Large, dark-colored snakes across North America often lead to questions about their hunting methods. Many people assume any large black snake must kill its prey by squeezing it. This assumption creates confusion, as the term “black snake” applies to several distinct species with different hunting strategies. Clarifying the mechanics of constriction and distinguishing between the two most common black snakes in the eastern United States helps resolve this misunderstanding.
Understanding the Mechanics of Constriction
Constriction is a specialized hunting technique used by many non-venomous snakes to subdue and kill prey. Modern scientific research shows the process is rapid and efficient, relying on the circulatory system rather than crushing bones or causing suffocation.
When a constrictor strikes, it quickly wraps its body around the prey, applying pressure that interrupts blood flow to the heart and brain. This sudden pressure drop induces rapid cardiovascular collapse. The prey loses consciousness within seconds and dies from ischemia, which is the lack of oxygen reaching the brain. The snake monitors the prey’s heart rate until it stops, confirming death before swallowing the meal whole.
The Primary Constrictor: The Black Rat Snake
The Black Rat Snake (Pantherophis) is one of the most common species to employ constriction. This large, powerful snake is a true constrictor, known for its ability to climb vertical surfaces like trees and brick walls in search of food. The Rat Snake is highly beneficial to agricultural areas because its diet primarily consists of rodents, such as rats, mice, chipmunks, and voles.
Due to its arboreal nature, the Black Rat Snake is also a significant predator of birds and their eggs, often raiding nests high off the ground. Once it secures a meal, it uses the precise, blood-flow-stopping squeeze of a constrictor. This behavior allows the snake to efficiently overpower prey, ensuring a quick kill before consumption.
The Non-Constrictor: The Black Racer
The Black Racer (Coluber constrictor) is the other highly common black snake frequently encountered across eastern North America. Despite its scientific name, the Racer does not use the specialized coiling and squeezing technique of a true constrictor. The name is an artifact of older classification systems that incorrectly grouped it with constricting species.
The Black Racer is an active, diurnal hunter that relies on speed and excellent vision to catch its meals. Instead of subduing prey with coils, the Racer chases down victims, pinning them to the ground with a loop of its body or holding them firmly in its jaws. It then swallows the prey alive or immobilized, without the specialized squeeze that causes cardiovascular collapse.
The Racer has a broad diet that includes insects, lizards, small snakes, frogs, and small rodents. Unlike the Rat Snake, which often remains motionless, the Racer is known for its nervous temperament and tendency to flee quickly when approached. This contrast in hunting style illustrates why the blanket term “black snake” cannot determine a species’ hunting method.