UNDERSTANDING THE LANGUAGE OF THE HORSE A PILOT STUDY: 'THE EQUINE SEMAPHORE CODE (TESC)

The Equine Semaphore Code - the horse talks back, created with expansion of The Equine Semaphore Code by Meljay Turner.

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The Research



UNDERSTANDING THE LANGUAGE OF THE HORSE A PILOT STUDY: 'THE EQUINE SEMAPHORE CODE (TESC) - AN ETHOGRAM OF THE HORSES EAR MOVEMENTS.

PART 1: IDENTIFYING THE 'AT REST' EAR POSITION.


AUTHORS

Turner*, M., Young, K., and Pearce, J.

6th April 2019

A project submitted in partial fulfilment of the requirements for the Bachelor of Science Degree in Animal Management/EquineManagement BSc Equine Sports Therapy and Rehabilitation, for the University of Greenwich.




PROJECT DECLARATION FORM

ACADEMIC SESSION: 2016-2017

PROJECT DECLARATION


“This project report is the result of the independent work of Meljay Turner*. All other work reported in the text has been attributed to the original authors and is fully referenced in the text, and listed in the Reference Section”.

Student Name:- Meljay Turner -

Student Signature:-



Date:- 23rd April 2019



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ACKNOWLEDGEMENTS

Kim Young - Supervisor to the project.

Jennifer Pearce - Statistical advisor

Emm


a Thorne Centre - substitute project supervisor - Manage Greenwich Equestrian Centre

Rachael Tolfery - substitute dissertation equine lecturer

Suzanne Edwards - Radlet Student Support

Jacob Knight, for excellent knowledge and assistance in using the Library resources. Sonja Wilkes, head of equestrian at Hadlow College.

University of Greenwich for the continuing support and opportunity to explore the language of the horse


.


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ABSTRACT

To date, an in-depth study of the equine communication system based on the ears has not been documented, this is the first study to claim this, with general studies focusing on aspects such as pain (Dyson et al., 2018; Gleerup et al., 2015). ‘Facial Ac


tion Codes’ have been applied to the expressions of the horse, including static ear action codes (Wathan et al., 2015), however, all studies overlook the aspect of potential communication in the variations of ear movements, and reasons for those variations.



The aim of this pilot study was to develop and expand current knowledge of horse ear actions, creating an ethogram - The Equine Semaphore Code (TESC), which identifies a clear gap in the standardisation and scientific efficacy of current understanding.


Using an established herd of horses of mixed breeds and sexes (n=8), video recordings were obtained of the horses at rest for 720 seconds (12 minutes), without human interaction. Applying the eth


ogram TESC - a coding system based on angle increments of 10° from a lateral view and frontal view, collating how many positions were presented. The results show that the variations of ear positions mentioned in current studies may have greater significance. By looking to identify the ‘at rest’ ear position, it has revealed connections to other actions of the horse and their connection to actions of the ears.




The study identified that the current understanding of ‘ears back’ or ‘at rest’ is subjective, and that an angle can be applied to calculate an exact ear position. Applying TESC in further studies focusing on all data, would be required for greater understanding both with, and without human interactions.


Keywords: equine, horse, communication, language, behaviour, welfare, training, ears, equiFACS, non-verbal.

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Contents details removed to save page space.

INTRODUCTION


Language of other species has been of fascination to the human animal for many years (Balter, 2010). With documentation as to certain species such as chimpanzees (Parr et al., 2007), and the calls of birds (Balter, 2010) have been featured in many documentations and journals. In more recent years, horses (Dyson et al., 2018; Mullard et al., 2017; Gleerup et al., 2015; Wathan et al., 2015; McGreevy et al., 2009), dogs (Waller et al., 2013), and cats (Caeiro et al., 2017), have been assigned a Facial Action Coding System (FACS) (Ekman et al., 2002) based on human expressions.

In previous studies connected to the horse in order to understand how they express themselves, focus has been on facial expressions, cognitive thinking analysis and behaviour patterns (Wathan and McComb, 2014). One aspect studies do not include fully in their analysis is that of the horse's ears with a common thread being that if the horse's ears are forwards they are alert, if they are back then this is a warning (Wathan and McComb, 2014). However, in comparing the images of the studies, the descriptors vary for the same ear positions. This pilot study introduces a new method of measuring the ear positions based on degree of angles, providing a scientific method to analyse the ear actions. Also identifying the variations of the commonly termed at rest ear position, and potential reason for the variations.





The ears are the one part of the anatomy of the horse that can be viewed from all angles, including if the horse has a long forelock (Wathan et al., 2015) especially the apex of the ears as shown in Fig.1, where 7 horses are standing together. This makes the ears a suitable study area to create and develop a new ethogram system based just on the ears: 'The Equine Semaphore Code (TESC)' detailed in Fig.2, observing how horses use their ears in communication in greater detail.




Relevance of how the data is collected is of utmost importance to achieve a baseline that is accurate. This is a factor that has not been considered in previous studies, as shown later in the literature review, and a possible failing of many of the studies presented to obtain accurate calculations. Taking a natural observation method of collecting data, as in studies of wild horses have shown that it is necessary to observe the horses in their natural environment, in order to identify a clearly defined communication system. White paper documents (Ransom and Cade, 2009) give a pattern of what is expected, showing observation without interference, rather than handling the horses during studies. Removing the human element has been put in to practice with collecting data to generate TESC, with part 1 giving a baseline and identifying of the variations of the horse's ear movements whilst at rest, and visual actions that precede the changes in the variations that were observed.


