Horse

## Description

The horse (Equus ferus caballus ) is a domesticated, odd-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of Equus ferus. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature, Eohippus, into the large, single-toed animal of today. Humans began domesticating horses around 4000 BC, and their domestication is believed to have been widespread by 3000 BC. Horses in the subspecies caballus are domesticated, although some domesticated populations live in the wild as feral horses. These feral populations are not true wild horses, as this term is used to describe horses that have never been domesticated. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior.

## Appearance

Horses are ungulates with an unguligrade foot posture, single-digit oval-shaped hooves, long tails, short hair, long slender legs, muscular and deep torso build, long thick necks, and large elongated heads. The mane is a region of coarse hairs, which extends along the dorsal side of the neck in both domestic and wild species. However, wild horses have a mane with short hairs that remain upright while domestic horses have longer mane hairs that do not remain upright. A mid-dorsal stripe, a dark stripe that extends from the mane to the tail, is sometimes present, especially in wild types. The teeth are specialized for grazing, with hypsodont cheekteeth. The dental formula is 3/3, 0-1/0-1, 3-4/3-4, and 3/3. Newborn horses have curly hairs and a finer mane than adults before molting and growing their winter coat. Winter coats start developing in September and October, are fully grown by December. They start shedding in the summer over a period of 56 days for adults or 75 days for newborns. Winter coats are typically thicker and the top of the tail usually develops a region of short hairs, forming a tuft.Domestication of horses has led to wide variation in the characteristics of breeds of horses. Coats vary in color, from white to black and including reds, browns, and yellows, as well as a wide variety of patterns, such as spots and pinto patterns. Size can vary depending on the breed and its intended use, but can range from 227 to 900 kg in mass and 0.9 to 1.7 meters in height, with potential outliers. Leg length, head length, body-build, fur color, metabolism, etc, varies across breeds of domestic horses. Despite the great variation in physical features within horses, they can generally be distinguished from other equids, by having longer manes and tails and generally a lack of zebra-type stripes.

## Distribution

Due to the domestication of Equus caballus, and its widespread distribution following domestication, the natural geographic range is typically considered the distribution in the Late Glacial period, 9,500-15,000 years ago. During this time, horses were widespread. Wild horse populations existed in the northern tip of Africa adjacent to the Tyrrhenian and Mediterranean Seas, across Europe excluding the most northern regions where the Scandinavian countries currently exist, and as far east in the Palearctic region as China and Mongolia. They extended throughout the northern Palearctic, across Beringia into the Yukon, and as far south in North America as Mexico, as far east as the Mississippi River, and as far west as the Pacific Ocean coastline. It is believed that the wild horses in North America went extinct 8,000 to 10,000 years ago. Domestic horses were then introduced into North America upon European colonization.

## Behavior

Horses are social mammals. In wild or feral populations they form herds with a social hierarchy. These herds, also known as bands, can have up to 26 mares, 5 stallions, and various ages of pre-dispersed young. Typical herd sizes will have only 5 to 11 mares and 1 to 4 stallions, in addition to their offspring, but these numbers vary among scholarly articles and may vary with food availability, environmental conditions, and other factors. This hierarchy is comprised of the alpha male being dominant over the herd, males dominant over females, females with young dominant over non-reproductive females, and adults being dominant over juveniles. The dominant or alpha male is significantly more active than other members of the herd. Studies show that, in feral horses, where regular members of the herd usually spend less than 10% of their time moving around, dominant males move from 25 to 45% of the time and sleep only 5 to 6% of their time, when the other herd members usually spend 20 to 27% of the time throughout the day sleeping. Alpha males also expend large amounts of energy rounding up females and defending them against other males during the breeding season. Alpha males usually move in the back of the herd, but will move to the front in the presence of a threat and signal to the herd in the event that the herd needs to flee. The alpha may also attack a threat if necessary to defend the herd. Horses are crepuscular and have an interrupted sleeping pattern that compliments this. During the summer, horses graze in morning or evenings to avoid mid-day high temperatures, and can be seen visiting water sources at night as well. To adapt to this feeding pattern, they sleep in segments throughout the day, which are usually not more than two hours long. They also avoid laying down for more than an hour at a time if possible, and can be seen sleeping while standing up.

## Diet

Primarily folivores by nature, horses primarily graze on true grasses. Domestic horses are often fed various amounts of grains, including oats, barley, corn, wheat, flax, soybeans, alfalfa, clover, Timothy hay, and Johnson grass. In addition to this diet, they may also be provided vitamin and mineral supplements. Feral horses eat a similar diet, including Russian thistle, dropseed grasses, mesquite, prairie junegrass, green sprangletop, and saltbush, and likely varies depending on location and season.

## Reproduction

The horse mating system is similar to that of other equids, which is a polygynous mating system. Males typically herd females during the mating season and defend them against other males, who may be trying to mate with the females. Males do not typically herd and mate with any of his daughters or any females that grew up with him in the same herd. Males fight with other males through kicking and biting, losers submit and retreat. This process is very energy intensive and similar to the rut seen in deer species. Hierarchy in herds is influences by reproductive status and age, with females and their newborn young getting first access to resources, followed by juveniles and non-reproductive females. Alpha males dominate access to resources.

## References

https://animalia.bio/horse

https://animaldiversity.org/accounts/Equus\_caballus/