Behaviour in the wild
Reptiles as a group vary widely in their natural history. They are found in an array of habitats and ecological niches, including the following:
- The temperature extremes of the desert (hot by day, cold by night)
- The heat and humidity of the tropical rainforest
- Freshwater creeks and rivers
- Salinity of marine environments
- Urban areas
Reptiles may be aquatic, terrestrial, arboreal, or subterranean (in the water, on land, in trees, or underground) or in many cases some combination of these depending on stage of development and time of year. Reptiles have adapted physically, physiologically, and behaviourally to each of these vastly different conditions, not just surviving but also thriving. Therefore, it’s unreasonable to assume that one captive environment will suit every species or individual.
Environmental enrichment is defined as “the stimulation of the brain by its physical and social surroundings in an attempt to reduce or overcome problems caused by containment”. The goal of environmental enrichment is to provide opportunities for your captive reptile to display behaviours more like the normal behaviour of reptiles in the wild.
Reptiles who are behaviourally well-adapted to their environment will display normal (or near normal) ‘species‐specific behaviour’ (as permitted by their social and physical environment) and not abnormal behaviours. Reptiles who are not adapting well display a range of abnormal behaviours, including:
- Inflation of the body
- Escape attempts e.g., rubbing their face on the enclosure sides (you may see resulting abrasions on the front end of the reptile’s body)
- Rapid gular pulsation (rapid throat movements)
- Mock or actual attacks e.g., striking at the glass when you walk by
- Open mouth defence posture ‘Clutching’ object or handler e.g., pythons that constrict tightly when handled
- Open mouth breathing
- Feigning death
- Defecation when handled
- Hiding head
- Projection of their hemipenes
- Pigmentation change
Environmental enrichment should therefore be seen as a means of both preventing and, to an extent, treating these abnormal behaviours.
What does my reptile need to be comfortable?
To maintain your reptile’s comfort, happiness, and sense of safety and security, they need environmental enrichment.
A key concept in environmental enrichment requires that we know ‘species‐typical’ information. It is then important to select enriching strategies that are behaviourally relevant and physically feasible for your reptile. Designing an enrichment plan that is incompatible with their normal behaviour, physical attributes, or existing environment may not only be fruitless but may also cause frustration and potential harm. Doing it well though, allows normal behaviours to occur and provide a level of stimulation and activity that leads to good physical, mental, and emotional health.
The natural history of each species is important to keep in mind when developing a safe and effective enrichment program. Considerations include:
- Feeding: Reptiles use a variety of food types and feeding strategies. Some are herbivores, others are insectivores or carnivores, and many are omnivores. Some are primarily predators (hunters or ambush predators), while others are primarily prey (most are both to some extent).
- Locomotive styles: Reptiles may be arboreal (tree-dwellers), terrestrial (ground-dwellers), or semi-aquatic. They move around by walking, slithering, climbing, and swimming.
- Social and reproductive behaviours: These include excavation of nests or burrows, sexual displays, and territorial displays. Some of these latter behaviors may only occur in a social context, though reptiles range from gregarious (social) to relatively solitary lifestyles.
- Temperature: Reptiles are ectothermic animals. Because their body temperature is dictated by external temperature, reptiles can regulate their body temperatures through behavior.
- Water: Reptile life and reproductive cycles are influenced by the availability and quantity of water. In some species the amount of moisture in the air is critical while in others, access to a pond, lake, river, or estuary is essential for their health.
The first step in developing an enrichment program for your reptile is to research the normal (wild) behaviours of the species you hold, and factor in the above considerations into your plan. This plan should contain elements of:
- Foraging enrichment – seeking out food.
- Physical enrichment – an environment that stimulates normal physical activities.
- Sensory enrichment – allows your reptiles to use sight, sound, taste, smell, and touch in their daily life.
- Social enrichment – does your reptile need a companion?
- Occupational enrichment – giving your reptile some choice over their daily activities.
Examples of foraging enrichment can include:
- Providing naturally rotten logs with insects. Note that there are potential welfare and ethical considerations with the feeding of live insects to reptiles to think about; for more information see this article.
- Insect dispensers e.g., fake log with timed release insects on a random schedule.
- A variety of insect prey.
- Hand scattering of routine dietary insects can also be enriching if the quantities are unpredictable and fed at irregular intervals.
- A varied feeding schedule of prey items can lead to an increase in predatory behavior and therefore an overall increase in activity.
- Scent trails, made by dragging a dead prey item around the enclosure and then hiding it under substrate such as leaves or enclosure furniture.
- Nontoxic browse for herbivorous reptiles. (These can also be used as temporary perching while they feed.)
Examples of physical enrichment include:
- Perches can be positioned to allow for basking sites with thermal gradients. They also provide arboreal access and encourage climbing. Regular changing of perching can stimulate activity and maintain a healthy environment.
