Protection from the elements: a comparative study of hair density, shelter use and heat loss in donkeys, horses and mules

It is widely believed that donkeys are less adapted to wet, temperate climates than horses, often requiring shelter in addition to natural protection and rugs. However, to date there has been no scientific study assessing the shelter needs of donkeys and current guidelines often consider all horses and donkeys as a homogenous group. Our project provides a comprehensive assessment of the requirements of donkeys for protection from the elements across the four seasons in the British Isles and directly compares these findings to those from horses and mules. Some preliminary results are presented below

Horses discriminate between facial expressions of conspecifics

In humans, facial expressions are rich sources of social information and have an important role in regulating social interactions. However, the extent to which this is true in non-human animals, and particularly in non-primates, remains largely unknown. Therefore we tested whether domestic horses (Equus caballus) could discriminate between facial expressions of their conspecifics captured in different contexts, and whether viewing these expressions elicited functionally relevant reactions. Horses were more likely to approach photographic stimuli displaying facial expressions associated with positive attention and relaxation, and to avoid stimuli displaying an expression associated with aggression. Moreover, differing patterns of heart rate changes were observed in response to viewing the positive anticipation and agonistic facial expressions. These results indicate that horses spontaneously discriminate between photographs of unknown conspecifics portraying different facial expressions, showing appropriate behavioural and physiological responses. Thus horses, an animal far-removed from the primate lineage, also have the ability to use facial expressions as a means of gaining social information and potentially regulating social interactions

Weathering the weather: effects of the environment on donkey, mule and horse welfare

It is widely believed that donkeys are less adapted to wet, temperate climates than horses. To date there has been no scientific study assessing the shelter needs of donkeys. Our research addressed this important welfare area through three studies conducted in Devon, UK: (1) a comparison of hair coat properties between horses, mules and donkeys over the four seasons, (2) a behavioural study of shelter use (man-made and natural), and (3) a study of heat loss using infrared thermography. In study 1 hair samples were taken from 42 animals, 18 donkeys, 16 horses and eight mules, in March, June, September and December. The weight, length and width of hair were measured as indicators of the hair coat insulation properties. The donkeys’ coats properties did not differ much across the seasons, unlike the horses’, indicating that donkeys do not grow a winter coat. The donkeys’ coats were significantly lighter, shorter and thinner than that of horses and mules in winter. In study 2 the shelter seeking behaviour of 75 donkeys and 65 horses was observed over a period of 18 months. Results showed that donkeys’ and horses’ behaviour was differentially affected by environmental factors. When it rained there was a 54% increase in the number of donkeys in shelters and only a 14% increase in horses seeking shelter. Most donkeys stayed inside when the temperature was below 10°C and they came outside as temperatures increased. Horses preferred to be outside in temperatures up to 20°C, above which they started to seek shelter. In study 3 we used a thermoimaging camera to take photos of donkeys and horses at different temperatures. In addition to the rate of overall heat loss, the amount of heat lost from specific body areas was assessed (ears, neck, torso, rear and legs). In concordance with the findings of study 1 we found that in cold temperatures donkeys lose more heat than mules and horses, and also that their heat loss is higher through their ears and their rear. These findings provide valuable scientific evidence that can inform future guidelines on the welfare and shelter needs of equines and support the idea that donkeys are less well adapted to temperate climates and may require additional protection from the elements (in the form of man-made shelters) when compared to many horses

Shelter seeking behaviour of donkeys and horses in a temperate climate

Domestic donkeys descended from wild asses, adapted to the semi-arid climates of Africa, whereas domestic horses originate from more temperate areas of Eurasia. Despite this difference in evolutionary history, modern domestic equids can be found throughout the world, in a wide range of conditions, many of which are very different from their natural environments. To explore the protection from the elements that different equid species may require in the temperate climate of the UK, the shelter seeking behaviour of 135 donkeys and 73 horses was assessed across a period of 16 months, providing a total of 13513 observations. The location of each animal (inside a constructed shelter, outside unprotected or using natural shelter) was recorded alongside measures of environmental conditions including temperature, wind speed, lux, precipitation and level of insect challenge. Statistical models revealed clear differences in the constructed-shelter-seeking behaviour of donkeys and horses. Donkeys sought shelter significantly more often at lower temperatures whereas horses tended to move inside when the temperature rose above 20°C. Donkeys were more affected by precipitation, with the majority of them moving indoors when it rained. Donkeys also showed a higher rate of shelter use when wind speed increased to moderate, while horses remained outside. Horses appeared to be more affected by insect challenge, moving inside as insect harassment outside increased. There were also significant differences in the use of natural shelter by the two species, with donkeys using natural shelter relatively more often to shelter from rain and wind and horses seeking natural shelter relatively more frequently when sunny. These results reflect donkeys’ and horses’ adaptation to different climates and suggest that the shelter requirements of these two equid species differ, with donkeys seeking additional protection from the elements in temperate climates

Domestic horses (Equus caballus) prefer to approach humans displaying a submissive body posture rather than a dominant body posture