During the study it identified that the current head neck position (HNP) found in Elgersma et al., (2010), is not suited to the global population of horses due to its multiple measuring points and was redefined during this study.



HYPOTHESIS

It is hypothesized that horses have a language they use between themselves, and the ears as part of that communication or language system, which have greater meaning than currently understood.

It is hypothesized that there is no specific at rest ear position.

The null hypothesis is that horses have a language they use between themselves, and the ears are not part of that, except for the currently understood meanings.

The null hypothesis is horse have one at rest ear position.




LITERATURE REVIEW

Why look at the equine language?

Psychology of horses has been looked at for many years, aiming to gain an understanding of the mood of the horse, and its behaviour in the working environment (Randle et al., 2017). Yet studies acknowledge they still fail to recognise the language of the horse, and their communication often goes unnoticed by humans (Brubaker and Udell, 2016; Schmelzer, 2003). With modern handling of horses changing over the years, be it due to the admiration of the horse, human ethics changing, or seeing the horse in a different light other than just for work or meat (McIlwraith and Rollin, 2011), the need for studies that expand our comprehension of the equine language, will create an increase in appreciating the ways of the horse. Increased understanding will help reduce misunderstanding between horse and handler, breaking down communication barriers that currently result in unwanted horse and human behaviours (Goodwin et al., 2009).


In the review of literature, it was clear that there is currently no scientific element or standardisation to identify clear ear actions, with studies and books researching the horse's communication system not looking beyond the ear position as being static or set at fixed positions that relate to general moods. In studies ears pinned back as an action, lack descriptors of potential reasons of other body movements prior to the ears changing (Smith et al., 2018; Dyson, 2015; McGreevy, 2015; Smiet et al.,2014; Seaman et al., 2002; Miller, 1995). Although ears back generally connected with conflict or aggressive behaviour (McGreevy, 2015; Smiet et al.,2014; Seaman et al., 2002; Miller, 1995; Miller, 1995) the overall view is looked at and not individual actions of the horse. Looking at the behaviour of Przewalski horses, Bourjade et al., (2009) where it gives only one mention to the horse's ears, when a stallion was moving his herd, in that the ears were laid back with the head being low. Although this study gave HNP descriptors, there was no further mention of the ears. Within just these two studies there are two different descriptors that could potentially mean the same thing, the ears were back. Comparing a photograph in the Smiet et al., (2014) study of a horse displaying aggressive behaviour, however, the image showed the ears as facing backwards but not pinned to the neck, and no descriptive reference was made to this position within the study to ascertain if it related to the behaviour, although detailing that the horse was aggressive, with the ears not in the traditionally understood pinned back location, the descriptors of the ears were left out the writings.


Looking closely at the aspect relating to the horses' ears, and how they use them more extensively in communicating than has previously been understood, may be a key to expanding that knowledge (Wathan et al., 2015). Studies are making comments that there may be meaning behind the actions (Wathan and McComb, 2014), with descriptions of the ears moving constantly within studies (Wilsie, 2018), or rotating (Dyson et al., 2018a). With further studies identifying and applying descriptor codes to certain static ear positions (Wathan et al., 2015), however, they lack explanation and clarification of the meaning behind the positions.


Further investigations have shown the actions of the ears in a back motion may not be relate to anger, but with concentration, with the comparison connected to when humans are in deep concentration, they frown like that of anger (Wilsie, 2018). Whilst earlier studies in the 1980's concluded the ears had a vital role in how horses communicate with each other, many unexplained variations of the ears gives a basis for the continued research into the equine language and behaviour (Wolski, 1984; Heffner and Heffner, 1983 ) as quoted in (Warren-Smith et al., 2007), especially the full actions of the ears (Hall et al., 2014). The research is dated, showing a gap in time where no consideration has been given to the horse’s language until more recently.


One of the criteria for a grimace scale in the study by (Costa et al., 2014) detailed the ears as being stiffly backwards as part of the pain identification units. The images shown however, resemble the ears back at the same angle of the horse standing at rest position. In the results table, this ear position was not allocated a score due to the variations seen. The images present within this study also described the variations 'stiffly backwards', however on reviewing the images the ears are in an upright position with the opening to the ear facing outwards (Fig.3). The angle that the camera was focused on the horse’s head makes it difficult to ascertain a lateral or frontal view of the horse’s ears.




Fig 3. (Costa et al., 2014) Position of a horse's ears whilst in pain after castration.


The horse’s eyes communicating.

Expanding the knowledge for understanding the equine communication system, it has been detailed that horses use their eyes in other ways, displaying fear - shown by the widening of the eyes along with widening of the nostrils to increase the sense of smell (Frith, 2009). Eye gaze has been identified and used in descriptors for animals (Waller et al., 2017), in which direction can target an object with accuracy, showing a keen awareness of objects and surroundings. In comparison to human's disgust can be shown with a narrowing of the eyes and nose wrinkles, which causes the nostrils to reduce, narrowing the smell receptors (Frith, 2009). Eye gaze with studies however, have still remained uncategorised, with suggestions of potential meanings as in the Gleerup and Lindegaard (2015) pain study, where applying a tourniquet to the horse, it was noted the horses eyes glazed over into a constant stare, which then relaxed after a short time period, the still image shows a horse with neck band and cross tied, unable to completely freely move away from the pain as if in flight, however, free enough to move within the constraints of the cross ties, which also raises the question as to why horse stood still and took the pain without trying to move away from it.


