep the air from going "stale." However, be careful not to ruin a good neighboring egg by rupturing its shell while trying to pry out a bad egg.  Try to leave the eggs in the basic position they are found, relative to the top and bottom of the eggs.

If you are unfortunate enough to have those nasty little humpbacked carrion flies attack your bad eggs, you will need to take action.  If allowed to lay numerous eggs and to multiply in your incubator, they can and will kill good eggs, particularly those attached to bad ones.  If present, you may have to actually wash the clutch in lukewarm fresh water.  Use a soft brush to remove fly eggs, and change the egg substrate to rid yourself of these flies.

When there are several clutches incubating, it is a good idea to stack the incubating boxes in sequence so the box containing the oldest eggs is always on the top.  There it will be easier to watch for unexpected hatchlings.  When a clutch is expected to hatch, the container with the clutch can be taken out of the plastic storage box and transferred into a smaller plastic shoe box.  A very small amount of water should be added to the floor of the box and it should then be placed elsewhere in the incubator.    This will allow you to keep exact records of how many snakes will have hatched in a given clutch (container) without the danger of them getting mixed up with others hatching at the same time inside the larger plastic storage box.

Like most snakes, milk snakes, following slitting of the egg shell, do not immediately emerge from the egg.  Under no circumstance should you prematurely force a baby out of the egg.  If it has slit the egg, let it stay in the egg for several days if it wants to.  If forced out, a baby snake may rupture small blood vessels that are not ready to be separated from the egg remains, and bleed to death.  If most eggs are slit (baby snakes cut the shell with their egg tooth) and a day or two later there are eggs that haven't slit, carefully slit the high point of the egg with cuticle scissors.    Cut a 1" long slit, then a 1/4" cross cut at right angles to the center of the long cut, to be sure the baby can squeeze out.  You don't want to loose a baby just because it lost an egg tooth or the shell is a little too thick.

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