Annagain
Well-Known Member
First of all, domesticated horses that we manage aren't the best to study in terms of working out horse behaviour. So what they do and don't do isn't really helpful in terms of working out the original functions of some behaviour.
Feral horse groups have specific rolling spots. They all roll in these spots - possibly originally chosen for the type of surface. The surface will help with coat care, reduce parasite load and probably scratch itchy bits and help with coat shedding. However, as the spots get used, they turn into little hollows with coat grease, shed hair and scents.
Feral groups are family units, and by using the same rolling spot, they develop a distinctive signature scent that's a combination of the whole group. Horses recognise each other very much more than we do using scent - because a lot of their interactions happen in the dark and they don't vocalise much. When meeting new horses, they extend their noses forward and smell each other.
Some aspects of the behaviour may be related to dominance - with dominance, you always have to ask which specific resource is being contested? In the case of rolling spots, you would want to roll first if you wanted to make sure the rest of the group had your scent. You would roll later if you wanted to make sure your scent carried as much of the rest of the group's as possible. If you were younger and more defenceless, it would probably make sense to cover yourself with everybody else's smell.
In domesticated situations, we do not have stable groups. The horses have been removed, very young, from any family grouping, and are frequently moved at our whim from group to group. Each time, they have to try to fit in with a new group of unfamiliar horses (and none of the horses in the group know each other very well). In addition, we separate them once a day, so any attempts they make to form a cohesive group are constantly interrupted. We also get worried when they actually manage to form a stable group and show us that they don't like being separated, so we shuttle them around again. Or stick them on individual turnout. And then we rug them, so all the coat grease and loose hair build up on the inside of the rug, meaning they can't transfer it to a rolling spot, and any rolling spot will do since none of them have a "family group" smell. And the act of rolling doesn't satisfy, since they're doing it with a rug on, and the sandy soil isn't getting worked into the coat.
Taking all that into account, rolling in domesticated horses is probably driven by quite strong and slightly frustrated urges to form stable groups with horses they don't know or trust much, and similarly frustrated urges to care for their own coat and skin.
A final thing I've noticed is that with unrugged horses, rolling has a weatherproofing function - they roll in mud when it gets windy, because the mud has a "hairspray" effect by sticking all the coat hairs together, making them more windproof
My group (live out, group is fairly stable with few coming and going and several long term "friends", and mostly unrugged) do share a few favourite rolling spots, and when the big one rolls, the others will usually follow, either in the same spot or adjacent.
Thanks for that. Mine is in a very stable herd and though most are rugged there are a few retired ones who are hairy and muddy. It makes a lot of sense to me that he's instinctively covering himself in the 'family smell' as he definitely relies on others for protection. He's always hiding behind someone (whether equine or human) when things kick off and does prefer it when everybody's friends!