Nice shots. I was expecting to see some smiling monkeys or something. My mom is thrilled to see that you went to the Audubon Zoo, us being from New Orleans and all. I haven't been there in a decade probably.
Good job! Orangutans make such fun subjects. They're either doing something funny or have great expressions on their faces. Unfortunately at my zoo you have to shoot through glass- makes it a pain in the butt to get any good shots.
It's funny you mention you mention your..um.. displeasure with your Sigma lens. I have the same one and can't stand it! I