Signals of dominance and submissiveness are central to conspecific communication in many species. For domestic animals, sensitivities to these signals in humans may also be beneficial. We presented domestic horses with a free choice between two unfamiliar humans, one adopting a submissive and the other a dominant body posture, with vocal and facial cues absent. Horses had previously been given food rewards by both human demonstrators, adopting neutral postures, to encourage approach behaviour. Across four counterbalanced test trials, horses showed a significant preference for approaching the submissive posture in both the first trial and across subsequent trials, and no individual subject showed an overall preference for dominant postures. There was no significant difference in latency to approach the two postures. This study provides novel evidence that domestic horses may spontaneously discriminate between, and attribute communicative significance to, human body postures of dominance; and further, that familiarity with the signaller is not a requirement for this response. These findings raise interesting questions about the plasticity of social signal perception across the species barrier

Domestic horses (Equus caballus) discriminate between negative and positive human nonverbal vocalisations

The ability to discriminate between emotion in vocal signals is highly adaptive in social species. It may also be adaptive for domestic species to distinguish such signals in humans. Here we present a playback study investigating whether horses spontaneously respond in a functionally relevant way towards positive and negative emotion in human nonverbal vocalisations. We presented horses with positively- and negatively-valenced human vocalisations (laughter and growling, respectively) in the absence of all other emotional cues. Horses were found to adopt a freeze posture for significantly longer immediately after hearing negative versus positive human vocalisations, suggesting that negative voices promote vigilance behaviours and may therefore be perceived as more threatening. In support of this interpretation, horses held their ears forwards for longer and performed fewer ear movements in response to negative voices, which further suggest increased vigilance. In addition, horses showed a right-ear/left-hemisphere bias when attending to positive compared with negative voices, suggesting that horses perceive laughter as more positive than growling. These findings raise interesting questions about the potential for universal discrimination of vocal affect and the role of lifetime learning versus other factors in interspecific communication

Cross modal perception of body size in domestic dogs (Canis familiaris)

While the perception of size-related acoustic variation in animal vocalisations is well documented, little attention has been given to how this information might be integrated with corresponding visual information. Using a cross-modal design, we tested the ability of domestic dogs to match growls resynthesised to be typical of either a large or a small dog to size- matched models. Subjects looked at the size-matched model significantly more often and for a significantly longer duration than at the incorrect model, showing that they have the ability to relate information about body size from the acoustic domain to the appropriate visual category. Our study suggests that the perceptual and cognitive mechanisms at the basis of size assessment in mammals have a multisensory nature, and calls for further investigations of the multimodal processing of size information across animal species

Domestic horses (Equus caballus) discriminate between negative and positive human nonverbal vocalisations

The ability to discriminate between emotion in vocal signals is highly adaptive in social species. It may also be adaptive for domestic species to distinguish such signals in humans. Here we present a playback study investigating whether horses spontaneously respond in a functionally relevant way towards positive and negative emotion in human nonverbal vocalisations. We presented horses with positively- and negatively-valenced human vocalisations (laughter and growling, respectively) in the absence of all other emotional cues. Horses were found to adopt a freeze posture for significantly longer immediately after hearing negative versus positive human vocalisations, suggesting that negative voices promote vigilance behaviours and may therefore be perceived as more threatening. In support of this interpretation, horses held their ears forwards for longer and performed fewer ear movements in response to negative voices, which further suggest increased vigilance. In addition, horses showed a right-ear/left-hemisphere bias when attending to positive compared with negative voices, suggesting that horses perceive laughter as more positive than growling. These findings raise interesting questions about the potential for universal discrimination of vocal affect and the role of lifetime learning versus other factors in interspecific communication

The role of cat eye narrowing movements in cat–human communication

Domestic animals are sensitive to human cues that facilitate inter-specific communication, including cues to emotional state. The eyes are important in signalling emotions, with the act of narrowing the eyes appearing to be associated with positive emotional communication in a range of species. This study examines the communicatory significance of a widely reported cat behaviour that involves eye narrowing, referred to as the slow blink sequence. Slow blink sequences typically involve a series of half-blinks followed by either a prolonged eye narrow or an eye closure. Our first experiment revealed that cat half-blinks and eye narrowing occurred more frequently in response to owners’ slow blink stimuli towards their cats (compared to no owner–cat interaction). In a second experiment, this time where an experimenter provided the slow blink stimulus, cats had a higher propensity to approach the experimenter after a slow blink interaction than when they had adopted a neutral expression. Collectively, our results suggest that slow blink sequences may function as a form of positive emotional communication between cats and humans

Consistency and flexibility in solving spatial tasks: different horses show different cognitive styles

Individual animals vary in their behaviour and reactions to novel situations. These differences may extend to differences in cognition among individuals. We tested twenty-six horses for their ability to detour around symmetric and asymmetric obstacles. All of the animals were able to get around the barrier to reach a food target, but varied in their approach. Some horses moved slowly but were more accurate in choosing the shortest way. Other horses acted quickly, consistently detoured in the same direction, and did not reliably choose the shortest way. The remaining horses shifted from a faster, directionally consistent response with the symmetric barrier, to a slower but more accurate response with the asymmetric barrier. The asymmetric barrier induced a reduction in heart rate variability, suggesting that this is a more demanding task. The different approaches used to solve the asymmetric task may reflect distinct cognitive styles in horses, which vary among individuals, and could be linked to different personality traits. Understanding equine behaviour and cognition can inform horse welfare and management