I cannot tell from your pictures, but africans are pretty easy to sex by appearance and sounds. The males are larger, more upright posture with a longer single honk, and the females are smaller, flatter backs, petite face, and a more staccato shorter honk, usually lower pitched. Boys like to arch their necks high with tip of nose to air. Girls tend to stick neck out lower, and parallel to the ground.
And... the first picture does look like a gander to me.