Feeding Your Reptiles: Frozen/Thawed Rats and Mice

One of the first questions that comes up whenever I tell people that I have pet snakes is inevitably, “what do you feed them?”  People are incredibly curious about how snakes eat, what they eat, and where you get such things.  And many people reveal during these conversations that the only reason they’d never looked seriously into getting a snake as a pet was because of a fear of (or simple distaste for) the idea of feeding live prey.

Most people are a bit surprised when I tell them that I simply buy frozen mice or rats, usually in bulk (packages of 12 or 24) so that I don’t need to worry about going to the pet store every single week.  I can then thaw the prey items out, one at a time, much like you’d thaw out a chicken breast before cooking it.  It’s fast, easy, and convenient.  And my snakes get a good meal whenever they need it, without me having to trek across town to the pet store, or worry about keeping live rodents in my apartment.

 

So Why Frozen/Thawed Instead of Live Prey?

There are people who make the argument that live prey is more “natural”, because a snake in the wild has to stalk and kill its prey.  I find such arguments to be patently ridiculous, because there’s really nothing “natural” about keeping a snake in a glass enclosure in your home.  Most snakes in the pet trade were captive-bred — they’ve spent their lives living in “unnatural” conditions — and many were selectively bred for traits that would get them killed in the wild (ie, albinism).  Snakes in the wild rarely live for more than a few years, while in captivity they can live for decades.  Perhaps a frozen/thawed mouse is a bit unnatural, but it’s certainly no more unnatural than feeding kibbles or canned food to your cat or dog.

Many shops that carry reptile products do offer live prey items as an option, but any argument that a live mouse is somehow “healthier” or contains “more nutritional value” than a frozen one is purely specious — if anything, the frozen prey will be healthier, because pet stores often don’t have very good housing conditions for their prey items, don’t properly feed them, and don’t monitor for health problems the way that a dedicated rodent production facility has to do.  Live prey items might also carry parasites picked up at the store (or elsewhere), which freezing will kill off — live prey items are a potential source of mite infestations, for example, or may contain parasites in their guts.

The biggest risk with live prey, of course, is that it might fight back.  Rodents have long, sharp teeth that can seriously injure your beloved snake-friend.  A snake that misses on the first strike, or gets a bad grip on its prey, can be severely bitten (even killed) by a cornered, fighting-for-its-life rodent.  Vet bills for reptiles get expensive quickly — since they’re an “exotic” pet, even walking in to the vet’s office or emergency clinic with them can be a $100 appointment fee, before any tests/surgeries/medicines/etc even enter the picture.  And many vets are untrained in reptile care, and will be able to do little to help your injured friend — especially if you’re going to an emergency clinic or the like.  Herpetological specialists are rare, and their offices may have limited hours.

 

What If My Snake Doesn’t Like Already-Dead Food?

There are instances where a snake doesn’t immediately take to eating things that have been pre-killed for it.  Wild-caught individuals (which you should never buy — animals taken from their natural habitats are usually illegal and have to be smuggled across borders, are typically less healthy, and you may be destroying natural ecosystems by participating in their sale), or animals who were raised on live prey in captivity (there are still some major breeders out there who feed live, despite the risks), may not immediately recognize a frozen/thawed rodent as a food item.

There’s the odd animal who will simply never take to eating frozen/thawed, especially if this type of prey was not introduced to them until they were an adult.  But in 99% of cases, a bit of care and attention will get your animal eating f/t prey.  A few tricks to try, if you’ve got a fussy eater on your hands — I’ll arrange them from least to most macabre:

