Abert's Squirrel

The Abert’s squirrel (Sciurus aberti) is restricted to the ponderosa pine forests of the Colorado Plateau and southern Rocky Mountains of Colorado, Utah, Arizona and New Mexico in the United States and the Sierra Madre Occidental of Chihuahua and Durango in Mexico. The GMUG National Forest is located well within the range of this species. Most of the known populations are found on the Uncompahgre Plateau and Naturita Division of the Uncompahgre National Forest.

The Abert’s squirrel is dependent upon ponderosa pine for food, cover and nest sites. Preferred habitats are composed of all-aged ponderosa pine stands with trees in even-aged groups. Abert’s squirrels are active throughout the year. Their diet shifts with the seasons and availability of food. They consume the seeds, inner bark, terminal buds and staminate flowers of ponderosa pine along with Gambel oak acorns, fleshy fungi, carrion, bones and antler. The most nutritious food source is the seed of the ovulate cones, which are produced by mature trees. The availability of pine seed varies widely since cone crops vary markedly from year to year. The inner bark of subterminal twigs is a reliable source of food that is used primarily in the winter and spring of the year. Abert’s squirrels seem to select certain trees (feed trees) for their quality of twig growth, apparently based on tree vigor. Fungi are the primary food source in summer and fall. Squirrels feed on a variety of mushrooms and particularly seek out hypogeous fungi found growing in association with ponderosa pine tree roots. These mycorrhizal associations are primarily associated with dense canopy stands of black jack pine with deep layers of needle duff.

Abert’s squirrel nests have been studied extensively, and several relationships have been described for cover requirements for nesting. The most important components are tree density, diameter and a grouped distribution of trees. Nests are located in the upper limbs of a tree that is situated within a group of 3 to 5 trees with interlocking crowns. The group of trees is usually 11 to 24 inches dbh, and the highest densities of nests are within stands of 40 to 70% crown closure.

Source: Craig Grother, Wildlife Biologist
Norwood and Ouray Ranger Districts
Grand Mesa, Uncompahgre, Gunnison NF


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			The Abert’s squirrel *(Sciurus aberti)* is restricted to the ponderosa pine forests of the Colorado Plateau and southern Rocky Mountains of Colorado, Utah, Arizona and New Mexico in the United States and the Sierra Madre Occidental of Chihuahua and Durango in Mexico. The GMUG National Forest is located well within the range of this species. Most of the known populations are found on the Uncompahgre Plateau and Naturita Division of the Uncompahgre National Forest. The Abert’s squirrel is dependent upon ponderosa pine for food, cover and nest sites. Preferred habitats are composed of all-aged ponderosa pine stands with trees in even-aged groups. Abert’s squirrels are active throughout the year. Their diet shifts with the seasons and availability of food. They consume the seeds, inner bark, terminal buds and staminate flowers of ponderosa pine along with Gambel oak acorns, fleshy fungi, carrion, bones and antler. The most nutritious food source is the seed of the ovulate cones, which are produced by mature trees. The availability of pine seed varies widely since cone crops vary markedly from year to year. The inner bark of subterminal twigs is a reliable source of food that is used primarily in the winter and spring of the year. Abert’s squirrels seem to select certain trees (feed trees) for their quality of twig growth, apparently based on tree vigor. Fungi are the primary food source in summer and fall. Squirrels feed on a variety of mushrooms and particularly seek out hypogeous fungi found growing in association with ponderosa pine tree roots. These mycorrhizal associations are primarily associated with dense canopy stands of black jack pine with deep layers of needle duff. Abert’s squirrel nests have been studied extensively, and several relationships have been described for cover requirements for nesting. The most important components are tree density, diameter and a grouped distribution of trees. Nests are located in the upper limbs of a tree that is situated within a group of 3 to 5 trees with interlocking crowns. The group of trees is usually 11 to 24 inches dbh, and the highest densities of nests are within stands of 40 to 70% crown closure. Source: Craig Grother, Wildlife Biologist Norwood and Ouray Ranger Districts Grand Mesa, Uncompahgre, Gunnison NF