Communication between species.


The FACs descriptors used for humans, have also been applied to animals with ethograms (Waller et al., 2017; Parr et al., 2007), including horses in which equine facial recognition ethograms have been produced (Wathan et al., 2015). This indicates the interest in the learning of how animals communicate to be of scientific value, but also the similarities despite the variations in species. In looking closer at the potential similarities between the human animal and non-human animal, lies a potential answer to how all animals communicate together.


Animals require a communication system for their survival (Pearson, 2008). For example, showing where the water hole is, where they last left the good bit of land they were grazing from and when there could be potential danger. Books indicate there is a social communication between horses (Draaisma, 2018; Wilsie, 2018; Schmelzer, 2003) however, it has not been detailed in scientific studies that communication goes beyond just their basic needs for survival, nor referenced that any consideration to this should be investigated in future studies.


An ethogram of the horse's ears.


This study focuses on an element of the ear position that is currently understood as 'at rest', however an at rest ear position has not been identified in studies. The elements have already been partially identified in the Wathan et al., (2015) study, but only in the context of an ear action being in a fixed position, but not in relation to isolated group actions. An ethogram code to the 'at rest' ear position was not assigned due to the variations, which has opened an area to focus this study.


Like any language, there must be structure for that language. In humans, (Frith, 2009) concluded that human facial expressions can be a very sophisticated communication system, for example the eyebrow flash is an indication of intention to communicate, and that eyebrow height is associated with perceived trustworthiness, or eyebrows that slop lower down the nose be untrustworthy (Frith, 2009). With the FACs facial coding system being applied to create the equiFACs ethogram, in horses it has been documented they raise their brows, like humans (Wathan et al., 2015), however, no meaning has been applied to the action of the raised eyebrow, nor if it is indicated as a form of communication.


Psychology of horses' moods are considered, with just one factor being taken for each ear expression, be it the ears pinned back, the ears forward, or the ear in a relaxed position at rest, or the ears flopping out to the side (Wilsie, 2018). There has been increased literature on understanding the facial expressions of the horse, mainly related to pain, with the study focusing on facial movements around the eyes and mouth (Wathan and McComb, 2014), however, there is no scientific research relating to the possibility that all these facial expressions along with the ear movements, are part of a complex language that the horse uses in its everyday life. The impact on the welfare of the horse if the human counterpart had a greater understanding of what the horse is communicating, would create a greater working partnership with potential to reduce behaviour issues. With the use of horses increasing, including assistance therapy methods for human support systems, it is important that studies continue to create a greater understanding of the equine communication system, to safeguard both the horse and handler (Randle, 2016).


It has been stated that the mobility of the ears has been overlooked in past studies, with focuses on just the head and eyes and the direction they are looking (Wathan and McComb, 2014). Others connect movement of the ears with the detection of sound, or where the attention of the horse is (Draaisma, 2018). Focusing on the images in Draaisma (2018), in Fig 4. it is noted that the horse detailed in Fig. A2.6 has the ears out to both sides potential listening, but also noted that this ear position is visible when sleeping, in pain and in times of learned helplessness, and depression. Considering for this image the camera handler is in front of the horse for the caption, once again if the ears are directed to the attention of the handler, the ears of the horse should have been towards the camera person. Fig. A2.3 from Draaisma (2018) looks very similar to Fig. A2.6, be it one taken from behind the horse and one in front.





The book by Draaisma (2018) continues to contradicts itself not within the writing, but within the images, with Fig. A2.2 (As detailed below in Fig.5) in the appendix it described the horse having one ear back and one ear forwards due to the handler's positions, in that that one handler is to the side of the horse, and one to the fore of the horse, with the claim that where the ears pointed, was where the horses attention was. However, in Fig 5.16 (as detailed below in Fig.5) of their study a similar scenario where a tractor, rather than a human, was in front of the horse with still the handler was behind the horse, the horse has both ears focused forwards on the tractor, and not one on the tractor and one on the handler. If the description of Fig. A2.2 (as detailed below in Fig.5) was correct, then the descriptor for the ears should have been the same when the horse had the tractor in front with the handler to the rear, in that the horse’s ears should have been on both the tractor and the handler behind. In Fig. 5.16 (as detailed below in Fig.5) the description of the ears at both being forwards was not mentioned and remained without comment, making the views of the observers subjective to what they were focused on at the time for the other areas of their study. These writings are not alone in the discrepancy between the words and the images portrayed.



The importance of identifying language.


Scientific research into animal communication first began to be documented in the early 1950s, aiming to understand the origins of language (Balter, 2010), but focused mainly on wild animals in captivity with perceived intelligence, such as Chimpanzee Facial Action Coding System (ChimpFACS) (Parr et al., 2007), OrangFACs (Caeiro et al., 2012), in these studies the focus is on non-human interference to document facial actions between the species. In a study by (Ransom et al., 2010) it states ‘examining behaviour ecology of equids can aid their conservation for wild herds', but also aid in management of captive horses. The (Ransom et al., 2010) notes the importance that it is critical that we deepen our knowledge of understanding equids, which will aid in providing more effective management of domesticated horses, reducing stereotypical behaviour. Further research by (Hall and Heleski, 2017) support the need for detailed ethograms that are universal for a greater understanding of the horse, and the relationship between horse and rider, potentially reducing conflict between the two. Emphasising the importance for clear and precise descriptions.


