8 yr. old now flicks dirt behind to cover up #2. Why?

Our females do it; it's very annoying in the yard as they disturb the grass. Dogs have scent pads on the pads of their feet which leave their scent when they kick up turf like that. It's the same as when they urinate a few drops every so often on a walk. They're leaving "pee-mail". They also like to check everyone else's "pee-mail" as they walk, and then cover up another dog's scent with their own.