Horses living in groups are better at following human indications than horses living in individual paddocks

Wild horses live in complex social groups and can move an average distance of 9-16 kilometres in a day, and cover areas up to 40 km2 in one summer. In contrast, domestic horses are kept in enclosures and groups varying in size and even in individual stalls or small paddocks.

Horses living in bigger fields or pastures are more active -- they are free to move according to their needs -- and, for example, to look for shade or shelter against wind and rain. When living in a group, horses can fulfil their social needs, interact in complex ways with many individuals, and have enough space to avoid unwanted interactions.

"It has been observed in earlier studies that horses with access to a pasture with other horses showed better learning performance and were less aggressive towards humans than horses kept in individual stables. Therefore, we wanted to explore whether horses' social and physical environment affect their responsiveness to human indications," says the lead author of the study, Doctoral Researcher Océane Liehrmann from the Department of Biology at the University of Turku, Finland.

The international research team from the University of Turku and the University of Helsinki in Finland, and the National Research Institute for Agriculture, Food and Environment INRAE in France, observed and analysed horses' response to human indications according to the horses' living environment. In addition, the researchers studied whether the horse reacted differently when the indications were given by the familiar owner or a stranger. The researchers recruited 57 privately owned leisure horses from the Turku region in Finland to perform the behavioural tests.

Horses living in groups and large paddocks followed human indications more closely

In the research situation, the human informant -- either the owner or the researcher -- was standing between two buckets, with a piece of carrot hidden in each of them. The horses were led by an assistant to stand in front of the human informant. The human informant would then move toward one of the buckets and gaze and point towards it to indicate that the horse should go to that bucket. The horse was then released and had the choice of going to the pointed bucket or the opposite one. If the horse followed the human's indication and approached the pointed bucket, the informant opened the lid and let the horse have the carrot. If the horse chose the opposite bucket, the informant caught the horse and it did not get a carrot. The experiment was repeated 10 times per horse and the researchers analysed how many times the horses chose to follow the human indication over the 10 trials.

"Interestingly, horses living in groups of at least three individuals chose the pointed bucket more often than the horses living alone or in dyads. Similarly, horses living in pastures or big fields for at least 8 months per year followed the human indication more often than the horses living in stalls or small paddocks," Liehrmann describes.

In the study, the horses living in big pastures also lived in larger groups, whereas most of the horses living in small paddocks were alone or with just one other horse. Therefore, it was difficult to conclude whether social deprivation or the lack of space and enrichment has the greater impact on the results.

"However, domestic horses living in larger groups may benefit from stronger cognitive stimulation. Indeed, having the choice of interacting with various individuals promotes complex social situations from which the horses can learn and improve their socio-cognitive skills. This may also explain why horses living in groups had better success in the task that involved communication with humans," Liehrmann notes.

Context can impact the significance of familiarity to the human

The researchers also found that the horses' success in the task did not depend on the familiarity of the person giving the indication. The success rate was similar whether the informant was the owner or a stranger. This is inconsistent with the findings from previous experiments based on the same population of horses. In the previous study, Liehrmann and her research group found that familiarity with the handler can affect the horse's behaviour in novel situations.

"Our hypothesis is that the context may play a role when investigating the effect of human familiarity in human-animal interactions. In a more stressful environment, animals may rely more on a familiar human than on a stranger, while in a positive context, where animals already feel safe and benefit from a food reward, the identity of the interacting human may matter less," says Liehrmann and continues:

"Overall, our study shows that the living conditions of the horses had an impact on their ability to follow human indications. The living and social environments of horses are a challenge and open to debate in the equestrian world. These results support the idea that offering an appropriate environment to horses by providing access to pasture and the ability to freely interact with their own kind could contribute to the development of their social behaviour and extend to interaction with humans."