A FIELD OF OPPORTUNITY

Going back to nature with corn snakes.

Corn snakes belong to the Colubridae family. Formerly this species was considered synonymous with the Elaphe genus. Now, the term ‘Elaphe’ loosely represents several genera, most of which are commonly called rat snakes. Being closely related to the rat snakes of North America, corn snakes are medium-sized constrictors that are adaptable by nature and widespread across Eastern and Central USA. However, the corn snake with its distinctive name and iconic patterns became a symbolic icon of the exotic pet boom in the 1980s. Today, they remain the most popular pet snake in the world due to their docile characteristics and reliable availability across the planet. They are a flagship species to inspire young people to engage with herpetology and have changed the perceptions of Ophidiophobes for generations. However, the natural history and wild conditions that corn snakes thrive in are rarely the focal points of these interactions, meaning there is a lot more that mother nature can teach us about our much-loved corn snake.

Corn snake diets

The name ‘corn snake’ is thought to come from the patterns on the underside of this species’ belly, which looks like the flecked pattern on maize (or as it is referred to in America; flint corn). However, it is true that, like many rat snakes, corn snakes are found near corn due to their fondness for a rodent diet. However, these constrictors feed on a variety of prey in the wild.

In 2016, Researcher Brett Degregorio (et al) at the Arkansas Cooperative Fish and Wildlife Research Unit studied the ‘nest raiding’ behaviour of corn snakes. He video recorded 97 nest sites and discovered that “of the four snake species documented preying on nests at our site, Corn snakes were the only exclusively nocturnal nest predator, arriving at nests between 20:24 and 02:20. Corn snakes were nearly five times more likely to prey on nestlings than eggs, suggesting that they may locate nests visually during the day. On four occasions, corn snakes arrived at nests shortly after or while other snakes preyed on nestlings, indicating that corn snakes may use cues provided by other snakes to locate prey.”

This is only a snapshot of the species’ natural diet which only occurs during nesting season, so chicks should only be provided infrequently during spring. Keepers who are building a first, or new enclosure should consider installing a cork bark tube in an elevated position which they can utilise as a nest-feeding platform in the future. Throughout the rest of the year, rodents make up the bulk of the corn snake’s wild diet. Youngsters will regularly feed on amphibians and small lizards too. Appropriately sized rodents are therefore the best option as a ’staple’ diet, but ‘snake sausages’ were once popular and experimentation with shop-bought frogs’ legs and quail eggs can help vary the diet (although they should only be provided every 6 months as a treat).

Enclosure and environment

Over time, our perception of what makes an ideal corn snake enclosure has changed. From heat mats replaced with overhead heating and lignocel replaced with bioactive substrates, the provision of naturalistic vivaria is becoming much more commonplace. However, one area that is hotly contested is the arboreality of corn snakes. We know from diet analysis that corn snakes will venture reasonably high off the ground to feed on bird nests, but is it fundamental to their development?

In a paper published in the Journal of Zoo and Aquarium Research, Paul Rose at the University of Exeter and Steve Nash at Sparsholt College compared behaviours of two populations of juvenile corn snakes, one in a naturalistic enclosure, another in a basic set-up. Paul writes: “Corn snakes are classed as rat snakes, a group of snakes known to be highly exploratory, preferring a heterogeneous habitat of natural and man-made environments. These exploratory traits should be encouraged in captive enclosures.”

“Comparison of the two populations highlighted the effect that extra furnishings have on the location of snakes in their enclosure; those in an enriched exhibit spent 31.7% of their time exposed and on view, whereas limited furnishings caused the snakes to be hidden for 98.6% of the total time observed. Snakes in the non-enriched exhibit, whilst provided with limited climbing opportunities, still did not use this element of their environment; yet an increase in the availability of climbing “material” showed that the snakes spent 64.3% [of their time] off the ground.”

Whilst we know that environmental enrichment is key to successful husbandry, creating a true biotope for a corn snake may prove difficult. As an adaptable species, the corn snake can be found across a variety of habitats from rocky outcrops to wetlands and urban environments to pine forests. With New Jersey (at the Northernmost of its range) dropping below 0°C in winter and Florida (at the Southernmost tip) reaching upwards of 38°C in summer, this is a versatile species. This has given the corn snake a grasp of the Caribbean, where it is considered a widespread invasive species. Whilst this versatility makes for an undeniably hardy snake, it presents challenges to keepers looking to replicate the exact wild conditions of the species as this will vary across localities.

