BIGHORN SHEEP: CHARACTERISTICS, HABITAT, FEEDING - BIOLOGY - 2025

The bighorn sheep (Ovis canadensis) is an artiodactyl belonging to the Bovidae family. This species has huge horns that characterize it. In males, they can weigh up to 14 kilograms and grow downward and forward. As for those of the females, they are small and thin.

This bone structure is used by males in the collisions they make between them, to establish dominance in the group. Also, due to their anatomical and morphological characteristics, they protect the brain from impacts.

Bighorn calf. Source: Carlos R. Marrero Reiley. Own authorship

In addition to the horns, the cranial bony septa and the large frontal and cornual sinuses help to protect the encephalic mass. This is achieved because they offer resistance to shocks and absorb the energy that the bighorn calf receives at the head.

State of conservation

Bighorn sheep populations have declined in recent years. However, IUCN studies consider this species of least concern.

However, the international organization considers it necessary to apply the pertinent actions so that Ovis canadensis does not become part of the group of animals in serious danger of becoming extinct.

-Threats

Risk of fatal epizootics

The fragmentation of the habitat restricts the movements of this animal and causes it to concentrate in small areas. In this way, the spread of some pathogens increases.

Livestock diseases pose a serious threat to bighorn sheep, especially in areas where several species interact.

Genetic diversity

The probable loss of genetic variability is a problem in isolated herds. These small groups depend on interactions with other sheep to maintain the viability of the population.

Experts suggest that decreased heterozygosity and inbreeding influence disease resistance, antler growth, and survival rate.

Habitat degradation

The loss of the natural environment of the bighorn sheep is due to forest fires and the use of the land for livestock and urban planning purposes. In addition, this fragmentation blocks the migratory corridors that exist in the habitat and the dispersal routes. This could lead to the isolation of populations.

Disturbance of space by human activities

In many areas, Ovis canadensis has become habituated to human activity. However, the use of snowmobiles in winter represents a risk for these animals.

Likewise, it is also made up of mineral exploration and extraction activities and low flight of aircraft.

Competition

In the regions it inhabits, the bighorn sheep often compete with livestock for water, space, and forage. This situation originated, in the early twentieth century, a notable decrease in the density and composition of the plant community in these areas, causing a decline in the population of Ovis canadensis.

Hunting

One of the main threats is illegal hunting. Since the early 1900s, the capture of this animal has been prohibited in several countries and in others it has been regulated. However, this practice continues to be carried out today.

Their horns are the trophy of this activity, which affects the entire population, since it eliminates the breeding males from the herd.

-Conservation actions

In Canada, more than 4,500 bighorn sheep are protected within the Rocky Mountain National Parks. However, in these areas they are vulnerable to poaching, due to the presence of man and they are easy to distinguish in this environment.

In relation to the United States, it is found in 30 Wildlife Refuges. Some of these are the Grand Canyon in Arizona, Death Valley in California and Yellowstone in Montana.

This species, in Mexico, is included in Appendix II of CITES. In that country it is protected in the Sea of ​​Cortez, in the Isla Tiburon Wildlife Reserve, where there is a population that was successfully introduced.

In addition, it is in the Sierra de San Pedro Mártir National Park, in Baja California, where there are mountain forests that serve as a refuge for numerous species.

Habitat and distribution

The distribution of Ovis canadensis covers the western region of Canada and the United States and northern Mexico. In Canada, it is located along the Rocky Mountains in British Columbia and in Alberta. It is also south, from the Peace River to the US border.

In relation to its location in the United States, it is found from Idaho and Montana, to the south, and the northern area of ​​Utah, to New Mexico and Colorado. In Mexico, the bighorn sheep previously lived in Nuevo León, Chihuahua, Coahuila, Baja California, Sonora and Baja California del Sur.

However, it currently only inhabits northeast Sonora, Baja California, Tiburon Island, the Sea of ​​Cortez, and Baja California Sur.

Habitat

This species usually inhabits mountain slopes, deserts, alpine meadows, and hills near steep, rocky cliffs. Likewise, it lives in open grasslands, coniferous forests, deciduous forests, and shrub steppes.

