I have a coloured pony gelding (10 year old) that is usually placid, kind and mannerly.... no problem in any way. He has lived happily and placidly with a mixed group of youngstock before, as well as mixed horses and ponies at livery. He is usually at the bottom of the pecking order, or certainly towards the bottom.
I have decided to proceed and get him long term companionship with 2 fillies. These fillies are yearlings, so quite a lot smaller and obviously less life experience than the gelding.
Having got the fillies accustomed to each other over weeks turned out together, I turned them out with the gelding.
I didn't anticipate any problems. The gelding has always been amenable and fair with other ponies he has been turned out. And have only ever observed subtle body language (ears back etc) - never seen him make contact with another pony.
However when he approached the fillies in the field, they ran! He followed. Initially he was just exuberant - tail up, neck arched, prancing with them... they ran as a bunch. Sometimes the fillies were in the lead, sometimes he led. No dominant behaviour, just high spirits as they explored the field boundaries.
But after about 10 minutes, there was a change in behaviour. He became more aggressive. Almost frustrated. Again no kicking, but ears back, trying to split up the two fillies by cantering between them, and then chasing after one of them alone... and if he could biting the top of their necks.
After about an hour, all ponies exhausted, and things had slowed down to a trot... but still the gelding moved the fillies around.
Not once did they touch noses, or interact. The fillies simply tried to keep out of his way.
I think that if they turned to face him, things would have wound down - but they didn't.
I removed the fillies for fear of injury if I left them.
Have I been naive trying to mix an adult with yearlings? If I try again, is the whole episode likely to repeat, or is this the worst of it over?
Any ideas on how to proceed?