Keepers should be aiming for a happy medium, but still providing all the core components of good husbandry such as a full light spectrum and deep-penetrating overhead heat. This can best be achieved by combining a Zone 1 T5 or T8 tube with an incandescent spot bulb. The basking spot should reach a comfortable 32°C. The ambient temperature should be around 26°C, dropping slightly lower in the ‘cool end’. Night temperatures should drop as low as 20°C and experienced keepers can provide some seasonality by dropping ambient temperatures even further through the winter. In Tallahassee, Florida in the heart of their range, summer provides around 13 hours of daylight while winter is around 11. Programming a thermostat to turn the spot bulb on for one hour before the UVB source will mimic sunrise (and vice versa for sunset). In Florida, humidity averages around 90% in the morning, but drops to around 50% in the afternoon. This is consistent throughout the year but has the greatest contrast during the summer months (94% morning, 55% afternoon). Therefore, keepers should aim for a steady 60% humidity. Spraying the enclosure at night will keep a high humidity, which will eventually dry out through the following day.

Keepers should also be providing their adult snakes with as much room as they can accommodate. Whilst young snakes may benefit from a smaller, secure enclosure, adults that are feeding readily will appreciate the opportunity to stretch out. As a docile species that tolerates handling well, keepers can create entire rooms full of enrichment opportunities, such as cardboard boxes, tubes, packing peanuts, climbing frames and much more. Sandpits full of different substrates, or fresh water can help maximise the enrichment available to a pet snake. As a crepuscular species, it is best for keepers to accommodate this during the evening hours when the snake is most active. Providing enrichment should be a rewarding process for both the snake and the keeper and can encompass a whole spectrum of activities to stimulate the cognitive, physical, and sensory abilities of the animal.

Captivity vs the wild

Whilst we should be looking towards the wild to replicate the most ideal conditions for our animals, sometimes that can be difficult when a species has been bred in captivity for such a long time.

Stephen Sharp had been keeping reptiles since 1971 and began breeding corn snakes in the early 1980s. As someone who has observed the rise in popularity for this species and is responsible for producing the great grandparents of some of the snakes in captivity today, as well as pioneering early experimental use of UV in herpetoculture in the UK, he has seen corn snake keeping blossom over the decades. He told Exotics Keeper Magazine: “Across the corn snakes’ range, there are lots of distinct locality populations, but many of the ones we have in captivity today are cross-bred to some extent, of these locality populations. It would be interesting to do some genetic analysis of the corns that exist in the hobby today. There was so much hybridisation back in the 1970s and 80s in the UK that I would say many “corns” back then had some rat snake in them. Certain genes are accepted as “corn snakes” today, despite the fact they were produced through hybridisation. Some are more obvious such as ‘ultra’ which is said to originate from the grey rat snake (P. spiloides).

“It is nothing new, cross-breeding certainly happens in the wild, where corn snakes share their distribution with other rat snakes, but this happens much more frequently in captivity. In the 1970s there just wasn’t dedicated reptile shops so a handful of snakes, imported from the US would be housed together in a pet shop. In the case of corns and rats there was the possibility of hybridisation. In the case of kingsnakes, it would be much worse!”

“Because these were the earliest snakes to enter the hobby, there was a lot of contamination in locality bloodlines. At the time people didn’t realise, it wasn’t until the early 90s that the hobby tried to create a genetic database for the corn snakes in captivity. There were two databases, one in the US and one here, but neither of them had a strict confirmation process. So, people would register their animals without absolute certainty of their genetics, which defeated the point of the database.”

A Field of Opportunity

Variation in morphs

There are (at the time of writing) 849 recognised corn snake morphs and the number continues to grow. Some of the earliest colour mutations are from wildtypes that were selectively bred in the 1980s. The ‘Okeetee’ was first produced by Kathy Love from a locality found in Jasper County, South Carolina. With bold, distinctive saddle markings, this stunning colouration was one of the very first recognised morphs. Other wild types include the ‘Alabama’ which has darker colouration, the ‘keys’ which has lighter colouration and the ‘Miami’ which displays a lot of grey pigment. From here, the endless possibilities of morph breeding began.

For the most part, the variation between these animals is entirely morphological. However, some morphs do have slightly different care requirements and can be prone to genetic conditions.

Stephen explains: “For me, the reason corns became so popular was simply the isolation of genes which produced different colour morphs. Producing morphs became the lifeblood of the hobby. Amel was the first gene in corn production. It reduces black creating a bright red/orange/yellow corn. Other early genes are Anery, which reduces red and created a black/brown/silver corn. Caramel produces a straw colour morph. Lavender produces a “mocca” colour corn. Hypo reduces black and produces a much brighter coloured snake. By mixing and matching these genes, and others, the vast array of colour morphs we know and love today were created.”

