Domestic horses send signals to humans when they face with an unsolvable task

Some domestic animals are thought to be skilled at social communication with humans due to the process of domestication. Horses, being in close relationship with humans, similar to dogs, might be skilled at communication with humans. Previous studies have indicated that they are sensitive to bodily signals and the attentional state of humans; however, there are few studies that investigate communication with humans and responses to the knowledge state of humans. Our first question was whether and how horses send signals to their potentially helpful but ignorant caretakers in a problem-solving situation where a food item was hidden in a bucket that was accessible only to the caretakers. We then examined whether horses alter their behaviours on the basis of the caretakers' knowledge of where the food was hidden. We found that horses communicated to their caretakers using visual and tactile signals. The signalling behaviour of the horses significantly increased in conditions where the caretakers had not seen the hiding of the food. These results suggest that horses alter their communicative behaviour towards humans in accordance with humans' knowledge state

伊豆諸島で繁殖するツバメの分散プロセス

学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 長谷川 壽一, 東京大学教授 岡ノ谷 一夫, 東京大学教授 渡辺 雄一郎, 東京大学講師 齋藤 慈子, 立教大学教授 上田 恵介University of Tokyo(東京大学

Feral horses’ (Equus ferus caballus) behavior toward dying and dead conspecifics

In the rapidly expanding field of comparative thanatology, reports from a wide range of taxa suggest that some aspects of a concept of death may be shared by many non-human species. In horses, there are only a few anecdotal reports on behaviors toward dead conspecifics, mostly concerning domestic individuals. Here, we describe the case of a 2-month-old, free-ranging male foal that died around 12 h after being found severely injured due to a presumed wolf attack, focusing on other individuals' reactions to the dying foal. We also placed camera traps near horse carcasses to investigate reactions by other horses. Kin and non-kin of both sexes showed unusual interest in the dying foal. However, horses appeared to avoid dead conspecifics. Recording individual reactions to dead and dying conspecifics in naturalistic settings will enhance our knowledge about death-related behaviors in horses, allowing comparisons with other species that have been more thoroughly studied, to understand the evolutionary basis of these behaviors

Aerial drone observations identified a multilevel society in feral horses

野生化したウマの重層社会をドローンからの観察により解明. 京都大学プレスリリース. 2021-01-18.The study of non-human multilevel societies can give us insights into how group-level relationships function and are maintained in a social system, but their mechanisms are still poorly understood. The aim of this study was to apply spatial association data obtained from drones to verify the presence of a multilevel structure in a feral horse society. We took aerial photos of individuals that appeared in pre-fixed areas and collected positional data. The threshold distance of the association was defined based on the distribution pattern of the inter-individual distance. The association rates of individuals showed bimodality, suggesting the presence of small social organizations or “units”. Inter-unit distances were significantly smaller than those in randomly replaced data, which showed that units associate to form a higher-level social organization or “herd”. Moreover, this herd had a structure where large mixed-sex units were more likely to occupy the center than small mixed-sex units and all-male-units, which were instead on the periphery. These three pieces of evidence regarding the existence of units, unit association, and stable positioning among units strongly indicated a multilevel structure in horse society. The present study contributes to understanding the functions and mechanisms of multilevel societies through comparisons with other social indices and models as well as cross-species comparisons in future studies

Social determinants of affiliation and cohesion in a population of feral horses

Investigating affiliative behaviors (e.g. proximity, grooming, cooperative behaviors) is essential to understand group cohesion and stability in animal societies, as they may foster, or be fostered by long-term social bonds and ultimately determine an individual’s lifetime reproductive success. Despite growing interest in affiliative behaviors across a wide range of mammalian taxa, little focus has been given to feral horse populations. In this study, we examined the influence of dyadic social factors (sex, rank difference, familiarity and genetic relatedness) on affiliative behaviors and group cohesion. We collected data on 16 feral horse groups in Northern Portugal who were subjected to both predation pressures and anthropogenic interference. A combination of all occurrence sampling methods and drone technology was used to record the horses’ social behavior and spatial data. Same-sex dyads showed a preference to remain in close proximity, however they did not groom as frequently as different-sex dyads. Similar rank individuals were observed in proximity more often than non-similar rank individuals, but only in newly formed groups. Familiar individuals spent more time in proximity and groomed more often than unfamiliar (new) dyads. However, affiliation between conspecifics was not predicted by genetic relatedness. These results suggest that social bonds and group cohesion are mostly sustained by familiar individuals in both stable and newly formed groups. While maintaining close proximity may function to sustain bonds between same-sex individuals, grooming may reinforce both intra-sexual and inter-sexual bonds. Examining the variation of affiliation patterns on horse populations may shed light on their behavioral plasticity and have crucial implications for the welfare and conservation of horse breeds