• Warm the prey item to approximately body temperature by immersing it in hot water until it feels warm to the touch.
• Wiggle the prey item around in front of the snake’s face (you may want to use tongs or forceps, rather than just holding the prey item in your hand — it’s not unheard of for a snake to mistake a human hand for a yummy rat, especially if you’ve got rat-smell all over your fingers).
• Cut the prey item open a little bit, to get a stronger “blood” smell for attracting the snake.  Anecdotally, puncturing or crushing the skull is the best way to do this (apparently brains smell delicious), but if you’re squeamish it may be better to go for a less-gruesome tactic.
• Try purchasing a live prey item, but killing it just before feeding it to your snake.  I’ve seen various YouTube demonstrations of how to use vinegar & baking soda to make a CO2 chamber at home, or how to use CO2 cartridges for the same purpose, but such DIY creations tend to be unreliable — often the prey simply falls asleep, and doesn’t actually die.  And there’s an argument to be made that suffocation may not be particularly kind, even if it looks (from an outside perspective) like just falling asleep.  If you’re not terribly squeamish, snapping the spine is one of the most humane & painless ways to euthanize a rodent.  If you feel confident in your ability to do so, snapping the neck manually is the most precise and “gentle” method.  Many people teach to simply whack the rodent (hard) off a table or other hard surface, which is less precise and may only stun the prey item, not actually kill it … plus it just looks & feels fairly brutal.  My chosen method (because I hate feeling bones snapping in my hand) is to place a hard, thin object like a screwdriver over the rodent’s neck, hold the tail in my off hand and the screwdriver in my dominant hand, and push (sharply) down and forwards.  It’s fast and precise, and the prey item feels little-to-no fear or pain, because it all happens in less than a second.  I don’t like doing it, but I’m pragmatic enough to understand that this is still far less traumatic to the animal than being dropped into a tank with a live snake, and then bitten & squeezed to death, would be.  Always wear gloves when handling live rodents; they have big teeth and can deliver mean bites.

If absolutely none of the above suggestions work, and your snake has gone a long time without eating, you may have to resort to live prey.  If that’s the case, feeding smaller prey items with greater frequency is usually the way to go.  A snake that could eat a medium-sized rat twice a month, for example, might do better if fed rat pups, every single week.  Younger/smaller prey items are less likely to be able to fight back or inflict serious injuries on your snake.  Never feed live prey without supervising the feeding process (have a set of good, thick gloves on so that you can pick up a struggling rat or snake should things go badly), and be aware of risks like parasites — check incoming live prey thoroughly to be sure it’s not carrying mites or the like, and always check your snake out visually following a feeding to look for bite or scratch injuries.

 

Are There Any Risks With Frozen/Thawed?

Now that I’ve outlined how f/t is the safer and more humane way to go, I’ll go over the couple of risks that may come along with feeding frozen prey items.

Most important is making sure that the prey item is thoroughly defrosted.  Snakes are cold-blooded.  A prey item that feels warm to the touch, but still has a big chunk of frozen meat inside of it?  That could cause your snake’s internal temperature to drop enough to cause serious problems, or even death from organ failure.  The same is true if the prey becomes too warm (which is why you should NEVER use a microwave to defrost frozen prey — the internal organs of the prey item will heat much faster than the outside, and can get hot enough to cause burns).  The microwave also risks actually cooking the meat, and snakes don’t have the same biology that we do — their bodies aren’t designed to digest cooked meat.  Defrosting a frozen prey item is best done by immersing it in hot water and leaving it to sit until it’s thoroughly thawed out (the larger the prey item, the longer it needs).  Give the prey item a squeeze, to make sure there’s no big frozen parts inside.  If it still feels cold to the touch, it’s not ready yet.

The other risk (which isn’t really limited to f/t items, but is more of a concern because they’re probably being stored in your freezer alongside your own food) is transmission of any rodent-borne dirt/bacteria to your own food & utensils.  Keeping separate “snake utensils” is recommended — a set of tongs & a “defrosting bowl” that are for snake-related uses only.  Frozen rodents are unlikely to have any parasites or diseases still living on them, since most bacteria and viruses and the like can’t live at freezer temperatures, but double-bagging frozen rats/mice & being sure to wash your hands after handling is a useful “just in case” measure.  Double-bagging also helps to prevent freezer burn, and may help to disguise the bag of frozen rats from any friends/family who happen to open your freezer and peek inside (I’ve definitely had friends scream and drop glassware upon going into my freezer to grab the bottle of vodka I keep in the freezer door, because the other shelf in the freezer door is the “rat shelf” … several broken glasses later, I’ve learned to warn people of this in advance).

