O. dalli live in mountainous alpine habitats distributed across northwestern British Columbia, the Yukon, Northwest Territories and Alaska.

Complete colour intergradation occurs in both O. dalli sheep subspecies (i.e., Dall's and Stone's), ranging between white and dark morphs of the species.

[4] Current taxonomy using mitochondrial DNA information may be less reliable due to hybridization between O. dalli and O. canadensis recorded in evolutionary history.

[3] Current genetics analyses using a genomewide set of single nucleotide polymorphisms (SNPs) has confirmed new subspecies range boundaries for both Dall's and Stone's sheep, updating the previous pelage-based and mitochondrial DNA classifications.

They are off-white in color, and their coat consists of a fine wool undercoat and stiff, long, and hollow guard hairs.

O. dalli are found in areas with a combination of dry alpine tundra, meadows, and steep or rugged ground.

During spring and summer, ewes are more likely to select areas such as steep, rocky slopes with lower predation risk to raise offspring.

[10][11] Social order and dominance rank is maintained in ram groups through a variety of behaviors including head-on collisions.

Other behaviors associated with establishing social order include leg kicks, bluff charges, and dominance mounting.

Most of this behavior establishes order year-round, but clashes between males with similar horn sizes intensify as the rut approaches.

Consequently, subsistence harvest of O. dalli is lower now than in the 1940s, but sheep continue to be an important meat source when caribou migration routes shift during the winter or between years.

[12] Where sport hunting is allowed in Alaska's national preserves, hunters can harvest mature O. dalli rams that have horns that are full-curl or greater, have both tips broken off or are eight years of age or older.

Changes may include shifts in locations of plant communities (e.g., an increase in shrubs in alpine areas), diversity of plant species (e.g., loss of important forage species for sheep), and local weather patterns (such as increased incidence of high winter snowfall and icing events), which may affect sheep distribution and abundance.

Warming climate trends, longer growing seasons, and changes in precipitation have the potential to allow woody plant species to find suitable habitat at higher elevations.

Changes in the seasonal availability and diversity of alpine plants may affect O. dalli populations by altering sheep diets and consequently where they can live in mountain parks, as well as ewe pregnancy rates and lamb growth and survival.