Population Characteristics of Feral Horses Impacted by Anthropogenic Factors and Their Management Implications

Feral horses form relatively stable harems over time that are characterized by long-lasting bonds among their members, a characteristic that makes them an exceptional case of a social system among terrestrial ungulates. Their social system has been described as uniform despite the wide differences in their environment and demography. Horse populations subjected to human interference often show higher levels of population instability that can ultimately compromise their reproductive success. In this article, we describe demographic and dynamic changes of a Portuguese population of Garranos in Serra d’Arga (SA), which is impacted by human and predation pressures, over six breeding seasons. Furthermore, we tested several hypotheses related to the impact of anthropogenic disturbance on the structure and dynamics of this population. Our results revealed that the SA population had relatively little human interference at the start of the project in 2016. This was supported by the natural composition of the herd (total number of individuals, 206), which consisted of several single- and multi-male harems (n = 17 and 7, respectively) and bachelor males (n = 9). However, from 2017 to 2021, SA’s Garrano population suffered a drastic decline. Approximately two-thirds of the individuals and all bachelor males disappeared, and 76% of adult female transfers occurred after the death or disappearance of the harem male. Predatory pressures and poor management of the population, which allowed illegal human interference, contributed to this population crisis. A low population growth rate, reduced birth and foal survival rates, in addition to a delayed primiparous age were observed in this population and exacerbated after its drastic decline; suggesting the viability and survival of this Garrano population were compromised. Investigating the population demographic changes and their causes and consequences can provide guidelines for managing populations and help fight the extinction of horse breeds

Lateral position preference in grazing feral horses

Behavioural lateralisation is an effective way for animals to manage daily tasks by specialising behaviour to either side of the body. Many types of lateralisation are linked to the function of each brain hemisphere. Lateralisation of monitoring behaviour in mother–infant relationships occurs in a wide range of mammals, where infants frequently use their left eye to monitor their mother. However, few studies have focused on this type of spatial relationships among adults in daily life, such as during foraging. The present study focused on monitoring adult feral horse behaviour using quantitative analysis of spatial relationships, using drone technology. We found that horses form a localised spatial relationship with their nearest neighbour. Specifically, the nearest neighbour was located to the left rear of a target individual significantly more frequently than to the right rear. Furthermore, the nearest neighbour was less frequently located behind a target individual. We propose that this relationship is caused by a left‐eye preference, because information via the left eye predominantly proceeds to the right hemisphere, which is dominant for social processing

Horses with sustained attention follow the pointing of a human who knows where food is hidden

International audienceWhen interacting with humans, domesticated species may respond to communicative gestures, such as pointing. However, it is currently unknown, except for in dogs, if species comprehend the communicative nature of such cues. Here, we investigated whether horses could follow the pointing of a human informant by evaluating the credibility of the information about the food-hiding place provided by the pointing of two informants. Using an object-choice task, we manipulated the attentional state of the two informants during food-hiding events and differentiated their knowledge about the location of the hidden food. Furthermore, we investigated the horses’ visual attention levels towards human behaviour to evaluate the relationship between their motivation and their performance of the task. The result showed that horses that sustained high attention levels could evaluate the credibility of the information and followed the pointing of an informant who knew where food was hidden (Z = − 2.281, P = 0.002, n = 36). This suggests that horses are highly sensitive to the attentional state and pointing gestures of humans, and that they perceive pointing as a communicative cue. This study also indicates that the motivation for the task should be investigated to determine the socio-cognitive abilities of animals

Spatial positioning of individuals in a group of feral horses: a case study using drone technology

Spatial positioning of individuals in animal groups has been studied from numerous perspectives. However, although many studies have focused on spatial position in flocks of birds and schools of fish, relatively few studies have been conducted in mammals with high accuracy. Because some mammal species form societies, we wondered how social relationships among mammals within a group influence each individual’s spatial position. To address this issue, we used drones to obtain accurate positioning of individuals in a feral horse group on the Serra D’ Arga mountain in Portugal. The results of our study revealed the following characteristics: (1) the male in between social and spatial relationships indicated that they are independent from each other. The present study is the first to reveal the characteristics of spatial positioning in a mammalian group using drone technology. The harem group was located in the periphery; (2) as in other species, individuals had areas of repulsion and attraction, and (3) nearest neighbors were located more toward the sides than to the back or front. We also measured the social relationships between individuals in terms of grooming frequency. Social network analyses of the correlation between social and spatial relationships indicated that they are independent from each other. The present study is the first to reveal the characteristics of spatial positioning in a mammalian group using drone technology