Current data collection methods for assessing horses.


Studies have shown the use of high-speed cameras and programs have been used to analyse the movements of the horse assessing body and gait patterns (Randle et al., 2017; Weeren and Crevier-Denoix 2006), aiming for increased performance, or identification of lameness (Dyson et al., 2018a). Digital technology is also used in studies focused on monitoring heart rate or hormones produced in conjunction to behaviours of horses, and although valuable to know and understand that hormones and heart rate impacts the behaviour of the horse (Ijichi et al., 2018; Baragli et al., 2017; Guidi et al., 2016). Using high speed digital technology would be a way forwards to capturing and studying the movement of the horse’s ears for more accurate analysis, as still photography and screen grabs analysis is insufficient, when it comes to documenting variations of frequent movement.


It has been confirmed in studies, that both the eyes and ears are essential to communicate intention (Wathan and McComb, 2014), yet the ears are still overlooked in studies. With the advancement of technology, it is now possible to fully utilise this, capturing the patterns of the movements that horses have in their communication system, in order to obtain a greater understanding.



Current knowledge

General terms of the horse’s ear positions are basic as show in Fig 6. Ears back, ears pinned, ears alert, ears out to the side, one ear back and one ear forwards.




When considering the ears of the horse, the descriptors placed in studies are all reliant on the reader having prior anatomical knowledge and understanding as to the described ear positions. It was not determined in the review of literature where these terms originated from and seemed to be a generally understood interpretation of the ear descriptors within the equine world as opposed to scientific research. Other non-common terms used, as described below, may involve an element of anthropomorphism (Randle et al., 2017). This creates a potential for misunderstanding with subjective evaluation of each horse and scenario.


Descriptor examples of the horses’ ears.


Descriptors of ear positions vary with Górecka-Bruzda et al., (2015) describes the ears lying flat against the head during a dressage study, whereas, Hausberger and Muller (2002) also use the term laid back as a descriptor for the horses’ ears when looking at a handler. Within a Dyson (2015) study, it refers to the ears being pinned back, whereas in her following study refers to the ears as laid back, however, the scenarios were similar (Dyson, 2016). Ears not being held back was used to assess if a horse was in pain prior to a riding assessment to ensure the horse was suitable to ride (Dyson et al., 2018b). This raises questions as to what each of the observers is seeing and if they are in fact the same angles, not all the studies have images, so description is left to the understanding of the reader.


Ears forward are used as ear descriptors in many journals and books (Wilsie, 2018; Draaisma, 2018; Dyson, 2018b; Mullard et al., 2017; McGreevy, 2015; Wathan et al., 2015; Smiet et al., 2014; Hausberger and Muller, 2002). However, when looking at the images, if they are provided, there is a variation to the angles seen. Different descriptors have been added to some journals such as, 'Ear Play' (Smiet et al., 2014), allocating a percentage of the time the ears moved as ear play, however, the position of the ears was described as ears forwards for this element.


Moving ears are detailed in many studies, Dyson et al., (2018b) describes in the ethogram for the ridden horse as the ears oscillating, which could be interpreted as ear play. Considering ear play could be classed at anthropomorphism, with human traits of movement signifying play (Randle et al., 2017), which can also be seen in books connected with horse language wording such as 'perky ears' or 'sideways ears' (Wilsie, 2018). Applying the equiFACs code, Wathan et al., (2015) connected variations with codes taken from their S41 Video, ear descriptors EAD103 (ear flattener), with EAD104 (ear rotator), followed by an action of EAD103 alone were identified as complete actions or isolated actions of ear movements. These descriptions, however, have little or no meaning to exactly what is happening with scientific value in the studies.


A further example in Waller et al., (2017) described in their study the effect of the facial coding action AU101 identified in humans as a sad face, in which certain dogs within rescue centres also displayed this expression when being visited for potential re-homing (Ekman et al., 2002). It was found this expression in dogs was a contributing factor as to whether dogs were re-homed more quickly, with the perception that the dog was sad (Ekman et al., 2002). By applying human emotion to the expressions as descriptors, invalidates the scientific value of the study.


In a study by Lesimple et al., (2011) looking at the learning ability of horses, housing impacts and handler safety, only once were the ears mentioned, but not with a descriptor. The study describes the head position and ears as 'high' and 'vigilant', again placing anthropomorphism on the actions of one returning victorious from war, or winning a competition (Lesimple et al., 2011). Looking into behaviour studies connected with horses, descriptors become less with assumptions that the reader would understand behaviour patterns such as head threat, and standing alert as mentioned in Benhajali et al (2008). These studies clarify the aim of this study, that without an accurate calculation or measurement, the meaning is subjective and open to interpretation.


Isolated group actions are identified in further behavioural studies, potentially demonstrating a communication system using the ears. The horse’s ear positions always being described as forwards or backwards (Wilsie, 2018; Smiet et al., 2014; McGreevy, 2015; Hausberger and Muller, 2002), or rotated backwards (Dyson and Van Dijk, 2018). However, Dyson (2018) details horses holding ears back and moving ears between upright, forwards and to the side connecting the movement actions of the ears. In another study by Dyson and Van Dijk (2018) as the ears rotating backwards, demonstrating the ears movement from one position to the next and not a static position. This is confirmed in a further study by Mullard et al., (2017) that identified the ears to have ‘divergent actions’, showing the individuality of each ear. Showing that studies are recognising more is present with the actions of the horse's ears, however, the studies do not provide a method to analyse these actions in order to obtain understanding.


