By Lori Torrini
Paper, cardboard boxes, tubes, tubs, baskets, rocks, branches, empty containers, scents, bedding, and dirt. Are those enrichments? They can be. Creating environmental novelty and complexity can be as simple as using items already found around the house, or repurposing items that would normally be thrown out as trash. Sure, enrichment can be more complicated and expensive, naturalistic or bioactive enclosures with furnishings to rival a forest, but it does not have to be. So, what exactly is enrichment?
Think of enrichment as providing activity options and environmental stimulation. The Association of Zoos and Aquariums (AZA) defines enrichment as: “a dynamic process for enhancing animal environments within the context of the animal’s behavioral biology and natural history. Environmental changes are made with the goal of increasing the animal’s behavioral choices and drawing out their species-appropriate behaviors, thus enhancing animal welfare” (1999 AZA Behavior Scientific Advisory Group).
What does that mean, what’s the purpose? The AZA care manual for the Eastern Indigo snake states “Environmental enrichment, also called behavioral enrichment, refers to the practice of providing a variety of stimuli to the animal’s environment, or changing the environment itself to increase physical activity, stimulate cognition, and promote natural behaviors. Stimuli, including natural and artificial objects, scents, and sounds are presented in a safe way for the snakes to interact with”. The goal of enrichment is to provide animals under human care with mental and physical stimulation. This can be done by providing opportunities to express natural behaviors, but it can also mean giving them opportunities to experience new behaviors they wouldn’t necessarily perform in the wild.
Enrichment can be anything that provides reptiles with an outlet for the physical and mental energy they would normally use for survival and reproduction in the wild. It is to help keep them mentally and physically fit, and to avoid the development of stereotypies. Stereotypies are repetitive behaviors without apparent practical function and may be caused by an animal’s repeated attempts to adapt to its environment, by stress, or by nervous system dysfunction. Stereotypies commonly seen in snakes, for example, include nose rubbing, edging, glass surfing, pushing the nose against surfaces, excessive interaction with transparent boundaries or excessive exploration of the habitat. In cases where these behaviors cease to be reinforcing for the animal or fail to result in meaningful outcomes, learned helplessness may occur and the animal will show little to no activity, failing to express even simple natural behaviors, and may stop eating.
Animals under human care, including snakes and other reptiles, no longer have to use 100% of their energy budget on survival and reproduction because they are being provided with everything they need to live without having to work for it. They now have time to fill and energy to burn and they will find other things to do with it. Of course, the amount of energy will vary by species, but we shouldn’t make assumptions about how much energy that might be. Observe the animals in your care during their active periods, if the species you work with is nocturnal and you can’t stay up to watch them, set up surveillance. This is the only way to truly know how active the animal is and discover if they are displaying any stereotypies.
For example, I am currently doing behavior research with a species purported to be terrestrial and sedentary. They were initially housed in white quarantine tubs with a paper towel for substrate, a water dish, and a hide. When observing the study animals during the day they rested in a hide or on the tub lip; however, at night they frantically moved around their tubs, striking at motion outside of the tubs, edging, pacing the walls incessantly, pushing their noses along the walls and lid, and displaying moderate to extreme stress. I moved them into quarantine tubs with a clear side, added a perch, a humidity hide, and multiple layers of paper towels; the stereotypies and stress behaviors ceased. They rested during the day as before; however, at night they moved around their enclosure in a relaxed and curious manner utilizing the simple items added. They spent time climbing and perching, draping on top of the humid hide or resting inside it, and curiously looking out the clear side with no striking. They also burrowed under the layers of paper towels in an exploratory fashion, not in a manner to indicate they were trying to hide. Without observing the animals at night, their stereotypies would not have been apparent. The addition of three simple items (a perch, a moss box, and additional paper towels) paired with a clear side to see out of the bin immediately changed their behavior.
It is also worth pointing out that while providing opportunities for reptiles to express natural behaviors under human care is a key component in optimal welfare, they are in captivity. They are not in a natural environment, so don’t limit your ideas for environmental stimulation to only those activities you think an animal would do in the wild. I have a Western Hognose snake that uses perches to climb and to get into an ambush position when she is really hungry. That is my clue it’s time to feed her. A colleague of mine has a Kenyan Sand Boa that spends a portion of each day climbing and who seeks time out in the open to explore the environment. Although I have not observed it myself, a few people have reported to me that their Carpet Pythons do some burrowing. These are a few examples of behaviors that may be observed outside the range of what would be natural for them to exhibit in the wild. As long as it is safe for the reptile, enrichment options outside the realm of presumed natural behaviors should not be ruled out.
