Here's a test for you A-.
If you stick to watching it pee you will never walk up on a nanny thinking you just killed a billy.
With a lot of goat hunts you are the only hunter looking at the animals so it doesn't hurt at all to be patient and now for sure.
At the same time, if you are hoping to shoot a B&C billy you aren't going to need to wait for it to pee to know if it is a billy. You will already know!
I would think Nanny as the Horns look thin BUT the Horns also look close together at the base indicating Billie. This means I need to wait