Sierra Nevada Bighorn Sheep - Habitat and Behaviors

Habitat and Behaviors

Sierra Nevada bighorn sheep inhabit portions of the Sierra Nevada located along the eastern boundary of California in Tuolumne, Mono, Fresno, Inyo, and Tulare Counties. Habitat occurs from the eastern base of the range as low as 4,790 feet (1,460 m) to peaks above 14,100 feet (4,300 m). Sierra Nevada bighorn sheep inhabit open areas where the land is rocky, sparsely vegetated, and characterized by steep slopes and canyons. Wehausen provides a detailed description of Sierra Nevada bighorn sheep habitat throughout its range. They prefer open ground to better detect predators and allow enough time to reach steep, rocky terrain (escape habitat). Forests and thick brush are usually avoided if possible.

Most of the sheep live at higher elevations 10,000–14,000 feet (3,000–4,300 m) in subalpine and alpine areas during the summer. During winter, these sheep occupy high-elevation, windswept ridges and tend to prefer south-facing slopes where snow melts more readily or migrate to lower elevations (4,800 ft (1,500 m)) in sagebrush-steppe areas to avoid deep snow and to find forage.

Sierra Nevada bighorn sheep are gregarious, with group size and composition depending on gender and season. Spatial segregation by gender occurs outside of the mating season. Bighorn sheep ewes generally remain with the same band in which they were born. Males older than 2 years of age remain apart from females and younger males for most of the year. During the late fall and winter, the groups come together and concentrate in suitable winter habitat. Breeding takes place in late fall, generally November and December. Lambing occurs between late April and early July on safe, precipitous, rocky slopes; most lambs in the Sierra Nevada are born in May and June. Ewes and lambs often occupy steep terrain that provides a diversity of exposures and slopes for escape cover. The lifespan for both Sierra Nevada bighorn sheep males and females has been observed as 8 to 12 years.

Bighorn sheep are primarily diurnal. They are primarily grazers; however, they may browse woody vegetation at times. Plants consumed include various grasses, browse, and forbs, depending on season and location. Naturally occurring mineral licks provide necessary minerals for bone and muscle growth.