How Do Horses Behave In Natural Herds?
Why do horses choose to live in herds?

Prey animals often live in herds because of the benefits of group living. Safety is the number one priority for equines so having the safety of others is an important feature of this. Increased vigilance occurs with more individuals to look out for danger. Herd members also enjoy a greater choice of play-mate and potential partners. The down-side of this is that a larger group of animals are more conspicuous to predators and the risk of certain diseases is higher. However, the benefits of group living far outweigh the risks.



Being heavily dependent on their senses, the primary alert response in horses is an elevated head and neck, with intense orientation of the eyes. Horses usually use binocular vision at these times, as well as their ears to assess for potential threats in their environment. This posture in one horse sets off a ripple effect in others. If a perceived threat is recognised as being dangerous, then horses will take flight to create distance between themselves and the threat. If it is a false alarm, older, more experienced horses will return to grazing within minutes and younger horses who may still feel uncertain, will eventually follow their lead. It can be costly for social living and an individual's physical and emotional health if horses are hyper-vigilant. These horses appear "over-reactive" and can find it hard to keep weight on. They may also be difficult to handle, but their behaviour is sadly not always recognised as having a basis of fear.

Groupings within a herd:

Feral populations of free roaming horses have shown that herd size often correlates with the availability or lack of resources within the environment. Larger herds may have to travel much greater distances to find enough food for all of the members, which can be costly.

A herd of horses usually consist of one or two bands that share the same home range and move as a group. A band usually consists of family members, including adult horses and their offspring. Within this grouping a breeding group is known as a harem. Horses employ a polygynous mating system, whereby a single stallion bonds with, protects and mates with several females.

Male foals disperse from the natal band (a band in which they were born), at approximately 1-2 years old and either create or join a bachelor herd. A bachelor herd is made up of non-breeding males. Bachelor herds allow young males extensive opportunities to play and hone skills that might be useful if they decide to bid for alpha status when they are older.

Herd personal space:

Feral populations have been observed living in groups of varying sizes, inhabiting areas that often have overlapping home ranges. A home range can vary in shape and is not defended as a territory because it is not exclusively used by one herd. Horses will become familiar with their home range and will know exactly where to find particular resources that are available during the season in which they use that area.

Within the home range is a core area. This may be a central area in which horses choose to spend a significant proportion of their time. Observations have not shown that these areas are exclusively used either. These contribute to other observations, which have seen stallions defend herds, not territory. Horses are incredibly adaptable, as is shown by the varying different habitats that feral groups populate. They live on islands, open plains, deserts, and mountains and yet despite this, few domesticated horses have truly adapted and live healthily in traditional domestic settings because they so often compromise their basic needs.

What are "normal" behaviours?

Observations of free-ranging horses have provided an enormous amount of information on horse behaviour per se. It is the careful application of this information that has, for some horses, revolutionised their management. This is because owners have been able to create opportunities for domestic horses to fulfill their most basic fundamental equine needs whilst living within the constraints of a domestic environment.

The Equine Ethogram is a species-specific list of "normal" behaviours that give us insight into a horse's behavioural needs. Generally horses will only perform behaviours that are necessary for their survival. By knowing what behaviours are "normal" we are able to identify abnormal behaviours. Abnormal behaviours occur because a horse is unable to perform the behaviours within its ethogram.

These normal behaviours include:
  • Living in a permanent, mixed sex herd, with unlimited access to all individuals.

    Domestic consideration - Single sex grouping only allows same sex relationships and individual turn-out paddocks do not allow horses to establish and maintain social relationships. Stallions are often kept in social isolation, which is a significant welfare compromise. Whilst I appreciate that it is not always practical for stallions to run with a herd, this would allow them to establish an attachment with the mare and allow them to have an active role in parenting.

    Herd dynamics can change rapidly if a horse is sold on, his familiar herd will have a gap in their social hierarchy and he will often, suddenly, find himself in a new herd, which adds to the trauma of changing ownership or moving yards.

  • To have unlimited access to their preferred companion(s). Horses often show a preference for particular members within their herd.

    This attachment is apparent due to how much time they spend together whenever they have the opportunity to be in the same space. They will sleep, groom and play together as well.



    Domestic consideration - This special attachment may be challenged each time your horse's preferred companion is taken to be ridden, or even when they are separated to be stabled overnight, not to mention if they are taken away for the day/weekend to compete or if the horse moves to a different yard or for whatever reason, if the horse dies.

  • To have normal sleep patterns. (This will only occur if they are in a permanent herd and have the safety of others to keep watch while they sleep.)

    Horses are polyphasic, which means that they sleep for very short periods of time across their day. Time sleeping equates to approximately 15% of their day, which means that they are awake for 85% of the time. Their sleep time is divided into dozing stood up or lying on their sternum. Horses can only experience REM (Rapid Eye Movement - often referred to as dream sleep), sleep whilst lying flat-out.

