Researchers have found that Garter Snakes can distinguish themselves from other snakes using scent, not sight.  

Noam Miller, a comparative psychologist at Wilfrid Laurier University in Ontario, Canada, and the research team, conducted cognitive experiments with snakes. Cognitive experiments are designed to study internal mental process, such as attention, perception, memory, and decision-making. Cognitive psychologists think that cognition – thinking and knowledge – can be tested using senses: hearing, sight, smell, taste, and touch.  

One sign of cognition is whether an animal can recognize itself in a mirror – it is a proxy sign for “sophisticated intelligence” in animals. Mirror tests have mainly been conducted with visual animals that rely on their sight: elephants (passed the test), pandas (failed), roosters (passed), etc. 

However, snakes do not rely on their sight – they rely on their sense of smell to detect other animals, food, water, etc. 

The researchers conducted the mirror test with two species of snakes: the North American Eastern Garter Snake (Thamnophis sirtalis sirtalis) and the African Ball Python (Python regius). The researchers also observed how they reacted to a mirror and seeing themselves. They also conducted olfactory tests (smell tests). They collected scent from the oily skin of the snakes and had a control group with olive oil scent. If the snakes flicked their tongues to taste the air it was a sign of interest in the other snake – longer durations of flicking indicated sustained interest. 

The test was called the odour version of the “mark test” in which a mark – a stain or colour – is put on an animal to observe if the animal uses a mirror to locate and examine the mark on its own body (that they would not otherwise be able to see). The odour-based mark test had never been attempted in reptiles before, such as snakes, lizards, alligators, and crocodiles. 

The Eastern Garter Snakes passed the test, and the African Ball Pythons failed the test. 

Eastern Garter Snakes are terrestrial foragers (living and eating on the ground), whereas African Ball Pythons are semi-arboreal ambush predators (living on the ground and in trees). Eastern Garter Snakes are also more social, preferring to be near other Garter Snakes, and there is a theory that social animals are more likely to self-recognize in a mirror test. 

Location of photograph: Spangler Park, Wooster, Ohio, 22 April 2010

Photographer: Wilson44691 Wikimedia Commons, accessed 29 April 2024

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