Professional Herpetoculture for the Pet Trade

How To Breed Cornsnakes

Breeding Cornsnakes

One of the questions we get asked quite often is "How do I breed my Cornsnake". This article will explain how we do it, using methods we've developed at VMS over the last twenty-plus years. Some articles may differ from the methodology presented here, and some may view it as overly simplified. Remember, Cornsnakes have been breeding in the wild for thousands of years without our help - they'll do it just fine in our cages, no need to make it harder than it is!

The article here focuses on raising hatchling cornsnakes, but apply equally well to many other colubrid species as well, such as kingsnakes, milksnakes, ratsnakes, etc. Remember, it's the concepts presented here that matter; the details can be varied a bit based on specie.

Do you really want to breed your Cornsnake?

This seemingly simple question is often never considered by the novice. There are several reasons to consider NOT breeding your Cornsnakes!

First, do you have a market for the offspring once they have been produced? Cornsnakes can be very prolific. If you don't have a place to sell them, you can quickly tire of feeding all those little mouths and then cleaning up after all those little...well you get the idea.

Second, do you have adequate food supplies and caging for the offspring? A typical Cornsnake clutch of fifteen hatchlings will consume around thirty newborn mice per week. That's a lot of mice. So many in fact, that local pet shops frequently begin experiencing mouse 'shortages' caused by the increased demand during peak months.

Third, are you willing to risk the life of your Cornsnake? Breeding Cornsnakes is not without risks. On very rare occasions, one snake may actually simply eat the other on introduction. Dystocia (commonly known as egg-binding) is fairly common and poses serious health risks that may require expensive veterinary services. More common is the incredible drain on body resources that egg production places on the female. If not in perfect health, a female can become severely weakened and may succumb to renal failure or disease. Speaking of disease, the simple act of introducing the two snakes together opens the door for pathogen transfer. It is not uncommon for snakes to carry substantial parasite and bacteria loads and appear perfectly healthy, even for years. Introducing such a snake to another may transfer pathogens the second snake is unable to combat; it may then sicken and die.

I'm not trying to tell you not to breed your Cornsnakes, just making sure you are aware of a few of the problems associated with it. If you still want to breed them, read on!

The Calender of Events

I'll try to present all of this information in the order it occurs, following the calendar, to enable the reader to grasp the entire cycle of events. Breeding Cornsnakes is not simply something you just do one day, it is an event which consumes an entire year. Cornsnakes spend their entire lives in the wild preparing for this one annual event - you should spend just as much time on it as they do! Please remember that these dates are not set in stone, variations in cage temperatures and other conditions may cause your results to vary. However, the overall sequence of events will remain unaltered.

January

Our Cornsnakes are hibernating now (more properly termed brumating), having been placed there at the beginning of December, in preparation for next summer's breeding season. While it seems that very little is actually happening at this time, the careful observer will note that the snakes are still active, at least a little. They still crawl about a bit, often drinking water and some will even shed their skins during this time.

Pay careful attention to them during this time. Most areas have much drier climates during the winter months and dehydration can be a problem. Make sure they have clean drinking water available at all times and check for 'dry shed' often. Many times, the snakes can be seen soaking in the water bowls when the climate is too dry - it's too cold for that! Take them out of the water ad show them to their hide boxes.

We maintain our colonies at a temperature of 50-55 degrees Fahrenheit throughout the brumation period. We also greatly reduce the amount of light available to them. While not completely dark, there are no bright light sources at all. We maintain these cold temperatures by utilizing a thermostat which controls exhaust fans mounted in the ceiling. When activated, these fans remove warm air near the ceiling and cooler air from outside is simultaneously sucked into the room via air intake ducts. Temperatures are checked several times daily and the thermostat is adjusted adjusted slightly until the room is fully cooled, at which time the temperature is surprisingly stabale. It is also recommended that air circulation be provided by using a fan. You would be surprised at how warm one end of the room can be while the other gets too cold!

For most keepers, this sort of system is impractical. We used to maintain these cold temperatures and light conditions by opening an outside window slightly, and covering the window completely with a dark sheet. Temperatures are checked several times daily and adjusted by opening or closing the window slightly. This served us well for many years!

