Some researchers have insisted that not enough is known about behaviour of captive reptiles such as snakes, and that they can indicate disturbance, disease, and injury just as in other animals (Warwick C et al., 2013). They summarized behavioural signs of captivity stress in the table below. The researchers believe that there are many behavioural signs that reptiles are stressed in captivity (and perhaps only some can be attributed to snakes) (Warwick C et al., 2013). They also believe that there appears to be a lot of misinformation spread to convenience reptile hobbyists such as repeating that reptiles are mostly sedentary and enjoy long periods of inactivity resulting in the keeping of the animals in enclosures that are far too small (Warwick C et al., 2013).

Behavioural signs of captivity-stress

Behaviour Sign Possible cause
Interaction with transparent boundaries (ITB) Persistent (up to 100 per cent activity period) attempts to push against, crawl up, dig under or round the transparent barriers of enclosure Related to exploratory and escape activity. Self-compounding and destructive. Inherent psychological organisation and adaptational constraints result in failure to recognise abstract invisible barriers
Hyperactivity Abnormal high-level physical activity, surplus or redundant activity Often associated with ITB. Overcrowding. Self-compounding and destructive. Overly restrictive, deficient and inappropriate environments
Hypoactivity Hypothermia, disease, injury, pain, co-occupant harassment Too low temperature, infection/organic dysfunction, falling, dropping, co-occupant attack, transport trauma, occupant harassment
Anorexia Hypothermia, disease, injury, pain, co-occupant harassment Too low temperature, infection/organic dysfunction, falling, dropping, co-occupant attack, transport trauma, occupant harassment
Hyper alertness Abnormal high level of alertness ‘nervousness’ to environmental stimuli Often related to fear, defence and escape behaviour. Common in overly restrictive, and exposed, deficient and inappropriate environments
Rapid body movement Abnormal ‘jerky’ locomotor or jumping actions Often related to fear, defence and escape behaviour. Common in overly restrictive, and exposed, deficient and inappropriate environments
Flattened body posture Flattening of body against a surface often combined with hyper alertness Often related to fear, defence and escape behaviour. Common in overly restrictive, and exposed, deficient and inappropriate environments
Head-hiding Deliberate seclusion of head including under objects or substrate Often related to fear or ambient light/photo stress behaviour. Common in overly restrictive, and exposed (including excessive ambient light for nocturnal species), deficient and inappropriate environments
Inflation of the body Deliberate (often repeated) inflation and deflation of the body. May or may not be associated with ‘hissing’ sound Often related to fear, defence and escape behaviour. Common in overly restrictive, and exposed (including light for nocturnal species), deficient and inappropriate environments
Hissing Hissing sound, accompanied with deliberate repeated inflation and deflation of the body Often related to fear, defence and escape behaviour. Common in overly restrictive, and exposed (including excessive ambient light for nocturnal species), deficient and inappropriate environments
Co-occupant aggression Aggressive or defensive displays, biting, chasing cage mates Often related to courtship routines, inability to avoid cage-mates when required, overly restrictive, and exposed deficient and inappropriate environments. Hunger
Human-directed aggression Mock/real strikes using jaws or tail Often related to fear, defence and escape behaviour. Common in overly restrictive, and exposed (including excessive ambient light for nocturnal species), deficient and inappropriate environments.
Clutching Snake or lizard tightly grasps human or object Often related to fear or ambient light/photo stress behaviour. Common in overly restrictive, and exposed (including light for nocturnal species), deficient and inappropriate environments
Death-feigning Animal (commonly snake) appears limp, upside-down, unconscious Often related to fear
Loop pushing Snake uses ‘arch’ of body to resist/deflect physical contact from cage-mate or human Often related to fear or ambient light/photo stress behaviour. Common in overly restrictive, and exposed (including light for nocturnal species), deficient and inappropriate environments
Freezing Eye contact with or general presence of observer results in freezing posture/tense immobility Often related to fear or ambient light/photo stress behaviour. Common in overly restrictive, deficient and inappropriate environments
Grating of jaw Turtles and tortoises tightly rasp together ramphotheca causing an abrasive grating sound Often related to fear or light stress behaviour. Common in overly restrictive, and exposed (including ambient light/photo for nocturnal species), deficient and inappropriate environments. Pain
Hesitant mobility Animal uncharacteristically moves in ‘fits and starts’ Often related to fear. Common in overly restrictive, inappropriate environments
Wincing Hypersensitivity to minor stimuli causing retraction of head, limbs or tail Often related to fear. Common in overly restrictive, inappropriate environments. Pain, disease
Prolonged retraction of head, limbs or tail Tortoises and turtles retracting head, limbs or tail for minutes or longer Often related to fear, pain, disease
Open mouth breathing Sporadic, usually slow, open-mouth respiration or gasping Hyperthermia, infection/organic dysfunction/disease, major head/neck injury, falling, dropping, co-occupant attack, transport trauma
Panting Rapid open-mouth breathing, sometimes accompanied by extension of dewlap (skin flap under lower jaw in lizards). Hyperthermia
Also, cloacal evacuations may occur
Cloacal evacuations when handled Urination, defecation, excretion of malodorous substance from cloaca Often related to fear
Projection of penis or hemi-pene Projection of penis or hemi-pene associated with human presence or contact Often related to fear
Voluntary regurgitation of food Regurgitation of food associated with human presence or contact Often related to fear
Tail autotomy Voluntary autotomy of tail (some lizards) associated with human presence or contact Often related to fear
Pseudo vocalisation Crocodilians, some lizards and turtles producing squeaks or whines (aside from sexual context) Often related to fear, physical irritations, pain, injury, disease
Venom spitting Venomous snakes ejecting venom associated with human presence or contact Often related to fear
Squirting blood from eye Some lizards eject blood from eye associated with human presence or contact Often related to fear
Pigmentation change Typically, some lizards (especially chameleons) change colour – may be rapid or slow Often related to fear, pain, hyperthermia, hypothermia, overly restrictive, deficient and inappropriate environments, injury, disease
Atypical locations Reptile occupies an atypical location for an unusual amount of time or another unusual context (e.g., an arboreal chameleon on cage floor) Often related to disease, injury, discomfort, co-occupant aggression, hyperthermia, hypothermia

Figure constructed by Warwick C et al., 2013.

The same author echoed these sentiments in another paper insisting spatial considerations for snakes are often far too small (Warwick C et al., 2019). This was in reference to the fact that although capable of compacting themselves, snakes need the ability to extend fully. In many conditions involving hobbyists and zoos, they are not capable of doing so (refer to the figures below) (Warwick C et al., 2019). They need to exhibit this straight-line orientation during times of locomotion and rest and in times where lateral motion is limited. These orientations are viewable in the figures below. It should be noted that in all of these cases, snake mobility is moderately to severely limited.