A reptile that is both mentally and physically fit is going to have greater overall fitness, reproductive success, and longevity. Consider providing outlets for them to use their time and energy, whether it is a little or a lot, in healthy ways. Enrichment doesn’t have to be elaborate or complicated; be creative, anything safe can work. In general, there are five categories of enrichment to consider and they will overlap. These are cognitive, dietary (food), physical, sensory, and social. Some will be more relevant to certain species of reptiles than others. Social enrichment, for example, will not be as relevant to snakes as physical enrichment may be.
The following are some options for consideration within each of the five categories. While you can be extremely industrious and create complex enrichment for your animals, the options mentioned here will be simple, easy, inexpensive ideas that anyone should be able to do with common items. Remember that enrichment should be stimulating and not stressful. When introducing enrichment items to reptiles watch for any signs of moderate to severe stress. If the animal shows signs of moderate stress that diminishes quickly, that is a natural response to a novel item and is fine; however, if the moderate stress does not diminish or if it escalates to severe stress, remove the item or return the animal to a familiar environment where it feels safe.
Cognitive enrichment is anything that stimulates the reptile mentally. Contrary to what many people believe, snakes and other reptiles have the ability to problem solve, learn, and adapt their behavior accordingly. They have not survived millions of years of evolution by just being lucky. Reptiles are not outliers when it comes to brain anatomy. They have the same basic brain plan as other vertebrates. The general brain regions found in mammals, including the cerebral cortex, have homologies in reptiles. These include the forebrain, midbrain, and hindbrain as well as a structure known as the dorsal ventricular ridge researchers believe is homologous to the mammalian neocortex. To this point the Orianne Center for Indigo Conservation (OCIC) makes cognitive enrichment a high priority stating “Behavioral enrichment and modes of learning for juvenile D. couperi will be essential in preparing snakes for reintroduction and may have important husbandry implications of all managed populations. The OCIC will create stimulating environments to increase exercise and promote both psychological and physical fitness. These techniques will also increase the fitness of snakes scheduled for release by helping them develop hunting skills and enhancing their problem-solving aptitude. This is a new field of research that will explore the relationship of cognition to adaptation” (OCIC).
For snakes under human care, cognitive enrichment can be as simple as placing novel items into your reptile’s enclosure for them to investigate, or placing your reptile in a novel environment to explore. You can also provide mental stimulation by providing puzzles for them to solve or mazes for them to figure out. Typically puzzles and mazes have food placed within them and the animals have to find it or figure out how to get to it. Sometimes placing a scent within the puzzle or maze is also enticing for them, and the objects themselves with nothing inside can stimulate curiosity. Some of the best things to use for this are empty boxes, empty paper sacks, empty plastic containers, paper or plastic cups, tubes made of plastic or cardboard, crumpled up paper, or anything safe for your reptile to climb through, in, around, or on. Boxes are extremely popular with my own snakes, especially a whole bunch of boxes in a pile. Boxes that arrive with deliveries or empty boxes that were to be thrown away, think empty cereal boxes for example, are fine to use. So many things come in boxes, why not let your reptiles use them for a while before tossing them out?
For really industrious keepers or those who may also dabble in animal training, you can teach your reptiles to follow a target, go to a station, and respond to visual or other cues to perform specific behaviors. The training itself is cognitive enrichment for your reptile. This is done frequently with many lizards and crocodilians, but don’t underestimate the ability of other reptiles, such as snakes, to learn novel behaviors. In an amazing training study published in 2014, researchers were able to teach wild Burmese Pythons (Python bivitattus) to press a button, but only when it was illuminated, to open a door leading to food. I have first-hand experience training snakes to do things I would not have thought possible just a few years ago.
Be creative with your cognitive enrichment, anything that is safe and mentally engages your reptile will work. Hiding food inside boxes or empty plastic storage containers is a popular activity with my bull snakes and cornsnakes for example, and the activity can be set up inside or outside of their enclosure.
Physical enrichment is simply encouraging your reptile to move. Physical exercise can be stimulated in part by the other enrichment categories cognitive, dietary, sensory, and social. Encouraging your reptiles to climb, burrow, balance, move from one location to another, swim, grip, grasp, etc. can be as simple as adding objects of various heights, sizes, shapes, and textures to the enclosure. Movement can also be encouraged by adding various temperature gradients that are far enough apart to stimulate travel between them. Adding scents to something inside the enclosure can stimulate curiosity, causing movement to the location of the scent. Encouraging reptiles to forage or hunt for their food is also a form of physical enrichment. This can be accomplished by hiding prey items, creating puzzle feeders, or placing food in mazes all of which means the reptile has to move around to get to their food.
