These unusual animals usually inhabit areas, dominated by Ponderosa pine trees that provide them with required nutrients. Abert's squirrels are identified by their long tufted ears, due to which the animals are sometimes called 'tassel-eared squirrels'. These mammals exhibit the ear tufts during most of the year. Mature individuals lose these tufts between July and September. Abert's squirrels have no fear of heights. When foraging, these animals are frequently observed moving between branches high in trees.
Abert's squirrels are distributed throughout the southwestern United States and the north central Mexico, where these animals occur in scattered populations. Thus, the United States hold 4 isolated populations of this species, two of which are considerably large, while the other two are small. In Mexico, Abert's squirrels are presented by two large but isolated populations. The ideal habitat of this species is mountainous areas, dominated by ponderosa pine tree. In the past, Abert's squirrels were mistakenly thought to be dependent on this tree. In fact, they just rely heavily on it.
Abert’s squirrels do not appear to be territorial. Usually, multiple individuals may share the same nest. Meanwhile, each individual can use more than a single nest. They are diurnal. Active period of the day starts just before sunrise, lasting until just before sunset. Living among ponderosa trees, these animals occur in large concentrations of 2 - 114 squirrels per square kilometer. They are solitary foragers, spending their daytime hours looking for food. No information is available on whether they have any hibernation or torpor habits. In the beginning of the breeding season, which occurs in spring months, these squirrels display a highly social behavior. During the rest of the year, they are typically less social. Abert's squirrels communicate with conspecifics through vocal, visual, touch, smell and taste. Vocalizations include characteristic high-pitched clucks, barks, screeches and squeals, which are easily distinguished from these of other squirrels.
Abert's squirrels are herbivores, they primarily feed upon certain parts of the ponderosa pine: during the warm season of the year, they consume seeds and buds of this tree, whereas the winter diet typically consists of the inner bark of the ponderosa pine. They are also known to supplement their usual diet with occasional mistletoe and fungi.
Abert’s squirrels are polygynandrous (promiscuous): this is when both males and females have multiple mates. During the mating season, males display aggressive behavior towards each other. A pack of males can follow a female through the forest for about 11 hours by day, led by the dominant male. Abert’s squirrels mate between late February and early June. Gestation period lasts for 43 days, yielding 1 - 5 babies with an average of 3 per litter. Newborn squirrels lack fur and come with closed eyes. Males of this species display no parental care except for guarding their mates after mating. At 7 weeks old, the young begin climbing down to the ground. Weaning occurs after 10 weeks old, whereas sexual maturity is reached by 11 months old.
In spite of being classified as Least Concern, this species is threatened by living in isolated populations, depending on the distribution of ponderosa pine. Another notable concern is habitat destruction by clear-cutting throughout large areas of their natural range.
According to IUCN, the Abert’s squirrel is widely distributed and abundant at some localities but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) and its numbers remain stable.
Due to relying on the ponderosa pines, these animals have hugely affected this tree, which is their main source of food and shelter. On the other hand, they have negatively affected Mount Graham red squirrels, inhabiting the Pinaleño Mountains (Arizona): Abert's squirrels were introduced to the habitat of endangered red squirrels, which consequently led to a harsh resource competition between these two species.