The diet of any animal reflects its size, habitat, and evolutionary history, which is true for the diverse group of reptiles commonly known as “brown snakes.” Understanding what a brown snake eats reveals a story of specialization, ranging from tiny, soft-bodied invertebrates to large, active vertebrates. This exploration highlights how two completely different groups of snakes, separated by continent and evolutionary path, have adopted the same common name while maintaining vastly different menus.
Clarifying the Identity of Brown Snakes
The common name “brown snake” causes significant confusion because it refers to two distinct groups of reptiles with radically different characteristics and diets. One group is the North American Dekay’s Brown Snake (Storeria dekayi), a small, non-venomous species found across the eastern United States and parts of Canada. This species rarely exceeds a foot in length and is harmless to humans. In contrast, the term also refers to the Australian Brown Snakes (Pseudonaja genus), which include some of the most venomous snakes in the world, such as the Eastern Brown Snake (Pseudonaja textilis). These Australian species are large, fast-moving, and pose a serious threat, routinely growing to over six feet long.
Diet of the North American Brown Snake
The North American Dekay’s Brown Snake (Storeria dekayi) maintains a specialized diet focused almost exclusively on soft-bodied invertebrates. Their small size and secretive, subterranean lifestyle mean their prey must be easily overpowered and found within leaf litter or under logs. Their diet is largely composed of slugs, earthworms, and snails, which they actively hunt in moist environments. The consumption of snails is a noteworthy adaptation, as these snakes have specialized jaws and teeth that allow them to extract the snail’s body from its shell. This unique ability makes them effective biological controls for garden pests. While primarily consuming these items, they may occasionally eat insect larvae or small salamanders. Adult females sometimes increase their slug intake during gestation to meet the metabolic demands of reproduction. These small snakes are an integral part of the detritus food web in their native habitats.
Diet of the Australian Brown Snake
The Australian Brown Snakes (Pseudonaja species) primarily consume vertebrate prey. As formidable predators, they target a range of animals including small mammals, birds, and reptiles. This preference for warm-blooded prey, especially rodents, has allowed the Eastern Brown Snake to thrive in agricultural and semi-urban areas where human activity provides abundant food. Larger adults often show a preference for mammals, sometimes becoming mammal specialists. However, they are generalists and will readily consume other reptiles, including lizards and even other snakes (ophioophagy). Juveniles rely more heavily on smaller lizards until they are large enough to subdue mammals. The shift in diet from reptilian prey in juveniles to mammalian prey in adults is correlated with a change in their venom composition, specifically in the activity of their procoagulant toxins. This suggests their venom has evolved to efficiently incapacitate the specific type of prey they target at different sizes.
How Brown Snakes Hunt and Acquire Prey
The methods brown snakes use to find and subdue their meals reflect their respective ecological niches. The North American Brown Snake, Storeria dekayi, is primarily a nocturnal, active forager. It uses its sharp sense of smell and forked tongue to locate and track the scent trails of slugs and earthworms hidden under leaf litter or soil. Once prey is located, they subdue it without venom, grasping it and immediately beginning consumption. Their specialized dental structure assists in holding and manipulating soft-bodied prey like snails for extraction. This non-venomous technique relies on stealth and mechanical advantage, which is sufficient for their small, slow-moving invertebrate targets.
In contrast, Australian Brown Snakes are generally diurnal, fast-moving predators that actively hunt across open ground. They utilize sight, vibration detection, and chemical sensing to pursue their faster, vertebrate prey. When prey is captured, the snake relies on its potent neurotoxic and procoagulant venom to quickly incapacitate or kill the meal. The swift action of the venom is necessary for subduing struggling, warm-blooded prey before it can escape or injure the snake.