February

Still chillin'. While this brumation all seems boring, it provides a bit of rest to the breeder, and more importantly to the snakes. Remember that egg follicles are developing and spermatogenesis is occurring in the males as well. It's important to maintain good conditions during this time so that all goes smoothly or infertile eggs will surely be the result. We also use this time to select which males will be placed with which females to produce the desired offspring. While some will breed earlier, we prefer to breed males beginning at age two, and females at age three.

March

Oh boy, now the work starts! We usually warm our snakes back up at the beginning of March. While many breeders advocate doing this by gradually warming them over a period of a couple weeks, we now know this is unnecessary. Instead we simply kick on the lights and turn back on the heat. Usually it takes a day or two to get all warmed back up. We believe, as do others, that maintaining snakes at those in-between temperatures can allow bacteria and other diseases which have lain dormant to activate and begin reproducing while the snakes immune systems are too cool to do anything about it.

We immediately check each specimen for any signs of disease and verify that they are strong enough and well-conditioned for breeding. We feed heavily during this time, after allowing the snakes a week to warm up to the idea. We find it best to feed small meals at first, gradually increasing to full-sized meals by the end of March.

Usually, the males will all shed their skins around the end of March, although this varies a bit. Make a note of this, as it serves to signify he is ready for breeding.

April

We are now feeding very heavily, and our work load is becoming tremendous, with hundreds of hungry mouths to feed and even more cage cleaning to do. Averaging two weeks later than the males, all of the females will now shed their skins, almost en masse, something that amazes me every year. It's as if the brumation period has served to reset every snakes' internal clock. It's absolutely critical to take note of this shedding, as it is the marker for the beginning of introductions for breeding. Many males will be seen to be restless, wandering around the cages endlessly - they can smell all those freshly shed females nearby!

Figure 1: a pair of courting Cornsnakes

Once the female has shed, we begin introducing her to the males' cage. You can do it the other way around, doesn't seem to matter, we just like to do it this way. If all is well, the male will show interest immediately, often pausing to smell the female as she glides by. Once he has determined that she is full of developing eggs, his interest will quickly grow and he will begin chasing the female about the cage. Things can get a little wild here, and we recommend removing the water bowl lest it be overturned. More mature snakes seem to do less chasing and often simply get right to 'business'. Here's a typical courtship scene at left (Fig. 1), with the male (a Butter) trying to position himself on top of the female (a Caramel). You can see he is trying to get her to lift her tail section a bit by forcing his tail under hers.

Figure 2: a pair of copulating Cornsnakes

If all goes well with this attempt, a closer look will reveal a successful copulation in progress (Fig. 2). Here you can clearly see that this pair knows what they are doing and soon I'll be the proud daddy of a clutch of Caramel and Butter corns (the female is heterozygous for Butter)

We'll continue introducing the pair together for periods of a day or two at least twice per week, until the female becomes visibly gravid.

May

Many pairs are still being introduced, but most females are starting to show eggs at this time. Many will lay their eggs in the last two weeks of May, although a few will not lay until June. Determining whether a snake is gravid (carrying eggs) can be difficult, but here's a few tricks:

Figure 3: a gravid Crimson Cornsnake

The first clue is a general heaviness throughout the lower half of the snake. Often, this is most visible from above and many females begin to show a 'peaked' look along the spine. This is due to body fat reserves and muscle mass along the sides being used up to produce eggs, which ride lower in the body cavity.

At left (Fig. 3) you can see a gravid Crimson corn.

Note the peaked look of the body below the curve, and the swelled area beginning somewhere just above the vent.

Figure 4: a gravid Crimson Cornsnake

Lifting the snake gently off the ground should make the swelled area beginning just above the vent even more apparent.

On lighter colored snakes, you can even see the white coloration of the eggs through the body wall. It is barely apparent in this Crimson Corn (Fig. 4), but I've showed you where to look!