    Domestic consideration - Some stables are too small to allow horses to lie down. This can lead to chronic tiredness, which impacts all other aspects of your horse's life. Some horses feel too fearful to lie down and others may be experiencing pain, which prevents them from being able to get down and/or back up again. It has been found that some stabled horses sleep for longer because there is often little else to do. Increased sleeping is also a sign of depression in humans, so it is important to consider this for animals too.

  • Being able to explore their environment, e.g. knowing where to find a water supply and where to shelter from the weather.

    Horses that are familiar with their environment know where to go to find particular resources. They know where the best vegetation is, where to find shade, where to roll. They also know the boundaries of the fence line.



    Domestic consideration - Horses that move yards frequently can find it extremely difficult to ever become completely familiar with their environment. Even changing fields on the same farm can compromise your horse's safety need, so care needs to be taken when introducing them to a new environment.

  • To have 24 hr access to grass/forage, allowing them to eat forage for up to 16 hours a day.

    Horses are herbivores, like many other domestic animals, but they are not ruminants. They only have a single stomach and their food digestion takes place in the caecum, which is found at the end of the large intestine. Horses have evolved to have a low protein and high fibre diet, which involves high volume of food intake that passes quickly through the digestive tract. It is also fundamental that a horse can move around freely whilst eating.



    Domestic consideration - Horses have evolved to survive on forage-based diets. In fact, the forage can actually be quite poor in quality. Many horse pastures are former dairy cattle grazing which can be incredibly dangerous for horses prone to laminitis or those with Equine Metabolic Syndrome. Not to mention that many become obese on these pastures. In contrast to this, few stabled horses are fed ad lib forage. This means that many spend the majority of the time in their stable feeling hungry. This will impact on their physical and emotional health and has been linked to aggressive behaviour. Horses fed with hay-nets become frustrated, have to have their head in virtually the opposite position to grazing and generally stand in one position whilst they eat.

    During winter, even horses that might be turned out, will not always be offered hay in the field. Without an understanding of your herd's social hierarchy and Resource Holding Potential contests (see below), it can be dangerous to put a limited amount of hay out and this is why many people decide not to put hay in the field. Instead, if you spread hay piles out, (this can be done before any horses are turned out), ensuring that there are more hay piles than horses, this will make sure that horses are able to eat safely and keep warm, without feeling that they have to defend their hay pile.

    Hard feed, fed from buckets often provide a horse with the majority of his daily recommended allowance in one go. Buckets deny the horse the opportunity to forage and move whilst eating. This causes frustration and is the reason that many horses paw the ground or paw the air with a fore leg whilst eating their meals. Provided that there are no medications in the feed, it is useful to scatter it onto the floor so that your horse is able to take their time to forage and move and eat whilst doing so.

  • To have unlimited access to trees and hedges so that they can browse on. (This behaviour has evolved from millions of years ago when the horse was the size of a fox and lived in forests.)



    Domestic consideration - Many owners are surprised to find out that their horses need to eat certain leaves and strip bark from logs. They will also browse on hedgerows if given the opportunity to. Although wood chewing can occur through boredom (which is an indicator that their environment needs enriching), it could also start because of a desire to fulfil this basic need and/or increase their fibre intake.

    J.A. Allen have published a book on plants and trees that are poisonous to horses so please consult this or similar before feeding any to your horses. Willow, poplar, ash and oak (logs only for oak) are safe types.

  • To be able to play with herd members. (Horses will only feel safe enough to play if they are familiar with herd members.)

    Equine play patterns are innate, this means that they are born with them. Some play is solitary for example object-play, which involves the use of an object such as stone or a twig found within the natural environment or a brush or ball which are objects that can be introduced to the horse safely. Other play patterns are social and involve initiating play that is motion based such as running or other interactive games such as nipping.



    Colts naturally play more than fillies and this usually continues into adulthood. Male horses also spend more time on particular types of games such as play mounting and nipping as these skills form part of their repertoire for later life. Mares are more likely to participate in motion games such as running.

    Domestic consideration - Play is vital for physical and emotional wellbeing for each individual and for social cohesion between herd members. This can only occur when horses are familiar with each other and therefore predictable. Single sex grouping does not allow horses to experience all kinds of play and individual turn out and stabling does not allow any kind of social play to occur. To improve our horses' welfare we must allow them access to perform these behaviours daily. When a horse is unable to, they are more likely to become susceptible to illness and problem behaviours can occur.

In addition to the equine ethogram, behavioural scientists have recognised that within the finite period of a 24 hour day, horses have prioritised certain behaviours that need to be performed in order to achieve physical and emotional wellbeing. These are defined as "Maintenance Behaviours" and are species-specific. They are made up from behaviours that feature within the equine ethogram. Thinking this way, it becomes easier to view problem behaviours as the "tip of the iceberg", occurring because basic maintenance behaviours are not being met.

