Hint: If their attention seems to be focused on the calf, that is a good thing.
Approach them from upwind, and let them see and smell you before you get too close. Sometimes a nervous mama cow will settle down a little bit, once she knows that the person approaching is someone they are familiar with, as opposed to a stranger.
Try and keep the calf between you and the cow whenever possible. If you get between mama and baby, you risk either mama thinking you are trying to take baby away, or (this seems to only be a problem with heifers) they shy away, instead of sticking by their calf.
If they are bobbing their heads up and down, not good, pawing the ground while head bobbing, worse, an actual snort, and you are pushing your luck.
I am seriously looking into building a sort of cage that you hook to an ATV, where the front end opens up. You drive so the calf winds up 'inside' and close the front gate. You then have a barrier between you and mama, with the weight of the cage, and ATV to help protect you. I have a neighbor with a bad knee, and got one because if he tried to sidestep a cow quickly, it could lock up, and cause him to fall, which wouldn't be good. Anyway, he says he is very, very impressed with how well it actually works. It has mesh sides, so the cow can smell baby, but the openings are small enough so she can't get her head in an opening, and lift it up.