Figure 5: a gravid Crimson Cornsnake

Also easily seen are the now protruding ventral scales. Normally, these are flat across the bottom of the snake, but when gravid they 'round out' in the area of the egg mass and begin to protrude, giving a rounded belly look.

You can see it at left (Fig. 5) in the same Crimson corn.

Once we see the snake is gravid, we cease introducing the male to her and await the females' next shedding. This second shed of the year is our indicator that she is near to laying eggs, usually in a week to ten days. Often, the female will become restless, as if searching for a place to lay her eggs.

Figure 6: a Fire Corn resting in her egg-laying site

Well, she is - so give her one! We use half-gallon and one gallon sherbet containers (Sean eats the stuff) which are filled half way with damp sphagnum moss. We cut an access hole in the side, near the top about twice the diameter of the snake. The last few days before laying, they rarely venture out of the cup and most will have stopped feeding. If you decide to feed a female between the last shed and egg-laying, offer only very small meals. Here's a gravid Albino Bloodred corn resting in her cup (Fig. 6).

Note that we place the water bowl nearby. Often the snakes can be seen resting with only the neck and head exposed, and having a handy drink seems like a good idea. Try not to add too much water to the moss. It should be only lightly dampened, see how it is nice and light in color. Moss that is too wet will quickly turn a very dark blackish brown in color.

June

If all has gone well, you should one day open the egg-laying cup and see something like this Crimson Corn resting with her newly laid clutch below (Fig. 7)

Figure 7: a Crimson Corn resting resting with her newly laid clutch

Most of our corns have laid eggs by now, although there may still be a few 'gravid ones' around. Within a day or two after laying, most females will resume feeding. Again, offer very small meals, increasing the size and frequency until your female is feeding normally again. She should regain body weight quickly, and will usually shed her skin about two weeks after laying.

This is the signal for reintroduction to the male if you wish to attempt a second clutch from her for the year. This is dangerous stuff, and we do not recommend it for beginners. The ability to judge the females' body weight and condition requires a few years practice. Definitely avoid it with young, small, or first year females! Producing one clutch is hard enough on your female - don't push it!

Remove the female and eggs, trying to keep them more or less right side up. It may help to have an extra set of hands, as many females do not want to be pried away from the egg mass. I've never had one bite, but they can sure hang on sometimes! Now place your eggs in the incubator (which hopefully is already set up) and wait.

Much has been written about incubation, too much in fact. In truth, a healthy clutch will hatch in just about anything other than the glove compartment of your car. The only requirements are that humidity be held rather high and that temperatures stay within reason.

Figure 8: a fine clutch of Cornsnake eggs set up for incubation

We hatch most of our Cornsnakes at 78-80 degrees, but it can vary a bit. I've seen eggs hatch anywhere from 72 to over 90 degrees with no ill effects. Stable temperatures are not as important as most breeders believe. In fact, recent research indicates that some variation in temperature may actually produce a more even sex ratio in the hatchlings and produce larger, stronger hatchlings.

We use plain old vermiculite as a media, mixed with water. It is available at garden centers. You do not need to get crazy over how much water! I've seen a gazillion ratios by weight and volume - ignore it all. Just add water until the vermiculite will pack into a 'snowball' and when squeezed very hard will not yield more than a drop or two of water. We place the eggs in clear plastic shoeboxes or sometimes in tupperware type containers, without ventilation holes of any kind. We simply open the containers for air exchange once a week as we check for any dead or rotting eggs. A healthy clutch of eggs set up properly should look something like the one illustrated here (Fig. 8)

Notice all of the eggs in Fig. 8 are clean and white, the eggs are very full and smoothly rounded, and that they adhere in a clump. Eggs that are infertile will appear yellowish and often have a wet feel to them, not dry like the clutch you see here. Often, infertile eggs will not adhere in clumps. If you are not sure, set them up for incubation anyway and discard them as they begin to mold. Try to separate them from any good eggs, to prevent the mold from spreading. Usually, infertile eggs can be pulled from a clutch without much trouble - for some reason they seem less adherent than healthy eggs. Never try to separate healthy eggs, they will almost always tear. Stubborn infertiles can often be 'sawed' away using waxed dental floss, an idea we got from Dave and Tracy Barker of VPI.

