Horse hair icicles on the fence

We were fascinated by these icicles that had formed around horse hairs at Campfield Marsh. Why only on the hairs but not on the barbed wire? We don't know whether they had formed on the wire but already melted. The metal of the wire is a good thermal conductor because of its delocalised electrons. It feels cold to the touch because it conducts thermal energy away from your hand. So maybe water should freeze more quickly on the wire. That might mean that ice would melt more quickly on metal than on an insulator. https://www.nuffieldfoundation.org/sites/default/files/files/Melting%20ice%20-%20merged%20PDF.pdf So perhaps that's the explanation - that there was ice on the fence but that it had melted.