January 2014 | Observations of Horses Living Freely Provide Food for Thought
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Observations of Horses Living Freely Provide Food for Thought

January 2014 - Sue McDonnell, PhD, CAAB, Adjunct Professor and Founding Head of the Havemeyer Equine Behavior Lab at Penn Vet’s New Bolton Center

Fledgling harem band within New Bolton CenterThis fledgling harem band within New Bolton’s semi-feral herd was formed during the 2013 breeding season. Young stallion Skippy (left) stole the mature mare Gemini and her foal, Tin Man, from an established harem. Another young filly, Addy Walker, (right) left her natal band to join this newly formed family group seemingly of her own choice. (Courtesy, Havemeyer Equine Behavior Lab, New Bolton Center)

One of the most fascinating aspects of horses living under natural social and foraging conditions is that they do so well with so little, even in fairly inhospitable environments and climates. They thrive without all of the hoof care, dental care and other modern health-care and nutrition we provide our on-farm horses.

The hallmark of horses living freely in natural, mixed-gender and -age groups is that they seem to be fairly free of the many ailments, injuries, and behavior problems common among domestic horses. Gastrointestinal disorders are rare among free-living horses, as are limb-related lameness, hoof abscesses, and laminitis.  Social injuries are far less common – in spite of having multiple stallions, mares, foals, and yearlings all interacting enthusiastically – than for horses at pasture on most modern farms. 

Similarly, among free-running populations, the classic equine behavior problems –including cribbing, pacing, weaving, head tossing, and food-related aggression – are essentially non-existent. Fertility and fecundity of feral and semi-feral herds far exceed anything expected for our managed horses, even with the best modern veterinary reproductive care.

Many horse owners, veterinarians, and equine scientists have long recognized the health of our horses can be compromised by how we feed, house, group, and exercise them. Behavioral biologists, by carefully observing horses living freely, understand more fully the management choices that could be contributing factors.

Over the last decade there has been rapidly growing interest and modestly increasing support for research by equine behaviorists, exercise physiologists, and nutritional scientists. While we recognize that turning horses out to live and breed naturally is not a practical strategy, applied equine behaviorists are suggesting some simple management changes to incorporate more natural behavior. These changes can often overcome and prevent health problems, as well as improve the overall welfare of horses, while still meeting the needs of owners and trainers.

The following are ten observations of natural horse behavior derived from studying the semi-feral herd of small Shetland-type ponies at Penn Vet’s New Bolton Center, and incorporating research of other equine behaviorists from around the world.

