Rocky Mountain Elk (Cervus elaphus nelsoni)
Taxonomy
Kingdom: Animalia
Phylum: Cordata
Class: Mammalia
Order: Artiodactyla
Family: Cervidae
Genus: Cervus
Species: Cervus elaphus
Subspecies: Cervus elaphus nelsoni
Conservation Status in Idaho
Least Concern
Range and Habitat
Within North America Rocky Mountain elk can be found in the Rocky Mountains and adjacent ranges of western United States and Canada. During the summer elk are found in subalpine forests and alpine basins. They migrate to lower elevations, open forests and floodplain marshes in the winter. Elk prefer open woodlands, coniferous swamps, clear cuts, aspen-hardwood forests and coniferous-hardwood forests.
There are four extant subspecies of elk found in North America. The Roosevelt elk (C. elaphus Roosevelt) is the largest and ranges along the Pacific coast from northern California to Washington and Canada. The Rocky Mountain elk is the second largest elk subspecies which Idaho has the third largest population behind Montana and Colorado. The Manitoba elk (C. elaphus manitobensis) are found primarily in the provincial and national parks of Manitoba and eastern Saskatchewan however they were once found along the eastern edge of the Rocky Mountains through Colorado. The smallest subspecies, tule elk (C. elaphus nannodes) once roamed the valleys of northern and central California and are now managed by state and federal agencies on California public land.
Physical Features
Weight: Males 700 lbs (318kg); Females 500lbs (227kg)
Shoulder Length: Males 5ft (1.5m); Females 4.5ft (1.3m)
Body Length: Males 8ft (2.4m); Females 6.5ft (2m)
Antler Length: up to 4ft (1.2m)
Antler Weight: up to 40lbs (18kg)
Elk are one of the largest members of the Cervidae family. Elk have a dark reddish hue during the summer and a lighter grayish hue in the winter. Elk also have clearly defined buff colored rumps and small tail. During winter elk grow thicker hair and a thin neck mane that shed by early summer. Only bull (male) elk have antlers. Antlers are shed in early spring and grow throughout the summer. While actively growing antlers are covered by velvet, a highly vascularized soft layer of skin. Velvet is shed once the antlers are fully developed.
Diet
Elk are primarily grazers, feeding on native grasses supplementing on forbs and tree sprouts in the summer and tree bark in the winter.
Lifespan
Elk live up to 15 years in the wild and 20 or more years in captivity.
Reproduction
The mating period for elk begins in early September and typically runs for 10-12 weeks. The period is known as the rut where mature bull (male) elk compete for and defend a group of cows (female) called a harem. Female elk are sexually mature at age two and have a short estrus cycle, 1-2 days. Gestation is 240-262 days usually single birth with calves weighing 35 lbs. The calves are spotted when born. Calves are fully weened by two months and will remain with their mother for nearly one year.
Social Behavior and Interaction
Elk are gregarious and remain in herds throughout the year. Herds are not consistently composed of the same individuals. Habitat, predators, forage, population density, breeding activities and weather influence herd patterns. Cow groups however tend to be more cohesive than bull groups. The largest groups tend to form in winter and early spring. During the spring migratory elk will disperse into smaller groups as they reach intermediate elevations and yearling and 2-year-old males tend to leave joining bull groups once calving starts. In the fall individual herds begin to form large herds for rut which then break into smaller groups as male seek out and defend cow groups or harems.
Major Threats
The primary threat to elk is hunting and predation. Other sources include diseases, parasites and malnutrition due to weather conditions, food supply and food quality. Primary predators include American black bear, grizzly bear, cougar, gray wolves and coyotes.