A wagtail and its friend

This wagtail amused me when it flew up to and then walked about very close to this cow on the Minchinhampton Common today. Neither of them seemed in the least perturbed. Starlings often swoop about the cows there, sometimes landing on the backs of the cows, but I didn't see any of them today.  

I like the close relationships between birds and cows, as most often seen with Cattle Egrets. I loved watching huge numbers of Cattle Egrets in Sri Lanka following the cows around the paddy fields. I suppose that the birds eat insects such as flies, fleas and ticks which gather on and around the cattle.