 

Costs and Additional Notes

Snakes are extremely low-maintenance pets.  Being cold-blooded, they only need to eat a fraction of the amount that a warm-blooded mammal or bird would — and (generally) the larger the prey they eat, the less often you need to feed them.

Here in Southern Ontario, small “pinky” or “fuzzy” mice cost about $1-$1.50 apiece, while adult mice may be $2-3.  Medium-Large rats may be more in the $5 to $8 range.  If you’ve got an especially large animal, you may need to be feeding a larger prey item like rabbits, which can cost $15-20 depending on availability in your area … but on the plus side, such larger animals often only need to eat once a month or so.  Buying in bulk can get you discounts, but you need to have freezer space for storing 24 or 50 or 100 prey items in order to make such discounts a viable option — and remember that like with all food, there’s a limited amount of time that something can be kept in the freezer before freezer burn starts to set in & nutritional value is lost.  Airtight storage bags & a clean freezer without frost on the walls will help with longevity in storage.

If you’re getting a new snake, ask the breeder/store/rescue where you’re acquiring it if it’s already eating frozen/thawed prey.  If not, be prepared that you might have to spend some time teaching your new pet to take f/t, and be ready to potentially buy some live rodents & kill them yourself, to get things started.  If that doesn’t seem like something you’re prepared for, ask for another animal that’s already taking f/t, or ask if they’d be willing to “test” the animal on f/t food for you, before you commit to buying/adopting.

And if you really love the idea of having a pet snake, but really *can’t* stomach the idea of handling dead mice/rats, there are a few species out there that eat other foods — like eggs or fish.  Dasypeltis, an African breed, is a commonly known egg-eating colubrid snake which you may be able to get your hands on (although they’re much less common than other colubrid species in the pet trade, and finding a captive-bred specimen may be challenging) — they are usually fed quail eggs in captivity.  Many species of garter snake prefer to eat fish (although live feeder-fish carry high risk of parasites; do your research before deciding on a fish-eating snake as a pet, and you may want to go frozen/thawed with fishy feeders, too, to kill off any parasites).  Other colubrid snakes may eat eggs, fish, or earthworms — but they may require vitamin or calcium supplements added to their diet, as these foods are not as nutritionally valuable as mammal prey.  Thorough research is necessary before acquiring any pet — don’t simply trust what “some guy at the pet store” said.  There are myths out there about snakes eating insectivorous diets and the like — these are MYTHS, and a snake won’t get proper nutrition eating only bugs.  But if you’ve done your research well, a non-rodent-eating snake may be a very beautiful and rewarding pet choice.

Meet the Menagerie: Hypatia and Daedalus

As regular readers will be aware, I’ve got a particular love for colubrid snakes (snakes of the family Colubridae, which includes king snakes, rat snakes, milk snakes, and many others).  To that end, I’ve expanded the menagerie recently with two new additions:  baby corn snakes, Pantherophis guttatus guttatus.  Hypatia and Daedalus.

Hypatia

Daedalus

Since corn snakes require virtually identical care to king snakes, which I’ve already covered in a previous post about Penelope, my California king, I’ll avoid repeating myself and instead focus on some of the other interesting aspects of my new little friends.  There’s also lots of reputable websites out there with excellent basic care information, and I’ll link to a few of them at the end of this post.

Colour Morphs

Now, someone not particularly familiar with snakes might look at those photos I posted up above and say, “wait, those aren’t the same type of snake!”  But looks can be deceiving, and yes, they are both corn snakes.  Corn snakes have, however, been a popular pet species for several decades, and in that time there have been many captive breeding projects aimed at producing interesting, and incredibly varied, colour morphs.  Hypatia is what is known commonly as a “butter” corn snake, while Daedalus is a “lavender”.  Neither of these are colours that you’d be likely to see in the wild.  But in captivity, there’s been a lot of success with producing a great variety of morphs, and captive-bred corn snakes are now available in almost every colour you can think of (not in blue, yet, but I’m sure there’s someone working on it as we speak).