A common example that many are likely to have witnessed or experienced is the horse that becomes fearful when a particular companion is removed from the field. He may not be able to graze or drink because his safety need has been compromised. This may be demonstrated by running the fence line, or standing quietly by the gate. Sequentially, he is unlikely to prioritise rolling and stretching, which makes it highly unlikely that he would choose that time to rest and sleep. In fact quite the opposite is likely to happen.

Separation anxiety/distress can show itself in many ways, but all arise from a horse's evolutionary need to have equine company and the fear they experience when on their own or even within their herd, but without the company of a particular companion.



Carpenter (1980): Equine priority of needs - behaviours that help maintain physical and emotional health

Who makes decisions for the herd?

Thankfully, many of us have moved away from the notion that it is a stallion that leads a herd. Horses live in small families, groups of bachelors and small mixed sex groups of young horses. Family groups focus around one or more adult females. Any group member can make a decision to change activity, and if others are suitably motivated, they will follow suit. As such horses are followers rather than leaders in their day to day activities. For example, a nursing mare will become thirsty sooner and more often so may frequently be seen leading movement to water. Just like all the best matriarchs she is a security figure for the herd, and few will want to lose her from view, adding to the motivation to follow. Equine behaviour scientist, Konstanze Krueger has demonstrated that younger, horses pay attention to senior horses in learning tasks, but not vice versa. Further evidence for the important roles older and wiser horses play in equine society.

Best friends

As well as being offered protection by the whole herd, each horse will often have an extra special friend to eat, play and groom with. Typically horses will form strong attachments with another horse of the same gender, height and age, because it does not have a reproductive basis. The biological drive to establish and maintain this kind of attachment is so strong that if another horse is not available, a horse will select the next best thing, which may even be a different species. This highlights how important affiliation is in order to feel safe as a prey animal.

These kinds of attachments can develop within weeks of birth and may last a lifetime without human interference. Unfortunately, owners can find it frustrating when their horse becomes "too" attached to another in the field and this is one of the reasons given for using individual turn out paddocks. But of course this kind of relationship has massive evolutionary significance.

Social Etiquette

Another misnomer is that equine social systems are linear, by this I mean that there is an animal at the top of the social hierarchy and each member follows sequentially to the very bottom. The animal at the bottom is the "under-dog" (sorry cross-species term there.....) and this animal has little or no social standing.

Behaviourists studying feral populations and domestic herds have recognised that equine social systems are far more complex than that. More importantly they have identified some fundamental factors, which account for where an animal may find themselves in that social system.

How a social structure is established and maintained depends largely on the social interactions that occur between group members. These may include cooperation, competition, submission or even dominant behaviour towards each other in order to acquire particular resources such as food, water, shelter, mating partner. These contests are called Resource Holding Potential Contests (RHP).

Each horse will contest with another horse as to whether it is dominant for an individual resource on a one-to-one basis. They do this by using body language and facial expression to communicate for others to come closer or move away. Physical contact is rarely needed. The horse that "loses", defers by offering their submission and the "winner" is the dominant horse. Once a relationship is established with a particular herd member a horse will begin a contest with a different horse. This continues until all members have either won or conceded in a contest. From this the social hierarchy is established. Generally when resources are plentiful and within a permanent herd there will be very few contests occurring. If however the resource is very valuable or in limited supply, e.g. during winter months when grass is low and hay piles becomes more valuable, then a horse might continue to contest when before he may have deferred. Each time a new horse joins the herd, social stability will be disrupted as all members have to re-establish their positions. Preparation for such RHP contests begins at an early age with safe play sequences. These improve coordination and athleticism and also establish and maintain social relationships between herd members.

Those with the highest RHP are particularly aware of the need for herd cohesion and will strive for this by sharing resources amongst herd members.

In conclusion, domestic horses can meet their fundamental needs, including living in a natural herd but it can take some careful planning and consideration. It is absolutely crucial to acknowledge and strive for herd cohesion by creating opportunities for horses to form safe, permanent relationships and by being creative in allowing them to fulfil the behaviours within their ethogram.

References

Mill,s D. & McDonnell, S. (2005) The domestic horse. The evololution, development and management of its behaviour. Cambridge UK.

McGreevy, P. (2004) Equine Behaviour, A guide for Veterinarians and Equine Scientists. Saunders, UK.

Worthington, M.K., Horse watch, what it is to be equine. (2005) J A Allen, London.

McDonnell, S. (2003) The equid ethogram: A practical field guide to horse behaviour. Eclipse press. London.

Copyright Kelly Taylor of Solace Training (Animal Behaviour)