Magpies on back of Highland Cows

Magpies on back of Highland Cows

Observation - Magpies on back of Highland Cows - UK and Ireland. Description: Is this normal magpie behaviour? A group of them were perched on the back of a Highland cow in close to where I live. They appeared to be pecking things( parasites?) from the back of the animal. Never seen this before. Sorry about the photo quality, at

Is this normal magpie behaviour? A group of them were perched on the back of a Highland cow in close to where I live. They appeared to be pecking things( parasites?) from the back of the animal. Never seen this before.
Sorry about the photo quality, at the limit of my zoom!