Deer are opportunistic herbivores that readily graze on cultivated plants, including the sweet and nutritious cherries that ripen in the summer. While the fleshy part of the cherry is not toxic and provides a welcome, high-calorie food source, the hard pit at the center of the fruit contains a compound that is potentially dangerous. Understanding the specific chemical risk within the pit is the first step in assessing the actual danger to the deer population.
Are Cherry Pits Toxic
Cherry pits contain amygdalin, a naturally occurring cyanogenic glycoside. Amygdalin is not toxic until the pit is crushed or broken down. This action allows it to contact enzymes that convert it into hydrogen cyanide (prussic acid). Hydrogen cyanide is a potent toxin that interferes with the body’s ability to use oxygen, rapidly damaging organs like the brain and heart.
The hard outer shell acts as a protective barrier, separating amygdalin from the converting enzymes. If a pit is swallowed whole and passes intact through the digestive system, hydrogen cyanide is not released, posing little chemical threat. Different cherry varieties contain varying concentrations of amygdalin; for example, sour cherry types, such as the Morello cherry, can contain significantly higher amounts than sweet varieties. Due to cyanide’s high toxicity, even a small number of crushed pits (ranging from three to nine, depending on the cherry type and animal size) could potentially lead to serious illness or death.
Deer Feeding Habits and Cherry Consumption
The practical risk of cyanide poisoning depends heavily on deer feeding behavior as ruminants. Deer consume food quickly, biting and incompletely chewing vegetation before swallowing it into their four-chambered stomach system. This feeding process means that small, hard cherry pits are often swallowed whole and pass through the digestive tract without being crushed.
Mechanical crushing of the pit releases the toxic amygdalin, meaning a whole, intact pit does not pose a chemical risk. Deer are concentrate selectors, preferring highly digestible foods, and cherries are a seasonal, opportunistic food source. While deer consume large quantities of fallen fruit, the pits are unlikely to be fully processed to maximize cyanide release before being eliminated. The sheer volume of crushed pits required for a lethal dose makes poisoning from eating whole cherries a relatively low risk in wild populations.
Toxicity Beyond the Fruit: Leaves and Branches
While the fruit presents a relatively low risk, other parts of the cherry tree are more chemically dangerous. All members of the Prunus genus (cherries) contain cyanogenic glycosides in their leaves, twigs, and bark. This plant material contains the same toxic compounds as the pits, but in a form more readily accessed by the digestive system.
The most significant danger arises when leaves begin to wilt, such as after a branch breaks off or after pruning. Wilting damages the plant cells, allowing the amygdalin and the converting enzymes to mix, which generates a much higher concentration of hydrogen cyanide. For ruminants like deer, consuming wilted cherry leaves is a common cause of fatal poisoning. Homeowners should remove any downed branches or pruning debris accessible to deer, as the wilted foliage poses a far greater threat than the fruit.