Figure 9: an infertile egg is at lower right

Many breeders state that you do not need to remove bad eggs, usually saying something along the lines of "good eggs have a natural fungus inhibitor and it is not necessary". While good eggs do have a certain natural immunity, bad eggs still smell and certainly foul the air the good eggs are 'breathing'. I have seen certain types of fungus develop and kill entire clutches, so why not just remove them?

Shown at left (Fig. 9) a clutch of eggs (from a Mandarin Ratsnake), note the infertile egg at lower right.

July

Eggs are starting to hatch out now, second clutches are being laid and our workload is astonishing! Some snakes will produce second clutches as late as August, it all depends upon environmental conditions. Notice that early in the season, all of the snakes were 'synchronized' following brumation, but they are now beginning to show some variation in schedule. This is easy to see with a large collection, such as we maintain. For example, a series of racks containing 90 Cornsnakes located on our south wall will consistently produce eggs in series, starting at the top and moving steadily downward over the course of a few weeks. This is caused simply by the variation in temperatures within this room - it tends to be warmer up high and cooler lower to the ground! So if your snakes are beginning to 'fall off' the schedule presented here, don't worry - it is just that your conditions are slightly different.

Figure 10: a clutch of Cornsnakes is 'pipping'

If all has gone well, you should look in your incubator one day soon and see this (Fig. 10):

Within a few days, you'll have a fine batch of little Cornsnakes on hand. Resist the urge to forcibly remove babies from the egg, they'll exit when ready and remember that they are very delicate at this size.

We simply place the entire batch of hatchlings into a single baby box. We'll lightly mist them each morning, since it's so dry here in Colorado. Some breeders simply leave them in the incubation container until they shed their first skins. But I like to remove them for observation and to record data from the breeding for genetic records.

After a few days, they'll shed their first skins. Then they will be bright, shiny, utterly adorable, and ready for their first meals. We'll feed and separate each one into it's own little cage, as described in our 'Raising Baby Snakes' web page.

August

While a few of our corns will still be laying second clutches, most are finished for the year and this is the real beginning of what I call 'the fattening'. For this entire month, and the next two as well, female Cornsnakes will consume an astonishing amount of food. While our males will be on a maintenance diet of perhaps one feeding every other week, the females will be getting a small meal every two to three days! They've earned it, as many have produced thirty or more eggs for us.

If your snake has finished earlier in the year, by all means start fattening her up earlier - don't wait!

September

More feeding, more cleaning, although many females will have already regained a nice plump appearance. It always amazes me how fast this can happen - provided the female was not severely stressed by overproduction. Those that are not regaining weight well, are marked and carefully observed for any problems which may require veterinary attention.

October

More feeding, more cleaning, although most females will have been returned to normal weekly feeding schedule. Those that are not regaining weight well, are marked and unless a sudden change for the better occurs, will not be bred the following season.

November

Now we are preparing for the upcoming return to brumation - and looking forward to a little rest! I'm sure the snakes are looking forward to it too! We feed all of them, male and female alike, heavily for the first two weeks of November, and then cease all feeding for the last two weeks. This allows time for the snakes to fully digest all meals, clearing out their digestive tracts before entering brumation. Snakes with digestive tracts containing undigested food will certainly encounter health problems if cooled.

December

All of our Cornsnakes are returned to winter brumation conditions sometime during the first week of December. Pay careful attention to them during the first few weeks. It often takes a day or two for the room to cool, and prowling specimens may tip over water bowls or spend excessive amounts of time soaking in the water dish. Snakes which soak excessively or are kept damp at this time have an increased potential for health problems. We usually remove the water dish and provide a very secure hiding place for such snakes. Once they've found the hiding place to their liking, the water dish may be returned to the cage.

Now that the snakes are all cooled down, we can take a break, look around at the scenery, and maybe even get caught up on all those unfinished projects around the house. Now that I stop to listen, Christmas songs are playing on the radio! I better get out and get some presents for friends and family - I know my Cornsnakes will give me more presents next summer!