It was in a study by Jankunis and Whishaw (2013) that identified an ear action that has not yet been assigned an action code, this was in connection to taste bud test and behaviour with horses, in which it was identified the ears in a forward motion, but with a more rostral angle than upright. It was identified that the head was relaxed in HNP1 as based on the current HNP ethogram (Elgersma et al., 2010; Nestadt et al., 2015), and although 2 images within the Jankunis and Whishaw (2013) study showed actions of the ears, an ethogram code was not assigned to this finding. This reiterates that from studies and books that there is no defined calculated angle or position of the ears, which leaves descriptions of ear positions open to interpretation based on the understanding and knowledge of the reader.


Looking at the studies by Elgersma et al., (2010) and Nestadt et al., (2015) connected with the HNP’s described, however, there is unreliability in the method of measuring the head neck position. Seven HNP have been identified in studies (Nestadt et al., 2015; Smiet et al., 2014; Elgersma et al., 2010), however it is noted that measurements have been made from several different areas of the horse for each alignment from the angle of the withers (see appendix 2), connected with the withers either the front of the face, or the jaw line of the horse, which would not provide an accurate figure when applied to a global population of horses, especially if taken from the jaw line of the horse, all horses have different shape and size jaws, not all horses have flat faces, and if base on the withers this would not be accurate for overweight horses, or different breeds that have a higher crest of neck, such as stallions. A constant feature for all horses would be required for a global population head neck position, in order to ascertain a correct ear position.


Comparing images of the horse in the Wathan et al., (2015) study, Fig 7, in which the ear description is considered as neutral, and the Draaisma (2018) study in Fig 4 above, the resting ear position is consider sideways pointing caudally, however both horses within these studies are described as being at rest, and are shown to be laying down. Demonstrating the differences between understandings to the ear actions.





Other animals in research


In the more recent years, it has been noted that animals have a communication system that is understood by multi species. Chimpanzees have been recognised for having a language based on using the Facial Action Coding System (FACS)(Parr et al., 2007). The study by Parr et al., (2007) into facial expressions and language with chimpanzees showed that FACS could be applied to non-human primates and set a precedence for observing without human interference to create a ChimpFACS coding system. Ear Descriptors have been identified in catsFACs (Caeiro et al., 2017), DogFACs (Waller et al., 2017), OrangFACS (Caeiro et al., 2012), and ChimpFACs (Parr et al., 2007) as part of the communication system. These seem to be the basis for applying them to horses in the Wathan et al., (2015) study, whilst Proctor and Carder (2014) identified 4 ear positions in cows assigning them a code as E1, E2, E3 and E4, however, they did not use a FACs system. In a further study connected to cow ears, the same E1, E2, E3, and E4 codes were used, however, it was noted that description for E1 detailed more than one ear position, being its pinna facing forwards or laterally on a vertical line (Lambert and Carder, 2019). In a study by Rius et al., (2018) found possible connection with the ears of pigs being associated with the emotions of pigs. These studies draw the attention to a common purpose, in that there seems to be a need to identify a greater understanding of the animal communication system, in order to benefit the animals.

Removing the human element


Feral horses are good subjects to understand the way they naturally communicate with each other and studies have been done on behaviour of feral herds (Hartmann et al., 2012; Kimura, 1998). Removing the human element from the study, which provides the opportunity to observe natural behaviour without interference, was shown to observe a greater understanding between the relationship of the animals, and their natural way of behaving (Kimura, 1998). Use of technology with management of horses has increased the more advanced it has become, providing benefits of remote digital recording technology, in which animals can be observed in their natural environments without disruption of humans (Randle et al, 2017). A necessary aspect for observing any species for a complete understanding.


In studies, and books, there always appears to be an element of human interaction with the horses, be it they are in close proximity to record on their devices, or the horses are held by a handler , which could have affected the results of the ear positions (Caeiro et al., 2017; Waller et al., 2017; Wathan et al., 2015; Proctor and Carder, 2014; Caeiro et al., 2012; Parr et al., 2007). If a base understanding of natural behaviour is not fully understood, adding additional elements such as human presence will affect the results, with too many variables, which has been shown to influence the way in which the animals respond as documented in a study by (Proops and McComb, 2012) in which cross-modal recognition of handlers of horses combine both sound and vision to their identification process; horses were found to respond quicker to their owner's voice than that of a stranger. This is confirmed in studies showing that horses not only use facial expressions, but can also understand human facial expressions, even from someone they have never met before (Smith et al., 2016). With having a human present in the (Wathan et al., 2015) study, the variations of ear positions seen for the 'at rest' ear position may have been influenced by the closeness of the camera handler, and/or who was taking the footage.


In expansion of this, a study connected with the sounds horses respond to involved, which detailed ear positions when connected with certain sounds, there were humans and speakers in front of the horse, and to the side of the horse the human was wearing headphones with sounds playing in them (Smith et al., 2018), these create too many variables such as the horse hearing the sounds in the headphones, and the humans making facial expression that the horse could interpret, as to an accurate study making the study counterproductive (Randle, et al., 2017). It has been noted in studies with other animal studies, there is always detailed an element human involvement (Lambert and Carder, 2019; Caeiro et al., 2017; Waller et al., 2017; Wathan et al., 2015; Proctor and Carder, 2014; Caeiro et al., 2012; Proops and McComb, 2012; Parr et al., 2007). It is only with removing the human element, can an accurate baseline be acquired as to how horses use their ears for sound, communication and behaviour.