During the winter season they are between 762 and 1524 meters high, while, in summer, the range is between 1830 and 2590 meters.

There are some environmental components that are important for the bighorn sheep to develop. These include water, escape terrain, and forage.

The availability of an escape territory allows the survival of the animal. This is because, before an attack by coyotes or wolves, it can flee quickly, climbing the rocky ledges.

Access to plant species is a determining factor in the selection of the land. In this way, it can generate seasonal migrations, in search of plants with a high quality of nutrients.

However, during the breeding season, the female obviates this pattern, to move to areas that provide more security for the offspring, against possible attacks by predators.

Feeding

The desert sheep, as this species is also known, feeds on the plants that are available in each season. Within the range of plant species available, it prefers those succulent and with high quality of nutrients.

In this way, the diet varies in each region. Thus, in west Texas the preferred species are the ocotillo and the sotol. In the desert areas, nopal and date fruits predominate.

Female bighorn calf. Source: Carlos R. Marrero Reiley. Own authorship

Palatability is another factor considered by Ovis canadensis for food selection. An example of this occurs with mugwort. In Montana, the diet of this animal is based 43% on this shrub. In contrast, in British Columbia, mugwort consumption only accounts for 1% of the diet.

The differences in this use could be due to the essential oils that make up this plant species and their flavor.

The diet includes grasses, reeds, grasses and shrubs. As for water, they obtain it, for the most part, from the moisture contained in the vegetation. However, they usually drink it from rivers, streams and lakes.

Species

The bighorn sheep consumes a wide range of grasses, among which are Poa spp., Agropyron spp., Bromus spp. and Festuca spp. These species are consumed almost all year round, because they constitute an important reserve of nutrients.

Also, its diet is made up, among others, by Phlox spp., Potentilla spp., Linnaea americana, Trifolium spp., Atriplex hymenelytra, Tidestromia oblongifolia and Encelia spp.

Reproduction

The production of eggs and sperm begins around 18 months; however, sexual maturity is reached between 2.5 and 2.6 years of age. There are several factors that influence the beginning of the reproductive stage, among which are physical development and environmental conditions.

This is why, due to the competition between males for mating and the hierarchy based on size and age, males usually mate at 7 years of age.

In the female, estrus lasts approximately two days. Some species mate for 1 to 2 months before mating. In this way, dominance relationships are established and reinforced. Males with the largest horns tend to dominate the group and copulate with several females.

However, near the end of the heat, subadult males may have a high probability of mating.

Mating and gestation

The bighorn sheep performs various behaviors within the courtship phase. In males, the first sign of activity is when they move among the females, approaching from behind to smell their genitals. In addition, they raise their lips, to detect odors with the vomeronasal organ.

Also, they can kick them with one of their forelimbs and lift the body into a pre-mount position. For her part, the female actively corresponds to this courtship, even riding it, to try to get their attention.

The gestation period lasts for approximately 175 days, after which a single calf is usually born. The female looks for a steep region to give birth. In this way, it protects the baby from predators and the harsh environment.

Breeding

Alan D. Wilson

The baby of the Ovis canadensis is precocious, when it is born it is already standing and an hour later it begins to walk. Before one day, she travels with the mother to nearby areas. In the next 2 weeks, the young eat grass and are weaned between 3 and 7 months of age.

Behavior

Hierarchy

Before the start of the mating season, bighorn sheep establish a hierarchy of dominance. The intention of this is to create a leadership that determines, among other things, access to females for reproduction.

In this behavior, two males, who are far apart, run to get closer. They then face each other, standing up on their hind legs and loudly bumping their horns. The winner will be the leader of the pack.

As for the females, they have a non-linear and stable hierarchy, correlated with age. When they are between one and two years old, they may strive for high social status within the group.

Social

Ovis canadensis is gregarious, being able to gather in herds of more than 100 animals. However, small groups of 8 to 10 sheep are more frequent. Generally, adult males are kept separate from females and young, forming a group of singles.

Young females remain in the same group as the mother, which is led by the older female. The young males leave the herd when they are around 2 to 4 years old, to join the other young.

References

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