For terrestrial and climbing reptiles, it is easy to place containers inside habitats that reptiles can climb through, on, in, or around. Cylindrical objects, properly cleaned branches from outside, or even thick ropes encourage climbing, gripping, grasping, coiling, and balancing. Laundry baskets are popular climbing areas for many of my snakes, as long as they can fit through the holes; and one of my pythons spent over an hour moving rectilinearly back and forth across a thick clothesline type rope one evening.
For terrestrial or fossorial snakes who may burrow, providing substrate options is a great way to encourage movement from one location to another and allow physical burrowing. This can be accomplished by dividing the enclosure floor in half or into thirds and placing a different substrate type in each section. Substrates can also be placed into shallow boxes or inside tubs giving the snakes or other reptiles various locations they can move to and experience the difference (i.e. aspen in one, paper in one, mulch in one, eco-earth, moss, bark, coconut husk, or others). Some of these snakes may also utilize shallow pools of water, mud, or damp substrates.
For aquatic or semi-aquatic reptiles, or even for those who just like to swim from time to time, consider providing a swimming pool separate from their drinking water. This can be accomplished with large bowls, or filling tubs or bins with water. Plain water can be made more environmentally stimulating by placing a rock or rocks in the bottom, or adding other items that are safe to get wet that the reptiles can climb on or grip onto while in the water.
Remember physical enrichment is likely going to be utilized during an individual’s normal active periods which may not necessarily coincide with when you are watching them. If you only see your reptile during the day and its nocturnal, don’t expect to see much activity and don’t assume they are sedentary. They are likely very active in the middle of the night while you are sound asleep. Your snake or other reptile may also be less active during an ecdysis cycle; and, you will likely notice changes in activity level right before or after a meal, during winter versus summer, or during reproductive cycles. Give your reptile time to discover if the enrichment item is something they will use or not, it may take several days or weeks. Just because they did not use it within the first day you gave it to them does not mean they won’t ever use it. Some reptiles are immediately curious and investigate novel items while others are cautious and may find new items reinforcing over time.
Consider a change of locations to promote physical enrichment. Allowing the reptile to come out of their normal living space for supervised time in a designated indoor or outdoor exercise space can encourage movement. This will also overlap with cognitive enrichment by providing mental stimulation in addition to the physical. This will not be appropriate for all animals or keepers; however, for those who are able to provide it, freedom outside of the enclosure becomes very reinforcing for some reptiles. This should be voluntary and not forced, remember the point is to benefit the animal, not cause it distress.
Sensory enrichment has been covered somewhat in other sections but here are some specifics. Visual, auditory, olfactory, gustatory, and tactile stimulation are all forms of sensory enrichment. The importance of each will be species dependent as some reptiles have poor vision and will not be as enriched by visual stimuli as those with keen vision. Research your reptile’s biology and natural history to find out which sensory modalities are relevant to them and focus on those. Make sure sensory and other enrichment items are not able to be swallowed by your reptile and make sure they cannot injure their teeth or themselves on them if they get excited.
Visual enrichment can include novel objects, varying colors, varying contrasts, movement, light, target training, station training, and objects the reptiles can see moving around or cause to move, such as balls.
Auditory stimulation can be any sound the reptile reacts to with interest and curiosity, avoid noises that induce stress or seem to cause agitation. You will have to research your particular reptile’s auditory range for this category.
As with auditory, olfactory stimulation can be any scent the reptile responds to with interest and curiosity. For example, one of my Bredl’s Pythons spent several hours smelling a crumpled-up piece of paper that I had placed a few drops of lavender oil on. The same snake spent over a day engaged with a hide inside his enclosure that I placed a “fruity” smell on.
Gustatory enrichment is anything the reptile can “taste”. For reptiles that have a developed sense of taste or for those whose sense of taste is strongly linked to their sense of smell, you can place small amounts of novel food items or scents on objects for them to taste or lick. Make sure that whatever is used would be safe for the reptile if they were to actually ingest or absorb any of the gustatory enrichment. Many reptiles, including some snakes, will lick water droplets off of glass or other smooth surfaces. Many of my snakes will spend time doing this if I spray the insides of their enclosure walls. Be creative and don’t be afraid to try things as long as they are safe for your animal.