How these different colours are produced is actually quite interesting, if a little bit complicated.  To begin with, there are several different “wild types” of corn snakes.  These are corn snakes that, because of being geographically isolated from each other, have evolved to have slightly different colours and patterns.  The Keys corn snake is a pinkish hue, and tends to have a slightly smaller adult size.  Miami corn snakes have grey or very light tan bodies, with dark orange “saddles” (the splotches on the back) outlined in black.  Okeetee corns (found on the grounds of the Okeetee hunting club in South Carolina) have bright orange bodies with dark orange or red “saddles”, and the saddles have thick, black outlines around them.  And finally, there’s the Carolina (or “normal”)  corns, which have bright orange bodies, dark orange or red “saddles”, and thin, often incomplete, black outlines around the saddles.  Any of these “wild types” will act as dominant, while other colours may be present as recessive traits, hidden invisibly in a snake’s genetics.

In the wild, with so many snakes interbreeding with one another, it would be unlikely for two snakes with the same recessive trait to meet and produce eggs.  But get snakes into captivity, and the available gene pool shrinks considerably.  Inbreeding tends to bring out recessive traits, and in captivity, that’s what happened.

So far, we know of more than a dozen different genes that can affect a corn snake’s colour and pattern.  Several produce similar effects (there are 4 different strains of hypomelanistic, or albino, corn snakes to be found, and it’s difficult to tell the difference between them just by looking; you have to know your snake’s lineage to be sure if it’s a hypo, a sunkissed, a lava, or an ultra).  Others are quite unique (the Palmetto morph, for example, is particularly striking, and certainly hard to miss).  Other genes don’t affect the snake’s colour, but change the shape of its pattern — Motley snakes have dots instead of saddles on their backs, while Stripe morphs are, well, striped.

It doesn’t just stop there, though.  Because each of these colours or patterns is produced by a different gene, you can get snakes that exhibit multiple different recessive traits at once.  Butter corn snakes, like my Hypatia, are such a combination: a butter corn must have both the “amelanistic” and “caramel” traits.  And it’s not just as simple as taking a caramel-coloured father and an amelanistic mother and breeding them together: it takes several generations to produce a line of snakes with such a combination of traits, because you have to eliminate any “normal” genes, which would dominate over the recessive traits and thus the snake would appear just like a wild-caught specimen.  Even harder is combining 3 or 4 traits — but with patience, almost any number of combinations can be achieved.  It can be a bit of a gamble for breeders, though — while combining 4 different traits could produce something never before seen in the pet trade, it won’t do you much good if the resulting snake looks boring, or too similar to something that’s more easily produced.

A Basic Corn Snake Genetics Lesson

If the above paragraph left you feeling lost, I’ll try to make it a bit more simple here.

Say a corn snake has 4 different genes that can code for 4 different colours (they have a lot more, but I’m reducing it here to make the example a lot more simple).  We’ll call those genes N (for normal, like a wild-caught snake would be), a (for amelanistic), c (for caramel), and l (for lavender).

Now, each snake would have two copies of each gene — one from their mother, and one from their father.  Because N is dominant, while the other genes are recessive, a snake needs 2 copies of the same recessive gene in order to express (show) the colour for which that gene codes.  Otherwise the dominant N would be the thing that ends up showing.

In this example, Daedalus (my lavendar corn snake) would have two l genes coding for lavender, but only N genes in the places that might code for caramel or amelanistic.  So a chart of his genetics would look like:

amelanistic    NN

caramel           NN

lavender          l l

Hypatia, on the other hand, would have double-recessive genes for both amelanistic and caramel — but since she doesn’t express a lavender trait, she’d have N genes there:

amelanistic    a a

caramel           c c

lavender          NN

Now we’re going to complicate matters.  If Hypatia and Daedalus were to have babies together, their babies would all look like normal, wild-caught corn snakes, because each one would receive one recessive trait from one parent, and one dominant trait from the other.  The dominant Ns would be what showed up — but all of the babies would be what is called “heterozygous” for all 3 traits, since they’d have the recessive traits still hidden, unexpressed, in their genetic codes.