Muscle anatomy of the horse’s ear.


Studies and books only give some details as to the ear muscles in the horse, with focus for studies being the inner ear for hearing disorders. This makes understanding the function of the ear muscles incomplete to calculate the many actions the horse’s ears can perform. (Wathan et al, 2015) detailed the difficulty of obtaining all muscle details due to the head of the horse being severed at the wrong place interfering with full results.


Ear anatomy, the origins and insertion of the ear's musculature need to be clearly identified for observations of other possible head actions that may alter the ear position. Many of the books and journals that do mention ear muscles seem to be incomplete or have assigned different names to potentially the same muscle (Wathan et al., 2015; Kainer,1993; Goody, 1976). The dissection by Wathan et al., (2015) identified a thin flat muscle positioned subcutaneously above the temporalis and found no reference to this in the search for ear muscles. However, no name was assigned to this muscle. Its origin identified at the zygomatic arch, the parietal and frontal crests, with insertion at the scutiform cartilage.


In describing the outer ear, the external part of the horse’s ears is generally shaped the same, except for Marwari and Kathiawari horses, where the apex of the auricle is curled medially (Prajapati and Belsare, 2017). The ear has a range of motion of 180 degrees (Kainer,1993), and can move on two sagittal horizontal planes (Gleerup et al., 2015). The ear is covered with short hairs, which are thinner than the hairs to the face and neck (Kainer,1993). With long protective hairs emitting from the conchal of the ear canal.


Journals and books connected with anatomy and ears seem limited, with the focus being on the inner ear and not the muscles of the horse’s ear, however none provide a comprehensive catalogue of descriptors with origins, insertions and actions. In the dissection performed by Wathan (et al., 2015) describes the Scutuloauriculartis profundus, with 2 muscle group of a major and minor muscle considered the strongest muscles in the ear, measuring 25mm wide, however, does not describe the function of these muscles. Kainer (1993) details the Scutuloauriculartis profundus the caudal auricular muscles detailing the precision of the insertion to the auricle. Whereas Goody (1976) describes the Scutuloauriculartis profundus as the middle auricular as the abductor of the conchal, and distal auricular as the levator of the conchal, creating two different muscles actions for the Scutuloauriculartis profundus. Wathan (et al., 2015) and Kainer (1993) do not agree on the origins of these muscles, one stating from the nuchal ligament (Kainer, 1993), and the other stating from the scutiform cartilage (Wathan et al., 2015). The impact of the movement of the ear would vary greatly with the differences of these origins. The most informative book by Sisson et al., (1975) based most of its information on a much older book dated 1911 by Sission, providing more descriptions and additional ear muscles than understood in the 1911 book. However, this book may also be incomplete, where the focus in the book was based on the nerves and arteries around the ears, and not the ear muscle structure or the actions of the ears.


The zygomaticus muscle may possibly have a connection with the ear actions with the origin to the fascia covering the masseter and buccinator muscles, with the insertion to the corner of lip (Wathan et al, 2015). Observed horses during a study connected with dressage, that the ear movements of the horse changed as more pressure was applied to the bit, raising questions as to the understanding of the equine head anatomy and the full effects of the actions of the facial muscles on the ears (Ludewig et al., 2013). The action of the zygomaticus to retract the angle of the mouth, placing pressure on the fascia, this may indicate that mouth action maybe connected with ear movements.


PROCEDURES AND METHODOLOGIES.


Using an established herd of horses of mixed breeds and sexes (n=8), video recordings were obtained of the horses over a two-week period with the horses of 168 minutes, with the horses in various natural habits. Of the 168 minutes, 12 minutes (720 seconds) of video footage was extracted and analysed to create a baseline of the horse’s ear positions at rest, without human interaction.


The reason for this chosen herd is the length of time they have been established, and that he horses are in a non-ridden environment with minimal interaction with humans. The horses are free to move around as a herd, in a 6-acre field that was set up as a grass track system at the time of recording. Based at (((((Details Removed))) Kent. Within the herd is one family unit, Sire; Piebald Gypsy Cob (colt at adding to sanctuary, gelded on arrival), Dam (pregnant at date arrived at the sanctuary); Welsh B pure bred Palomino/Dun mare. Producing offspring during time at the sanctuary; a Skewbald mare, Welsh B x Gypsy Cob (age 3 at time of study). The remainder of the horses have come to the sanctuary as rescues, or those with behaviour issues requiring a permanent home. The target population mean age is 8.4 ±5. The herd have been established and growing since 2012, with last additions to the herd in April 2017.


The data collected was unscripted and relied on the natural behaviour of the horse (Ransom and Cade, 2009; Kimura, 1998).


The paddock was set up as an electric track system, with smaller grazing areas in the centre of the field. Hay feeders are at 100 metres away from the watering area. The horses have a daily diet of ad libitum mixed seeded hay, one small feed in the morning for medications or supplements. The pasture contains a mixture of bushes and plants ‘herbs for forage; Rosehip, Hawthorne, Bayleaf, Marigolds, Lavender, Plantain, Parsley, Garlic and Field Maple. Total length of the track is 500 metres (see appendix 1).


A camera – DSLR Cannon 1300D was used to record the footage capacities of 50 fps, suited for slow motion extraction of the ear movements, and connected actions.

A 500mm zoom lens (Cannon) to record data without interfering with the natural behaviour of the horses.

A 3-legged tripod, unbranded.