Tactile enrichment is perhaps one of the easiest. As long as it is safe for the reptile you can give them access to any item of varied texture. Consider things like cardboard, plastic, ceramic, wood, logs, branches, leaves, any kind of safe substrates, cloth, stuffed animals, pillows, paper, rubber, etc. Tactile stimulation can include objects that are wet, moist, dry, squishy, hard, soft, rough, smooth, bumpy, cold, cool, warm, hot, or combinations of these things. Please remember that the objects must be appropriate for the species, make sure the animal doesn’t try to eat something it shouldn’t or get burned by something.
Food enrichment is anything that makes the eating experience more involved than being fed in a bowl, on a plate, or with tongs. Encouraging the reptile to find their food through hunting or foraging enriches and prolongs the experience. This is easily done via mazes or puzzles which can be created with empty boxes or other containers, hiding food inside the enclosure or a separate space, presenting food as a reinforcer during training sessions, freezing food in ice cubes, placing food in water, creating movement of the food, or feeding live (if appropriate, safe, within your personal ethics, and allowed by law).
Use only those options that are safe for the reptile and appropriate for the species. The behaviors you will observe are likely to vary between species. For example, when setting up foraging exercises for my bull snakes they are quick to find the prey, consume it, move on, and continue foraging. When my pythons participate in this same exercise, they move with slow deliberation following the scent trail, cautiously approach the food item, watch and smell it for a while, and then consume it or do not consume it until I wiggle it first. Once they have eaten the food, they will remain in ambush posture in that same spot for several hours prior to moving on, and when given the opportunity will return to that same spot over and over again to take up an ambush position.
Anything that extends the process of obtaining a meal, encourages physical movement, requires problem solving, and utilizes the senses, falls under food enrichment even as it overlaps with the other categories.
Social enrichment is just what it sounds like, interaction with others. Reptiles are typically thought to be non-social with a few exceptions; however, even those species that are generally solitary may benefit from the mental excitement of encountering a conspecific. This can be done by placing enclosures near each other where they can see and smell one another, by placing sheds from one animal in the enclosure of another, or by swapping an item from one animal’s enclosure into another’s. Obviously, these options will also be applicable to the sensory category of enrichment because they involve smell. For reptiles not known for combat or agonistic behaviors, or who are known to be social, it can be beneficially stimulating for them to be placed out in a large area together for supervised periods of time and later returned to their own habitats.
This brings us to the often-controversial subject of cohabitation. This may benefit some reptiles, under certain conditions, when housed appropriately but is a complex behavioral subject. It is very species specific, here is an example: the AZA Eastern Indigo Snake care manual advises against cohabitation and social interactions for this species due to agonistic behavior and cannibalism, while the AZA Eastern Massasauga Rattlesnake care manual states this species may be “successfully housed in a variety of social configurations. Individual animals, mixed sex, and single sex groups can be housed for long periods without apparent problems. These snakes appear to be very tolerant of conspecifics. Rattlesnakes are often communal hibernators and there are no known reports of injurious interactions between animals”. Cohabitation is a complex form of social enrichment that may be appropriate for certain species. This must be thoroughly researched for individual species and is not for the beginner keeper.
Interaction with other species of animals, including humans can also be a form of social enrichment that some reptiles may benefit from. Seeing, touching, and smelling other animals can be intriguing for reptiles. Use caution to make sure any such interactions are supervised and done in a safe manner for all involved. This will not be appropriate for all reptiles and some get along better around certain species and not others. Do your research about inter-species interactions first before putting two animals in the vicinity of each other and if you are unsure how two species may react to one another, do not do it.
An example of interspecific interaction I can share is that of a Bull Snake and Box Turtle at the AZA accredited Pueblo Zoo who share a habitat. Although they have multiple resources and options such as multiple hides, every time I have observed them, they were sharing the same hide together. I could speculate as to why, but the “why” is not as important as recognizing that they are choosing to do that. If they did not find value in the behavior, if it were not in some way reinforcing to them, they would not do it.
In conclusion, enrichment for snakes and other reptiles should consider the natural history of the species, the personality and temperament of the individual animal, the reptile’s current environment, the skill and comfort level of the keeper when interacting with the animal, the overall health of the animal, the safety of the enrichment items, and the stress level of the animal. Enrichment experiences should be something of value that reptiles find meaningful to them and should have a beneficial impact on their health or welfare.
