Reptile Behavior – A Window Into Health & Welfare

Reptile behavior can be fascinating to observe and a window into health & welfare. However, a reptile’s exhibited behaviors can be misinterpreted as abnormal and cause unnecessary stress and discomfort.


For example hognose snakes will demonstrate complex death feigning when harassed by vibr레오파드게코 ating their tail and extending one or both hemipenes. This can be misinterpreted as injury or neurologic disease.

Threat Displays

Many animal species display threats to potential predators and competitors. A dog may bare its teeth and growl, a cat may hiss, a snake may coil up and move back and forth to show off its venomous spines. In some cases, an animal will “freeze” and stay completely motionless if threatened. This is called the freeze reflex.

Other displays involve pointing, inflating the chest or abdomen and a variety of other stances that make an animal look bigger. For example, a frill-necked lizard will flare out its head and neck to appear larger. The display of a Colombian four-eyed frog, Pleurodema brachyops, includes spreading its pincers and raising its abdomen to present a sting. Some snakes bluff by displaying a female snake’s pheromones to fool other males into thinking they are trying to mate with the true female and distract them from engaging in fighting behavior.

In the July issue of the journal The American Naturalist, Kristopher Lappin, Yoni Brandt and colleagues at Northern Arizona University report that male collared lizards in an intense territorial interaction provide their rivals with accurate information 레오파드게코 about their jaw strength by gaping their mouths. This display allows an opponent to evaluate a rival’s ability to bite, which is particularly important because the jaw muscles of these lizards are hypertrophied, meaning they can deliver a serious bite.

Death Feigning

Several reptiles, including snakes and crocodilians, will feign death in response to perceived threats. The feigning behavior is sometimes accompanied by vocalizations and/or the release of urates or feces. This display may be effective in distracting the predator and allowing the prey animal to escape. However, the ability of reptiles to successfully use this technique is not well understood.

Some snakes, such as Asian rat snakes and monitor species, will flatten the caudal and cranial regions of their neck to increase body size during a death-feigning display. The behavior also exposes bright colors that would otherwise be concealed by scales. These displays are intended to deceive a predator into believing the animal is seriously ill or injured, thus providing more time for it to flee (Haan, 1906).

The feigning behavior is observed in many snakes during captivity. Hognose snakes will often display a complex bluffing behavior that involves an exaggerated S-coil, loud hissing, and false strikes with the tail tightly coiled and elevated. If the bluff fails, the snake will often violently thrash and then assume an inverted, limp posture with the mouth hung limply open, frequently excreteing urates and feces.

When handled in the lab, the duration of a snake’s feigning behavior can be quantified by measuring how long it takes for the lizard to return to a normal posture after a disturbance. The lizards are watched from two different distances and the average duration of the feigning behavior is recorded as a measure of the effectiveness of this defensive strategy.

Tail Displays

Reptiles often use visual displays to communicate with each other. These can involve displaying bright colors, head bobbing, dewlap raising, displaying a throat fan or puffing up the gular region. These behaviors serve as social signals for breeding, territory defense and courtship. They can also divert predators from an animal’s vulnerable head to the tail, which may look more durable and easy to manipulate.

Some reptiles, such as zebra-tailed lizards (Callisaurus), display a striped underside of their tail to each other. This behaviour is a form of social communication and has been found in both male and female lizards during courtship.

Many lizard species are territorial and defend their territories from members of the same species. Territories are usually associated with limited resources, such as food and refuges from predators. Displays used during territorial defense include displaying bright colors, erection of crests along the back and neck, and stereotyped movements such as a quick sprint speed, large body size and a high sweep area of tail lashing.

The ability to recognize and interpret a variety of behavioral displays is important for the veterinary practitioner caring for reptiles. Recognition of normal and abnormal behavior can alert the veterinary caretaker to potential disease or health problems at an early stage. This can save animals’ lives and improve the overall quality of veterinary care.


Aggression is a behavior associated with fighting for territory or resources. In captivity, a reptile may engage in this behavior to defend its enclosure or to respond to perceived threats from other animals. Aggression can be a normal part of an animal’s territorial display and it may be accompanied by head bobs, tail lashing or biting attacks. In addition to territorial disputes, aggressive displays may occur during the breeding season and in dominance hierarchies. For example, male iguanas (Iguana rossii) will stalk female iguanas in their aquarium and engage in gaping threat displays followed by full bites to establish dominance.

Interestingly, the level of harm that is induced by a behavioral response can be an important factor in whether or not it is considered aggressive. Generally, the more extreme the harm is, the more aggressive the response. This quality, called extremity of harmfulness, is not included in Parrott and Giancola’s definition of aggression, but it may be considered when interpreting lab-based aggression paradigms.

The extent to which a reptile’s behavior changes with age is not fully understood. However, ontogenic differences in aggression have been identified in natricine snakes and are believed to be a result of changes in the physiology of midbrain regions that control aggression and fear. These differences in aggression may also be a response to stress and/or nutritional status.