Video recording was obtained using a VauxKimura, 1998

Frontera 4x4 as a shelter for observation without human interference. The Frontera was a constant feature in the paddock, and the horses are were habituated to its presence prior to the study.


The camera handler and camera were set up prior to recording taking place, for a familiarisation period in order not to interfere with the process of the horse being recorded. The horses were recorded once they had settled into a full rest pattern.


Maximum video recording footage was captured without interruption of 720 seconds (12 minutes), before the camera automatically ended recording.


Microsoft Windows Video editing software with slow motion capability to isolate ear movements. Using a Vostro15, 3000 Series DELL Laptop. With Microsoft Snipping Tool, to grab still images from the video, with inbuilt protractor to measure the angles of the ears.


Microsoft Excel for collated data analysis.


Statistical data acquired through SPSS, with a Friedmans test for normality, and Wilcoxen to establish



Activities


One chosen activity to measure the ear positions, with the horses at rest, as defined in the (Ransom and Cade, 2009). Where the horses were shown to be resting in a group with one hind leg resting on the toe of the hoof, or were laying down.




The method behind the ethogram - The Equine Semaphore Code


A new method analysing the ears was created, based on the position of the apex of the ear. Previous observations in books rely on the complete ear, where the whole ear was measured to determine length of ears (McGreevy,2015), however, the apex of the ear is visible from all angles hence a new measuring system was designed. The apex of the ear being clearest part of the pinna that is visible above the poll and can be observed from all around the horse (see appendix 3 of footage of horse standing still to demonstrate). The aim to create a new template for measuring the angles of the ears from both a lateral view and frontal view in order to ascertain more accurate position of the ears.


The new ethogram for the horse's ears 'The Equine Semaphore Code (TESC)'. Based on angles of the ears from a lateral and frontal view (Fig.8), providing a basis for future studies. Marker points from a frontal view are in line with the sagittal markers for the lateral view, from each side of the head. Four marked areas, (Fig. 8), demonstrates the marker points that must be used for TESC to function fully – (1) the tip of the apex of the ear, (2) the distal part of the apex of the ear for the guideline to sit, (3) the cranial/distal base of the ear, and (4) the centre point from a frontal view, connecting the sagittal lines from ear to ear points. These marker points are used irrelevant of the horses HNP, always keeping a horizontal line through the sagittal planes between markers 3 and 4.




Applying the ethogram TESC - a coding system based on angle increments of 10° from a lateral view and frontal view, collating how many positions were presented. An example of the code in action in as the horse in this image became alert to a car driving down the road, (Fig.9) identifies the alert ear position, coded as - TESC=OS(i)8-2(0). (Offside, upper sagittal line, 80° -2° cranially, zero signifying that a frontal view was not visible.)





Explanation - The Equine Semaphore Code


This new ethogram method assigns each ear a code both cranial and laterally. Alphabetically from a frontal view along the sagittal line A - H. Roman numerals along the two height levels along the rostral sagittal line (i) - upper level, and (ii) -lower level. Numerically for the lateral view 1-19.

The breakdown of the code for duplication can be seen in Fig.2, showing from a ‘frontal view’, from the centre point of the horse face, along the sagittal lines. Be it upper or lower dependant on the horse’s ear level at the time of measuring. The horizontal lines base lateral part of the ear (i) and Lower drop zone (ii) or sagittal lines, based on studies showing horses ears drop lower when in pain (Gleerup et al., 2015). The marker points for both frontal and lateral view is cranially at the distal base of the ear. The vertical line matching the medial plane of the horse's face.


For the frontal view, the degree of angles is labelled as A-H, (A=80°, B=70°, C=60°, D=50°, E=40°, F=30°, G=20°, H=10°) for each ear, offside and near side. This would create a frontal code of - ‘offside, (i) sagittal line, 50°, zero showing no lateral view, shown as code - TESC=(OS(i)(D)(0))


The Lateral view the degree of angles labelled as 1-19 angles with 90° being the switch over point between cranial (1=10°, 2=20°, 3=30°, 4=40°, 5=50°, 6=60, 7=70°, 8=80°, 9=90°), and caudal (10=80°, 11=70°, 12=60°, 13=50°, 14=40°, 15=30°, 16=20°, 17=10°, 18=0°, and 19=,-10°).


The horizontal lines upper sagittal line (i) and lower sagittal line (ii), re

mains always to its marker points between markers 3 and 4, irrelevant of the head neck position.

The results of each ear position from a frontal view being labelled: TESC=(OS(i)A(0)) - (offside, 80 upright angle, upper level, A, zero showing a lateral view is not visible), or nearside ear TESC=(NS(ii)D(0)) (nearside, lower level, D, zero showing a lateral view is not visible). It would need to be stated if the ear is facing forward or backwards to clarify direction of the opening, levels A and B can be cranially or caudally due to the horse’s ability to flip its ear between the two in an upright manner.


From a lateral view they would be labelled TESC=(OS(i)5(0)) (a cranial angle of 50° degrees cranially, on the upper level, zero signifying a frontal view is not visible), TESC=(OS(i)13(0)) (a caudal angle of 50° degrees, on the upper level, with no frontal view), and so forth. As an example, Fig.10 details a forward ear position.




Fig. 10 Example of Cranial ear position TESC=(OS(i)6-4(0)) (Authors own image)

The basis of angle measuring system, is preparing for future studies to obtain a more accurate understanding of the horses' ears, and their method of using them to communicate. Defining the variations of the different ear positions (Wathan et al., 2015).


