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:
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.
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.
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.
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)