- Misting, whether by hand or via an automated system, can also increase activity and assist with the shedding of skin. Water features (shallow or deep pools, water cascades etc.), where appropriate, can help make the enclosure landscape more interesting and raise the humidity level. Additions of plants, moss, and soil can also help to maintain humidity and moisture. However, care must be taken to achieve a balance – excessive humidity can lead to skin problems, especially in desert-dwelling reptiles.
- Natural substrate, such as soil, wood chip, moss, leaf litter, orchid bark, sand, etc. can give reptiles the ability to manipulate their environments and engage in natural behaviors such as excavating a burrow or creating a nest site. However, a compromise must be made between the enrichment effect and good hygiene.
- Shelters help your reptile feel protected while still being visible. Providing them with more than one sheltered location across either temperature (e.g., one near a heat source and one in a cool place) or moisture gradients (e.g., one that uses moist moss, another, dry leaf litter) permits the animal to make choices while still having shelter. For some snakes, the addition of a “hide box” to the enclosure promotes eating.
- Increased enclosure size to add complexity, facilitate thermal and humidity gradients, and increase activity and behavioral repertoire of the animals.
- Chemosensory behaviour in snakes can be stimulated with the addition of a shed of another (healthy, parasite free, etc.) snake. This will typically elicit tongue flicking and olfactory investigation.
Many reptiles e.g., bearded dragons, blue-tongue lizards, and many pythons are, by nature, solitary creatures that only come together for breeding. Some of these reptiles, forced into shared co-habitation, may fight with each other and, in some cases (such as black-headed pythons), kill and devour their cagemate. Conversely, Cunningham skinks (Egernia cunninghami) are very social lizards, living in stable groups of up to 20-30 individuals and displaying monogamous behaviour.
Keeping two reptiles in the same enclosure is therefore something to be researched beforehand and monitored closely afterwards. Care should be taken to select species that will tolerate one another well without predation, aggression, an unhealthy amount of social stress, or undue dietary competition.
Giving a reptile choice over their environment can be achieved by:
- An enclosure large enough to move around freely without becoming ‘lost’.
- Providing climbing perches and basking spots
- Using thermal gradients to allow your reptile to be comfortable.
- The provision of shelter to allow not only a hiding spot, but also for thermoregulation.
When environmental enrichment activities are being planned, it is vital to consider the safety of both you and your reptile.
- Enrichment in an enclosure can create new opportunities for escape or injury and therefore should be well planned out in advance.
- Ventilation must not be compromised by new items in the enclosure.
- Modifications to an existing habitat can create new hazards, such as perching placed too close to cage mesh causing skin abrasions, or unshielded heat lamps causing burns.
- The potential for your reptile to become stressed by changes to their environment should be considered.
- There is no single substrate (the surface on which your reptile lives) that is acceptable across all terrestrial reptile species. Some may be too absorbent and cause a decrease in the humidity level in the enclosure, leading to dehydration; others may not absorb well enough and cause too great of a moisture build up. The frequency with which the substrate will need to be changed to maintain hygienic conditions will depend greatly on the type of substrate, the species housed with it and how they are maintained (e.g., how frequently are they misted, number of animals, etc.). Substrate can be a great asset in an enclosure; when used appropriately, the benefits of its use will, in most cases, far outweigh the risks.
- Live prey items (e.g., crickets) can pose potential danger if not eaten immediately as they can bite and injure the animal being fed. This risk can be minimised by monitoring the situation and not leaving live prey in the enclosure for any length of time if the reptile seems uninterested. Note that there are potential welfare and ethical considerations with the feeding of live insects to reptiles to think about; for more information see this article.
- Reptiles frequently carry Salmonella in addition to many other transmissible pathogens that pose a risk to both humans and other reptile species. This should always be a consideration when cleaning or rearranging an enclosure.
Burghardt G (2013) Environmental enrichment and cognitive complexity in reptiles and amphibians: Concepts, review, and implications for captive populations. Appl Anim Behav Sci 147:286–298
Carmel B, Johnson R (2014) A guide to health and disease in reptiles & amphibians. Reptile Publications, Burleigh
Chapple D (2003) Ecology, life-history, and behavior in the Australian scincid genus Egernia, with comments on the evolution of complex sociality in lizards. Herpetological Monographs 145–180
Frederick C Reptile enrichment guidelines. Accessed 22 Jun 2023
Johnson R (2017) Behaviour in the Wild and in Captivity. In: Doneley B, Monks D, Johnson R, Carmel B (eds) Reptile Medicine and Surgery in Clinical Practice. pp 33–43
Healey M Carpet Python Care Sheet on Reptifiles. Accessed 22 Jun 2023