__________from Dad      from Mom

amelanistic    N                          a

caramel           N                          c

lavender          l                           N

But if we were to breed those babies together with each other, that’s where it gets really interesting, because now there are many options for what each parent could contribute to the genetic mix.  This website is great for calculating the odds of what you’ll get from parents with known genetics, and from that we can see that there’s a 1 in 64 chance that you’d get a baby with all 3 traits expressed: caramel, lavender, and amelanistic together.  The vast majority of the babies (27/64) would be just like their parents — normal in appearance, but with hidden genetics lying unexpressed beneath the surface.  Some would have one, or even two of the traits expressed, giving you some amelanistic babies (9/64), some caramel (9/64), some lavender (9/64), some butter (3/64), some caramel/lavender combos (3/64), and some opal — a combination of amelanistic and lavender — (3/64).

This is, essentially, the same way that human genetics work.  Just like blonde hair and blue eyes are recessive and may be “hidden” by dark hair and eyes, so may various corn snake colour traits remain hidden for many generations, until a limited gene pool (or sometimes just random chance) brings them out.

Less Complicated Things

All right, so that was still rather complicated.  Genetics are kind of weird, although once you get the hang of it, they’re very much predictable.  But let’s move on to some of the less complicated reasons why corn snakes are so interesting.

Corn snakes are fairly common in the wild, being found all across the southern U.S. and down into northern Mexico.  They live in a huge variety of habitats, from the arid climate of Texas to the damp woodlands of Florida, from sea level to as high as 6000 feet in elevation.  In cooler areas they will hibernate through the winter, but in more temperate climes they’ll simply go into a period of reduced activity between December and March, spending more of their time hiding in rock crevices and less out hunting and basking in the sun.  This winter cooling, or “brumation”, is actually a necessary part of their breeding process — without a brumation period, snakes won’t readily breed in captivity.

Like most snakes and other reptiles, corn snakes do not care for their young the way that mammals and birds do.  After laying her eggs in a warm, moist location, the female corn snake goes away to resume her normal life.  The eggs are left to incubate by themselves (not a problem, since they incubate safely at a wide range of temperatures, anywhere between 72 and 90 degrees, which in their habitat is a relatively normal summer temperature).  Depending on temperature, the eggs will take 50-60 days to fully develop.  The baby snakes that hatch out are completely independent, ready to go out hunting almost immediately for their very first meal.

In the wild, corn snakes are sometimes mistaken for venomous snakes such as copperheads and killed by ignorant humans.  But these shy little snakes can be a great help in keeping down the numbers of pest species such as rats and mice, and so they should be encouraged to live in your yard if you happen to be in an area where they are native (plus it’s just nice to have cute little snakes in your yard!)  Corn snakes, while not endangered, are at risk from habitat destruction, and so by creating a place that is safe for them, you are protecting your local biodiversity.

While corn snakes usually like to stay on the ground, they are excellent climbers.  In the wild they may climb up trees to get at bird eggs or other delicacies, while in captivity they will explore every inch of their tank and may even amaze and baffle you by climbing up the bare glass, like Hypatia is in this picture:

They are also incredibly good at finding absolutely any hole or gap in their enclosure through which they might escape, and so it’s very important, if you want to have a corn snake as a pet, to buy a tank that is specifically designed for keeping snakes, and to check it carefully for any little gaps and spaces (note the bit of duct tape on Hypatia’s tank in the photo above — that’s covering up a tiny space where the lid clips on to the tank).  Corn snake escapes are unfortunately rather common, and they can be hard to find again once they do get out.  Protect your baby (and show courtesy as a pet owner) by making sure they can’t pull a Houdini on you.

More Information

Care sheet and basic information

Another care sheet

Pictures of hundreds of different colour morphs

TheCornSnake.co.uk (information, links, and forums)

Corn Snake Calculator (figure out what morphs you’ll get by breeding your snakes)