“In my opinion, wouldn’t use UV for an Amel corn snake. Amelanistic means they lack the black pigment that helps protect them from UV burns. You can tell when an Amel has been exposed to high UV as the sheds will come off much thicker, which is skin damage.”

“There are also some morphs which are known to have potential issues. For example, “sunkissed” corns can suffer from a head wobble called ‘stargazing’. It is thought sunkissed may have originated as a localised hybrid population involving corns and king snakes possibly 1000’s of years ago. Stargazing became a problem in some captive-bred sunkissed lines via selective breeding.”

“It is also common for Lavenders to suffer from spinal kinks. One line of Palmettos had some Texas rat snake (Pantherophis obsoletus lindheimeri) blood in them, which caused some to suffer from ‘bug eye’. There are lots of perfectly healthy ones now, but one line did have issues.”

Now we understand the importance of genetics much better, breeders are better able to network with one another to produce healthier offspring from varied bloodlines. With a large number of snakes being produced in breeding facilities, some breeders are currently operating digitalised databases to track the genetics of each individual animal. This responsible approach means that problematic genes are controlled much better now.

The process of breeding

Many of the most popular species today reached their position in the hobby due to their hardy characteristics, docile personalities, and willingness to breed. Refining the process to breed corn snakes in the 1980s is why now, even with exotics keeping rising in popularity, “corns” are readily available throughout the year.

“Breeding corn snakes is quite straight forward” explained Stephen “Males reach sexual maturity from around two years old whereas females are closer to three. If the snakes are younger than five years old, they shouldn’t have any problems breeding once they’re paired up. After this, they require a cooling process to encourage better sperm count. Then, around two months after pairing, the female should lay a clutch of eggs and two months after that there should be hatchlings.”

The pairing of animals generally happens around February/March. Like most species, corn snakes benefit from the replication of the seasons to prompt breeding. Whilst it is not entirely necessary to provide environmental fluctuations, it does generally provide more successful reproduction.

Stephen continued: “Many breeders will males and allows the breeder to keep track of when the female sheds and begins producing pheromones.”

Once the female sheds post-brumation, she should begin producing pheromones and the two adult corns can be paired up. Females are usually introduced to the male’s enclosure, so they can be tracked and paired with multiple partners in a season. Once the eggs are laid, they must be incubated for approximately two months before they hatch. Stephen continued: “These should then hatch between six and a half and 12 weeks. After 12 weeks, it is unlikely the egg will be successful and the more time that goes on, the less successful a clutch will be. Interestingly though, the animals that do survive after being incubated longer tend to be bigger and more robust.”

Most breeders will keep hatchlings for at least 3 weeks to ensure they are feeding. Commercial breeders may choose to hold onto their animals a little longer to do thorough health checks.

In the early days

Stephen began his hobby during some of the earliest days of herpetoculture. As a newly emerging discipline, there were few (if any) dedicated products and light. All lighting and thermostats came from the tropical fish hobby.”

“I was one of the first reptile keepers to import UV lights (Black lights and then later Tru-Lite) into the UK. I had read a book that linked UV and improved D3 production. I obtained these for use with lizards initially and years later, decided to try them with some Western fox snakes (Pantherophis vulpinus) had that were notoriously bad breeders. Once we introduced UV, they were excellent and bred for 12 years. In fact, I would guess most fox snakes in the UK hobby today come from that pair. I also found a lot of success with Macklots pythons (Liasis mackloti) at that time because of the UV. Blood pythons under UV became aggressive, which is much more like their wild counterparts. They would be aggressive and much more active for several hours after turning the light off. This led me to supply Black Lights to several zoos and private keepers.”

“This wasn’t all great though and UV wasn’t without its problems. I had worked with the Ministry of Agriculture, Fisheries and Food (MAFF) before it was DEFRA and they had reports of ‘hard scale back’ particularly in Bosc monitor lizards (Varanus exanthematicus) which were common pets at the time. These were reactions to the high-intensity UV bulbs, that were

Herpetoculture is a constantly evolving facilitates the production of groundbreaking products. Corn snakes have been at the heart of herpetoculture for decades and with their docile behaviour and hardy nature, are unlikely to waiver in popularity any time soon. Although there a million ways to keep a corn snake healthy, it is those innovative keepers at the forefront of good welfare standards that will be celebrated in the hobby for

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