North American porcupine

Systematic position. The North American porcupine (Erethizon dorsatum) belongs to the order Rodentia and the family Erethizontidae. It is a large rodent species native to North America, known for its protective quills and its significant impact on forestry and woody vegetation.

Crops damaged. This species is a major pest for both coniferous and deciduous trees. It feeds on the inner bark (cambium) and buds of trees like pine, spruce, hemlock, birch, maple, and various fruit trees. They can cause substantial economic losses in forest plantations and orchards by targeting both young and mature trees.

Biology and life cycle. Porcupines are primarily arboreal, adapted for climbing to reach food sources. They remain active throughout the winter, which is when they cause the most severe damage. They typically reproduce once a year, giving birth to a single offspring, and maintain a solitary lifestyle within their established home range.

Nature of damage and harmfulness. During winter months, when other forage is scarce, porcupines graze on tree bark, often girdling the trunk or branches. This damage disrupts the transport of water and nutrients, leading to crown dieback, increased susceptibility to secondary infections, and potential tree mortality. High-value ornamental or fruit trees can be killed in a single season.

Control measures. Protecting trees requires a combination of strategies:

• Encircling the base of valuable trees with heavy-gauge wire mesh or metal flashing.
• Using chemical repellents specifically formulated for rodent control on bark.
• Implementing silvicultural practices that reduce the attractiveness of the area to porcupines.
• Encouraging populations of natural predators such as fishers, bobcats, and mountain lions.