  1. Move a lot. When living in natural social groups, horses move a lot.  Typical 24-hour movement during simple activities like grazing and trekking to water or shade totals at least 10 miles a day. When forage becomes sparse, more miles are accumulated finding adequate nutrition. Social interactions among foals, yearlings, bachelor stallions, harem stallions, and cycling and foaling mares adds considerable daily mileage. During the socially busy spring months, the accumulated miles can quickly multiply, particularly for harem stallions looking after their mares and foals, as well as bachelor stallions aiming to acquire a mare or two. Mares accumulate the lowest mileage, except for the weeks just before and after foaling. Modern GPS trackers have confirmed in several horse populations that activities can total nearly 100 miles in 24 hours. This continuous movement probably contributes to their overall health and fitness, as well as to their natural hoof wear.
  2. Move whenever eating. Grazing animals are always moving when they are ingesting food. Even when forage is abundant, they take a few bites, take a couple of steps, take a few bites, then more steps. This natural behavior may help food move through the digestive tract. Providing hay and feed in one location in the stall or paddock discourages movement while ingesting, which may lead to colic and other digestive disorders.
  3. Trickle feed. Horses have evolved in environments where the available forages were fairly low-calorie and high-fiber. Accordingly, their digestive system is adapted for continuous ingestion and throughput. Feeding our horses concentrated meals, more like carnivores and humans rather than like grazing animals, has long been known as a significant factor in gastrointestinal and behavior problems. These problems include gastric ulcers, colic, and bothersome behaviors such as cribbing, pacing, weaving, and food-related aggression. It’s no secret that if horses can be managed with continuous access to low- to medium-quality forage, with no calorie-dense grains and sweet feeds, the risk of these health and behavior problems can be reduced.
  4. Never stand still for long. When horses do stand still, it’s not for long.  Time at rest rarely exceeds an hour. In fact, after resting for no more than 20 to 40 minutes, they appear compelled to move, usually to resume foraging. This rhythm of alternating periods of eating and resting, with very fixed brief periods without movement, persists even in some stalled horses. Upon rising or stirring from a standing rest, stalled horses almost always return to eating or foraging as if looking for something to put in their bellies.
  5. Foals are precocious to the max. Birth is typically far faster and almost always easier on natural terrain and with the social support and protection of the stallion and other band members than in a foaling stall. Especially with the stallion present, foals are up and running far sooner, because a birth, along with the fetal fluids and membranes, puts the entire band at risk of attracting predators. Minutes after the foal is out, typically the stallion urges the mare and foal to get up and move away to a clean area. Once away from the fluids, the mare will then pass the membranes, and again the stallion moves them to another clean area for the foal’s first suckle and rest. This all can occur within the first 10 minutes. Soon after birth, the other foals, yearlings, and juveniles within the band, as well as in neighboring bands, stimulate the foal’s activities. In fact, foals born within a natural harem social environment are far more advanced in the early minutes and hours, and continue to develop behaviorally more rapidly than foals born into modern farm social conditions where they are isolated with just their dam or are pastured with only other mares and foals.
  6. Stallions are active parents. While the dam is the source of nutrition, under natural social conditions the harem stallion clearly does most of what we think of as parenting. Once the mare is again in foal, usually within a couple weeks, her primary compulsion seems to be grazing, as she supports her own nutrition, that of this year’s foal, and that of next year’s foal. She seems quite relieved to turn over the other parenting functions to the stallion and older siblings. The stallion not only takes over most of the protection and retrieval of wandering foals, but he also may instigate play behavior with foals and yearlings.
  7. Weaning is very gradual. Foals up to about six months of age are the most frequent to be observed nursing, but yearlings, two-year-olds, and even older offspring that have not left their natal band are typically welcome at the dam’s udder. Nursing by older offspring seems to serve a consoling function in the moments following a stressful or threatening event. As has been studied in other mammals, early or stressful separation from the dam leads to changes in the structure and neurochemistry of the brain that predispose the individual to later behavior disorders, including separation anxiety, panic disorders, and other neuroses analogous to some of the behavior problems of some domestic horses.
  8. Distance is the signal of submission. Under natural social and environmental conditions, injuries resulting from social interactions are very rare, and almost always minor, in spite of the numerous interactions among stallions, mares, and foals, with continuously evolving and changing social relationships. One clear factor is the ability to express submission by moving away, along with the absence of man-made objects to get in the way or trap animals from escape. Domestic horses often don’t have the ability to move away, and so can never “say uncle” and call a truce. On farms, injuries can be reduced through choices in paddock size and design, as well as feeding locations. Social aggression can often be reduced by taking into account the social order within the herd when deciding on the grouping and re-grouping of horses.
  9. Horses are slow and subtle to show fear or discomfort. Having evolved as a grazing, prey species on open plains, horses are “hard-wired” to be slow to show discomfort, especially in threatening situations. Their behavior has evolved not to show discomfort until it is very intense. Domestically managed horses tend to “mask” signs of disability, causing us to be slow to recognize pain or illness, or causing behavior changes that can be mistakenly attributed to misbehavior or poor temperament.
  10. Incest avoidance. Under natural conditions, every species has behavioral mechanisms to avoid inbreeding to ensure as much genetic diversity as possible. Mares breed and form lasting bonds with the most distantly related stallions that are available, and stallions actively avoid breeding their daughters or sisters even though they may still be with the natal band. While our domestic horses are considered promiscuous breeders – in other words, they will typically breed with any mate we offer – some of the incompatibilities or simple variation in enthusiasm seen in our human-arranged stallion and mare matings may be due to this natural incest- avoidance behavior.