Well, with such pictures you can't make a bad website, of course!
I'm absolutely no nature/animal photographer, but that close-up "portrait" of an owl (with those big yellow eyes) I find really fabulous.
Still, I would rather choose a dark background (like you use in the photo-galleries) than a busier background image/photo, because it's quieter for the eyes of visitors, but this is ofcourse my personal choice/opinion.
What I really would change, because I find the individual images less nicely presented, is the all white background in "single" view. Actually a dark color and (if possible) more transparent look, I think, will give a better view of your pictures. (normally you can change things like that in the CSS/stylesheet of a website, don't know about the possibilities with your website) All in all a very nice looking website with perfect photography!
Gerard