Redefining the head neck position measurements.


Head Neck Positions (HNP) are detailed in studies (Elgersmaet al., 2010; Nestadt et al., 2015), however, there is no constant variable as to the deciding factor of the calculations as shown in the review of literature. In order to create a HNP that could be applied to all horse breeds, and allow for TESC to be consistent, a new HNP was devised – The Equine Semaphore Code Head Neck Position (TESC/HNP). This new method being based on the angles of the horse's superior lacrimal punctum, with the eye being a constant feature in all horses except where injury, or deformity has occurred. The horse's orbital socket is made up of 3bone plates - Frontal bone, zygomatic bone, lacrimal bone which creates a vertical structured line to the fore of the horse’s eye (Fritz, 2012). This area of the horse is constant across breeds, making it a suitable marker to measure for the angles of the head.


Around these connect the eye muscles creating the shape to the eye. In Fig HNP-1, showing 3 different breeds of horse, it is visible that the shape of the eye is consistent across breeds when comparing photographs of mixed horses, irrelevant of the shape of the horses face or jawline.




Fig. HNP-1 – TESC/HNP -Angles of the horses' eyes, demonstrating different breed types do not affect the eye structure. Bottom left image shows the horse iris looking forwards which changes the orbital aspect of the eye muscles. (Authors own image)




Fig. HNP-2 The Equine Semaphore Code Head Neck Position (TESC/HNP), a visual on how the angles work to ascertain head position. (Authors own image).


Explaining Fig. HNP-2, the measurement process is based on left and right angles with centre point at the corner of the eye, followed to the red dot marker making it in line with the bone structure of the eye socket, and creating a 90° angle no matter where the horses head is positioned. From a offside view if the nose moves in a dorsal direction the tilt of the red dot moves to a positive (+) marker. If the nose moves ventral to the chest, the red dot moves to a negative (-) marker.

Using current studies (Elgersma et al., 2010; Nestadt et al., 2015), it was identified that from the Head Neck Positions (HNP) that HNP1, based on the angle of the eye, is at an exact angle of 90° using the new measurement of the TESC/HNP. Creating the HNP1 from studies, in the new code as TESC/HNP(n=0).


In Fig. HNP-2 the second picture code would look like TESC/HNP(n= +5) Indicating an dorsal movement. Within the two side images a ventral action creates a negative code, as TESC/HNP(n= -6.4) indicating a 64° angle. With the lower image TESC/HNP(n= -5.4) a 54° angle, potentially showing a difference between the actual flexion being applied to the horses neck, due to the shape of the horses head being different.


In applying the TESC/HNP to this study a set format was used to identify ear positions using TESC.









RESULTS


The study was be carried out over the course of 2 weeks, with initial recording of 163 minutes of video recording, taken over 24 video sessions, with the horses in 5 chosen activities to measure the ear positions; the horses entering a grazing area they only had limited access to, the horses grazing together, horses at rest, the horses around the water buckets, and the horses eating around a hay feeder. Of the video footage, only 12 minutes was decided to use with the horses at rest, due to the amount of data collected it was required to be reduced, the focus to identify a potential at rest ear position as a control study for future studies.


Access to feral horses was not available for this study, however, Paddock Sanctuary keep their non ridden mixed herd of mares and geldings freely with only minimal human interactions for maintenance and welfare, which provided a suitable alternative for natural observation. Using technology to remove the human element (Kimura, 1997; Randle et al., 2017)

One horse remained isolated from the main groups as defined as 3 body lengths distance (Benhajali et al, (2008). The remainder of the herd followed a similar pattern as shown in Fig.11, with horses 1 and 2 standing together, with an isolated gap between horses 3,4 and 5. Then a further isolated gap between these 3 horses and horses 6 and 7. It was noted that the horses separated according to colours, horses 1 and 2 grey and palomino/dun, 3,4 and 5 coloureds, 6 and 6 – chestnuts, and horse 8 a blue roan (not visible in Fig.11).




Fig.11 Group horses resting divided off into colours (Authors own image).

The study identified 245 ear changes in 43 groups of movement (see appendix 4) groups being defined as areas of activity between inactivity. A time of 162 of the 720 seconds were assigned to these activity groups. Each ear change had a preceding body action, such as foot movement, tail swish, yawn, laying down as shown in Table 1 (see appendix 5). Applying the new ethogram TESC, 12 different lateral ear positions were observed -TESC 3-14, as detailed in Fig.12.

A Friedman's one-way ANOVA performed in (SPSS, 2019) rejected the null hypothesis of ’one at rest’ ear position (p<0.01). With a Wilcoxen 2-way related samples in (SPSS, 2019) identified TESC 7, 8, 9, 10, and 11 as predominately used (p<0.02).


Fig.12 Total all horse ear actions, showing range from 3 through to 14 of the TESC ethogram. (Authors own image).



DISCUSSION

It has long been understood that horses are very intelligent, patient and kind creatures. During war times, it was understood that horses knew to survive they had to stand still with their handler (Bethell,1861). How the horse understood this, may have related to the horse’s ability to read the expressions on the humans faces (Smith et al., 2016). Looking more closely into the facial expressions that have already been documented can help ascertain whether a discernible language is being used rather than individual basic expressions, however connections to the facial muscle responses including the ears has not been fully identified. This is the first study to claim this.

Looking at the importance of the context of which facial actions were made, including the ear actions, requires full detail of both parties and the environment around them.